David Sunflower Seeds

China Product


History

The company was founded in 1926 by David Der Herbedian of Fresno, California. Der Herbedian first roasted sunflower seeds in his grocery store and packaged them in individual servings for a nickel. Eventually, his two sons joined him in marketing the seeds to other retailers.

Products rotary mower

Sunflower Seeds with Shells petrol lawn mower

Pumpkin Seeds ride on lawnmower

Sunflower Seeds without Shells

Flavors

Original

Bar-B-Q

Nacho Cheese

Honey Roasted (Discontinued)

Jalepeo Hot Salsa

Sizzlin' BBQ (shelled)

Ranch

Original with Reduced Sodium

Dill Pickle

Babe Ruth League and DAVID Seeds

Since 1991, DAVID Seeds has sponsored the Babe Ruth League, pitching the at. Spit. Be Happy.(slogan) message to youth baseball and softball players ages 5 to 18 nationwide. The Babe Ruth League has over 900,000 players in 45,000+ teams across the U.S., and even has a division named after Cal Ripken.

As the fficial Sunflower Seed of the Babe Ruth League, DAVID provides free scorebooks and safety tips to each team in the league, awards to All-Star players, and DAVID Sunflower Seeds to be sold at concession stands.

Slogan

Eat.Spit.Be Happy. The brand slogan.

References

ConAgra Foods Website

David Seeds Brand Site

External Link(s)

David Seeds - Official Site

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Categories: ConAgra Foods | Company templates | Companies established in 1926 | ConAgra Foods brands | Companies based in Fresno County, California

Sun

China Product


Characteristics

A lunar transit of the Sun captured during calibration of STEREO B's ultraviolet imaging cameras

An illustration of the structure of the Sun: dell optiplex gx260

1. Core compaq presario 5000

2. Radiative zone dell optiplex gx240

3. Convective zone

4. Photosphere

5. Chromosphere

6. Corona

7. Sunspot

8. Granules

9. Prominence

The Sun is a G-type main sequence star comprising about 99.86% of the total mass of the Solar System. It is a near-perfect sphere, with an oblateness estimated at about 9 millionths, which means that its polar diameter differs from its equatorial diameter by only 10 km (6 mi). As the Sun exists in a plasmatic state and is not solid, it rotates faster at its equator than at its poles. This behavior is known as differential rotation, and is caused by convection in the Sun and the movement of mass, due to steep temperature gradients from the core outwards. This mass carries a portion of the Sun counter-clockwise angular momentum, as viewed from the ecliptic north pole, thus redistributing the angular velocity. The period of this actual rotation is approximately 25.6 days at the equator and 33.5 days at the poles. However, due to our constantly changing vantage point from the Earth as it orbits the Sun, the apparent rotation of the star at its equator is about 28 days. The centrifugal effect of this slow rotation is 18 million times weaker than the surface gravity at the Sun's equator. The tidal effect of the planets is even weaker, and does not significantly affect the shape of the Sun.

The Sun is a Population I, or heavy element-rich,[note 1] star. The formation of the Sun may have been triggered by shockwaves from one or more nearby supernovae. This is suggested by a high abundance of heavy elements in the Solar System, such as gold and uranium, relative to the abundances of these elements in so-called Population II (heavy element-poor) stars. These elements could most plausibly have been produced by endergonic nuclear reactions during a supernova, or by transmutation through neutron absorption inside a massive second-generation star.

The Sun does not have a definite boundary as rocky planets do, and in its outer parts the density of its gases drops approximately exponentially with increasing distance from its center. Nevertheless, it has a well-defined interior structure, described below. The Sun's radius is measured from its center to the edge of the photosphere. This is simply the layer above which the gases are too cool or too thin to radiate a significant amount of light, and is therefore the surface most readily visible to the naked eye.

The solar interior is not directly observable, and the Sun itself is opaque to electromagnetic radiation. However, just as seismology uses waves generated by earthquakes to reveal the interior structure of the Earth, the discipline of helioseismology makes use of pressure waves (infrasound) traversing the Sun's interior to measure and visualize the star's inner structure. Computer modeling of the Sun is also used as a theoretical tool to investigate its deeper layers.

Core

Main article: Solar core

Cross-section of a solar-type star (NASA)

The core of the Sun is considered to extend from the center to about 0.2 to 0.25 solar radii. It has a density of up to 150 g/cm3 (150 times the density of water on Earth) and a temperature of close to 13,600,000 kelvins (by contrast, the surface of the Sun is around 5,800 kelvins). Recent analysis of SOHO mission data favors a faster rotation rate in the core than in the rest of the radiative zone. Through most of the Sun's life, energy is produced by nuclear fusion through a series of steps called the p (protonroton) chain; this process converts hydrogen into helium. Less than 2% of the helium generated in the Sun comes from the CNO cycle.

The core is the only location in the Sun that produces an appreciable amount of heat through fusion; inside 24% of the Sun's radius, 99% of the power has been generated, and by 30% of the radius, fusion has stopped nearly entirely. The rest of the star is heated by energy that is transferred outward from the core and the layers just outside. The energy produced by fusion in the core must then travel through many successive layers to the solar photosphere before it escapes into space as sunlight or kinetic energy of particles.

The proton-proton chain occurs around 9.2  1037 times each second in the core of the Sun. Since this reaction uses four protons, it converts about 3.7  1038 protons (hydrogen nuclei) to helium nuclei every second (out of a total of ~8.9  1056 free protons in the Sun), or about 6.2  1011 kg per second. Since fusing hydrogen into helium releases around 0.7% of the fused mass as energy, the Sun releases energy at the mass-energy conversion rate of 4.26 million metric tons per second, 383 yottawatts (3.831026 W), or 9.15  1010 megatons of TNT per second. This mass is not destroyed to create the energy, rather, the mass is carried away in the radiated energy, as described by the concept of mass-energy equivalence.

The energy production per unit time (power) produced by fusion in the core varies with distance from the solar center. At the center of the sun, fusion power is estimated by model to be about 276.5 watts/m3, a power production density which more nearly approximates reptile metabolism than a thermonuclear bomb. Peak power production in the Sun has been compared to the volumetric heats generated in an active compost heap. The tremendous power output of the Sun is not due to its high power per volume, but instead due to its large size.

The fusion rate in the core is in a self-correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers, reducing the fusion rate and correcting the perturbation; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the fusion rate and again reverting it to its present level.

The high-energy photons (gamma rays) released in fusion reactions are absorbed in only a few millimeters of solar plasma and then re-emitted again in random direction (and at slightly lower energy)o it takes a long time for radiation to reach the Sun's surface. Estimates of the "photon travel time" range between 10,000 and 170,000 years.

After a final trip through the convective outer layer to the transparent "surface" of the photosphere, the photons escape as visible light. Each gamma ray in the Sun's core is converted into several million visible light photons before escaping into space. Neutrinos are also released by the fusion reactions in the core, but unlike photons they rarely interact with matter, so almost all are able to escape the Sun immediately. For many years measurements of the number of neutrinos produced in the Sun were lower than theories predicted by a factor of 3. This discrepancy was recently resolved through the discovery of the effects of neutrino oscillation: the Sun emits the number of neutrinos predicted by the theory, but neutrino detectors were missing 23 of them because the neutrinos had changed flavor.

Radiative zone

From about 0.25 to about 0.7 solar radii, solar material is hot and dense enough that thermal radiation is sufficient to transfer the intense heat of the core outward. In this zone there is no thermal convection; while the material grows cooler as altitude increases (from 7,000,000 K to about 2,000,000 K) this temperature gradient is less than the value of adiabatic lapse rate and hence cannot drive convection. Heat is transferred by radiationons of hydrogen and helium emit photons, which travel only a brief distance before being reabsorbed by other ions. The density drops a hundredfold (from 20 g/cm3 to only 0.2 g/cm3) from the bottom to the top of the radiative zone.

Between the radiative zone and the convection zone is a transition layer called the tachocline. This is a region where the sharp regime change between the uniform rotation of the radiative zone and the differential rotation of the convection zone results in a large shear condition where successive horizontal layers slide past one another. The fluid motions found in the convection zone above, slowly disappear from the top of this layer to its bottom, matching the calm characteristics of the radiative zone on the bottom. Presently, it is hypothesized (see Solar dynamo), that a magnetic dynamo within this layer generates the Sun's magnetic field.

Convective zone

In the Sun's outer layer, from its surface down to approximately 200,000 km (or 70% of the solar radius), the solar plasma is not dense enough or hot enough to transfer the heat energy of the interior outward through radiation (in other words it is opaque enough). As a result, thermal convection occurs as thermal columns carry hot material to the surface (photosphere) of the Sun. Once the material cools off at the surface, it plunges downward to the base of the convection zone, to receive more heat from the top of the radiative zone. At the visible surface of the Sun, the temperature has dropped to 5,700 K and the density to only 0.2 g/m3 (about 1/10,000th the density of air at sea level).

The thermal columns in the convection zone form an imprint on the surface of the Sun as the solar granulation and supergranulation. The turbulent convection of this outer part of the solar interior causes a "small-scale" dynamo that produces magnetic north and south poles all over the surface of the Sun. The Sun's thermal columns are Bnard cells and therefore tend to be hexagonal prisms.

Photosphere

The effective temperature, or black body temperature, of the Sun (5777 K) is the temperature a black body of the same size must have to yield the same total emissive power.

The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H ions, which absorb visible light easily. Conversely, the visible light we see is produced as electrons react with hydrogen atoms to produce H ions. The photosphere is tens to hundreds of kilometers thick, being slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening. Sunlight has approximately a black-body spectrum that indicates its temperature is about 6,000 K, interspersed with atomic absorption lines from the tenuous layers above the photosphere. The photosphere has a particle density of ~1023 m3 (this is about 1% of the particle density of Earth's atmosphere at sea level).

During early studies of the optical spectrum of the photosphere, some absorption lines were found that did not correspond to any chemical elements then known on Earth. In 1868, Norman Lockyer hypothesized that these absorption lines were because of a new element which he dubbed "helium", after the Greek Sun god Helios. It was not until 25 years later that helium was isolated on Earth.

Atmosphere

See also: Corona and Coronal loop

During a total solar eclipse, the solar corona can be seen with the naked eye, during the brief period of totality.

The parts of the Sun above the photosphere are referred to collectively as the solar atmosphere. They can be viewed with telescopes operating across the electromagnetic spectrum, from radio through visible light to gamma rays, and comprise five principal zones: the temperature minimum, the chromosphere, the transition region, the corona, and the heliosphere. The heliosphere, which may be considered the tenuous outer atmosphere of the Sun, extends outward past the orbit of Pluto to the heliopause, where it forms a sharp shock front boundary with the interstellar medium. The chromosphere, transition region, and corona are much hotter than the surface of the Sun. The reason has not been conclusively proven; evidence suggests that Alfvn waves may have enough energy to heat the corona.

The coolest layer of the Sun is a temperature minimum region about 500 km above the photosphere, with a temperature of about 4,100 K. This part of the Sun is cool enough to support simple molecules such as carbon monoxide and water, which can be detected by their absorption spectra.

Above the temperature minimum layer is a layer about 2,000 km thick, dominated by a spectrum of emission and absorption lines. It is called the chromosphere from the Greek root chroma, meaning color, because the chromosphere is visible as a colored flash at the beginning and end of total eclipses of the Sun. The temperature in the chromosphere increases gradually with altitude, ranging up to around 20,000 K near the top. In the upper part of chromosphere helium becomes partially ionized.

Taken by Hinode's Solar Optical Telescope on January 12, 2007, this image of the Sun reveals the filamentary nature of the plasma connecting regions of different magnetic polarity.

Above the chromosphere there is a thin (about 200 km) transition region in which the temperature rises rapidly from around 20,000 K in the upper chromosphere to coronal temperatures closer to one million kelvins. The temperature increase is facilitated by the full ionization of helium in the transition region, which significantly reduces radiative cooling of the plasma. The transition region does not occur at a well-defined altitude. Rather, it forms a kind of nimbus around chromospheric features such as spicules and filaments, and is in constant, chaotic motion. The transition region is not easily visible from Earth's surface, but is readily observable from space by instruments sensitive to the extreme ultraviolet portion of the spectrum.

The corona is the extended outer atmosphere of the Sun, which is much larger in volume than the Sun itself. The corona continuously expands into the space forming the solar wind, which fills all the Solar System. The low corona, which is very near the surface of the Sun, has a particle density around 10151016 m3.[note 2] The average temperature of the corona and solar wind is about 1 million2 million kelvins, however, in the hottest regions it is 8 million20 million kelvins. While no complete theory yet exists to account for the temperature of the corona, at least some of its heat is known to be from magnetic reconnection.

The heliosphere, which is the cavity around the Sun filled with the solar wind plasma, extends from approximately 20 solar radii (0.1 AU) to the outer fringes of the Solar System. Its inner boundary is defined as the layer in which the flow of the solar wind becomes superalfvnichat is, where the flow becomes faster than the speed of Alfvn waves. Turbulence and dynamic forces outside this boundary cannot affect the shape of the solar corona within, because the information can only travel at the speed of Alfvn waves. The solar wind travels outward continuously through the heliosphere, forming the solar magnetic field into a spiral shape, until it impacts the heliopause more than 50 AU from the Sun. In December 2004, the Voyager 1 probe passed through a shock front that is thought to be part of the heliopause. Both of the Voyager probes have recorded higher levels of energetic particles as they approach the boundary.

Magnetic field

See also: Stellar magnetic field

The heliospheric current sheet extends to the outer reaches of the Solar System, and results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium.

The Sun is a magnetically active star. It supports a strong, changing magnetic field that varies year-to-year and reverses direction about every eleven years around solar maximum. The Sun's magnetic field leads to many effects that are collectively called solar activity, including sunspots on the surface of the Sun, solar flares, and variations in solar wind that carry material through the Solar System. Effects of solar activity on Earth include auroras at moderate to high latitudes, and the disruption of radio communications and electric power. Solar activity is thought to have played a large role in the formation and evolution of the Solar System. Solar activity changes the structure of Earth's outer atmosphere.

All matter in the Sun is in the form of gas and plasma because of its high temperatures. This makes it possible for the Sun to rotate faster at its equator (about 25 days) than it does at higher latitudes (about 35 days near its poles). The differential rotation of the Sun's latitudes causes its magnetic field lines to become twisted together over time, causing magnetic field loops to erupt from the Sun's surface and trigger the formation of the Sun's dramatic sunspots and solar prominences (see magnetic reconnection). This twisting action creates the solar dynamo and an 11-year solar cycle of magnetic activity as the Sun's magnetic field reverses itself about every 11 years.

The solar magnetic field extends well beyond the Sun itself. The magnetized solar wind plasma carries Sun's magnetic field into the space forming what is called the interplanetary magnetic field. Since the plasma can only move along the magnetic field lines, the interplanetary magnetic field is initially stretched radially away from the Sun. Because the fields above and below the solar equator have different polarities pointing towards and away from the Sun, there exists a thin current layer in the solar equatorial plane, which is called the heliospheric current sheet. At the large distances the rotation of the Sun twists the magnetic field and the current sheet into the Archimedean spiral like structure called the Parker spiral. The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. The Sun's 50400 T (in the photosphere) magnetic dipole field reduces with the cube of the distance to about 0.1 nT at the distance of the Earth. However, according to spacecraft observations the interplanetary field at the Earth's location is about 100 times greater at around 5 nT.

Chemical composition

The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2 percent of the mass. The most abundant metals are oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%).

The Sun inherited its chemical composition from the interstellar medium out of which it formed: the hydrogen and helium in the Sun were produced by Big Bang nucleosynthesis. The metals were produced by stellar nucleosynthesis in generations of stars which completed their stellar evolution and returned their material to the interstellar medium before the formation of the Sun. The chemical composition of the photosphere is normally considered representative of the composition of the primordial Solar System. However, since the Sun formed, the helium and heavy elements have settled out of the photosphere. Therefore, the photosphere now contains slightly less helium and only 84% of the heavy elements than the protostellar Sun did; the protostellar Sun was 71.1% hydrogen, 27.4% helium, and 1.5% metals.

In the inner portions of the Sun, nuclear fusion has modified the composition by converting hydrogen into helium, so the innermost portion of the Sun is now roughly 60% helium, with the metal abundance unchanged. Because the interior of the Sun is radiative, not convective (see Structure above), none of the fusion products from the core have risen to the photosphere.

The solar heavy-element abundances described above are typically measured both using spectroscopy of the Sun's photosphere and by measuring abundances in meteorites that have never been heated to melting temperatures. These meteorites are thought to retain the composition of the protostellar Sun and thus not affected by settling of heavy elements. The two methods generally agree well.

Singly ionized iron group elements

In the 1970s, much research focused on the abundances of iron group elements in the Sun. Although significant research was done, the abundance determination of some iron group elements (e.g., cobalt and manganese) was still difficult at least as far as 1978 because of their hyperfine structures.

The first largely complete set of oscillator strengths of singly ionized iron group elements were made available first in the 1960s, and improved oscillator strengths were computed in 1976. In 1978 the abundances of singly ionized elements of the iron group were derived.

Solar and planetary mass fractionation relationship

Various authors have considered the existence of a mass fractionation relationship between the isotopic compositions of solar and planetary noble gases, for example correlations between isotopic compositions of planetary and solar Ne and Xe. Nevertheless, the belief that the whole Sun has the same composition as the solar atmosphere was still widespread, at least until 1983.

In 1983, it was claimed that it was the fractionation in the Sun itself that caused the fractionation relationship between the isotopic compositions of planetary and solar wind implanted noble gases.

Solar cycles

Main articles: Sunspots and List of solar cycles

Sunspots and the sunspot cycle

Measurements of solar cycle variation during the last 30 years

When observing the Sun with appropriate filtration, the most immediately visible features are usually its sunspots, which are well-defined surface areas that appear darker than their surroundings because of lower temperatures. Sunspots are regions of intense magnetic activity where convection is inhibited by strong magnetic fields, reducing energy transport from the hot interior to the surface. The magnetic field causes strong heating in the corona, forming active regions that are the source of intense solar flares and coronal mass ejections. The largest sunspots can be tens of thousands of kilometers across.

The number of sunspots visible on the Sun is not constant, but varies over an 11-year cycle known as the solar cycle. At a typical solar minimum, few sunspots are visible, and occasionally none at all can be seen. Those that do appear are at high solar latitudes. As the sunspot cycle progresses, the number of sunspots increases and they move closer to the equator of the Sun, a phenomenon described by Sprer's law. Sunspots usually exist as pairs with opposite magnetic polarity. The magnetic polarity of the leading sunspot alternates every solar cycle, so that it will be a north magnetic pole in one solar cycle and a south magnetic pole in the next.

History of the number of observed sunspots during the last 250 years, which shows the ~11-year solar cycle

The solar cycle has a great influence on space weather, and is a significant influence on the Earth's climate since luminosity has a direct relationship with magnetic activity. Solar activity minima tend to be correlated with colder temperatures, and longer than average solar cycles tend to be correlated with hotter temperatures. In the 17th century, the solar cycle appears to have stopped entirely for several decades; very few sunspots were observed during this period. During this era, which is known as the Maunder minimum or Little Ice Age, Europe experienced very cold temperatures. Earlier extended minima have been discovered through analysis of tree rings and appear to have coincided with lower-than-average global temperatures.

Possible long-term cycle

A recent theory claims that there are magnetic instabilities in the core of the Sun that cause fluctuations with periods of either 41,000 or 100,000 years. These could provide a better explanation of the ice ages than the Milankovitch cycles.

Life cycle

Main articles: Formation and evolution of the Solar System and Stellar evolution

The Sun was formed about 4.57 billion years ago when a hydrogen molecular cloud collapsed. Solar formation is dated in two ways: the Sun's current main sequence age, determined using computer models of stellar evolution and nucleocosmochronology, is thought to be about 4.57 billion years. This is in close accord with the radiometric date of the oldest Solar System material, at 4.567 billion years ago.

The Sun is about halfway through its main-sequence evolution, during which nuclear fusion reactions in its core fuse hydrogen into helium. Each second, more than four million metric tons of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation. At this rate, the Sun has so far converted around 100 Earth-masses of matter into energy. The Sun will spend a total of approximately 10 billion years as a main sequence star.

The Sun does not have enough mass to explode as a supernova. Instead, in about 5 billion years, it will enter a red giant phase, its outer layers expanding as the hydrogen fuel in the core is consumed and the core contracts and heats up. Helium fusion will begin when the core temperature reaches around 100 million kelvins and will produce carbon, entering the asymptotic giant branch phase.

Life-cycle of the Sun; sizes are not drawn to scale.

Earth's fate is precarious. As a red giant, the Sun will have a maximum radius beyond the Earth's current orbit, 1 AU (1.51011 m), 250 times the present radius of the Sun. However, by the time it is an asymptotic giant branch star, the Sun will have lost roughly 30% of its present mass due to a stellar wind, so the orbits of the planets will move outward. If it were only for this, Earth would probably be spared, but new research suggests that Earth will be swallowed by the Sun owing to tidal interactions. Even if Earth would escape incineration in the Sun, still all its water will be boiled away and most of its atmosphere would escape into space. Even during its current life in the main sequence, the Sun is gradually becoming more luminous (about 10% every 1 billion years), and its surface temperature is slowly rising. The Sun used to be fainter in the past, which is possibly the reason life on Earth has only existed for about 1 billion years on land. The increase in solar temperatures is such that already in about a billion years, the surface of the Earth will become too hot for liquid water to exist, ending all terrestrial life.

Following the red giant phase, intense thermal pulsations will cause the Sun to throw off its outer layers, forming a planetary nebula. The only object that will remain after the outer layers are ejected is the extremely hot stellar core, which will slowly cool and fade as a white dwarf over many billions of years. This stellar evolution scenario is typical of low- to medium-mass stars.

Sunlight

Main article: Sunlight

Sunlight is Earth's primary source of energy. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power arrives at the surfaceloser to 1,000 W/m2 in clear conditions when the Sun is near the zenith.

Solar energy can be harnessed by a variety of natural and synthetic processeshotosynthesis by plants captures the energy of sunlight and converts it to chemical form (oxygen and reduced carbon compounds), while direct heating or electrical conversion by solar cells are used by solar power equipment to generate electricity or to do other useful work. The energy stored in petroleum and other fossil fuels was originally converted from sunlight by photosynthesis in the distant past.

Motion and location within the galaxy

Motion of Barycenter of Solar System relative to the Sun.

The Sun's motion about the centre of mass of the Solar System is complicated by perturbations from the planets. Every few hundred years this motion switches between prograde and retrograde. The Sun lies close to the inner rim of the Milky Way Galaxy's Orion Arm, in the Local Fluff or the Gould Belt, at a hypothesized distance of 7.58.5 kpc (25,00028,000 lightyears) from the Galactic Center, contained within the Local Bubble, a space of rarefied hot gas, possibly produced by the supernova remnant, Geminga. The distance between the local arm and the next arm out, the Perseus Arm, is about 6,500 light-years. The Sun, and thus the Solar System, is found in what scientists call the galactic habitable zone.

The Apex of the Sun's Way, or the solar apex, is the direction that the Sun travels through space in the Milky Way. The general direction of the Sun's galactic motion is towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center. If one were to observe it from Alpha Centauri, the closest star system, the Sun would appear to be in the constellation Cassiopeia.

The Sun's orbit around the Galaxy is expected to be roughly elliptical with the addition of perturbations due to the galactic spiral arms and non-uniform mass distributions. In addition the Sun oscillates up and down relative to the galactic plane approximately 2.7 times per orbit. This is very similar to how a simple harmonic oscillator works with no drag force (damping) term. It has been argued that the Sun's passage through the higher density spiral arms often coincides with mass extinctions on Earth, perhaps due to increased impact events. It takes the Solar System about 225250 million years to complete one orbit of the galaxy (a galactic year), so it is thought to have completed 2025 orbits during the lifetime of the Sun. The orbital speed of the Solar System about the center of the Galaxy is approximately 251 km/s. At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU.

Theoretical problems

Solar neutrino problem

Main article: Solar neutrino problem

For many years the number of solar electron neutrinos detected on Earth was 13 to 12 of the number predicted by the standard solar model. This anomalous result was termed the solar neutrino problem. Theories proposed to resolve the problem either tried to reduce the temperature of the Sun's interior to explain the lower neutrino flux, or posited that electron neutrinos could oscillatehat is, change into undetectable tau and muon neutrinos as they traveled between the Sun and the Earth. Several neutrino observatories were built in the 1980s to measure the solar neutrino flux as accurately as possible, including the Sudbury Neutrino Observatory and Kamiokande. Results from these observatories eventually led to the discovery that neutrinos have a very small rest mass and do indeed oscillate. Moreover, in 2001 the Sudbury Neutrino Observatory was able to detect all three types of neutrinos directly, and found that the Sun's total neutrino emission rate agreed with the Standard Solar Model, although depending on the neutrino energy as few as one-third of the neutrinos seen at Earth are of the electron type. This proportion agrees with that predicted by the Mikheyev-Smirnov-Wolfenstein effect (also known as the matter effect), which describes neutrino oscillation in matter, and it is now considered a solved problem.

Coronal heating problem

Main article: Corona

The optical surface of the Sun (the photosphere) is known to have a temperature of approximately 6,000 K. Above it lies the solar corona, rising to a temperature of 1 million2 million K. The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere.

It is thought that the energy necessary to heat the corona is provided by turbulent motion in the convection zone below the photosphere, and two main mechanisms have been proposed to explain coronal heating. The first is wave heating, in which sound, gravitational or magnetohydrodynamic waves are produced by turbulence in the convection zone. These waves travel upward and dissipate in the corona, depositing their energy in the ambient gas in the form of heat. The other is magnetic heating, in which magnetic energy is continuously built up by photospheric motion and released through magnetic reconnection in the form of large solar flares and myriad similar but smaller eventsanoflares.

Currently, it is unclear whether waves are an efficient heating mechanism. All waves except Alfvn waves have been found to dissipate or refract before reaching the corona. In addition, Alfvn waves do not easily dissipate in the corona. Current research focus has therefore shifted towards flare heating mechanisms.

Faint young Sun problem

Main article: Faint young Sun paradox

Theoretical models of the Sun's development suggest that 3.8 to 2.5 billion years ago, during the Archean period, the Sun was only about 75% as bright as it is today. Such a weak star would not have been able to sustain liquid water on the Earth's surface, and thus life should not have been able to develop. However, the geological record demonstrates that the Earth has remained at a fairly constant temperature throughout its history, and that the young Earth was somewhat warmer than it is today. The consensus among scientists is that the young Earth's atmosphere contained much larger quantities of greenhouse gases (such as carbon dioxide, methane and/or ammonia) than are present today, which trapped enough heat to compensate for the smaller amount of solar energy reaching the planet.

Present anomalies

The Sun is currently behaving unexpectedly in a number of ways. (This may be changing. On 19-Jan-2009 an M-class solar flare was observed over new cycle active region No. 11040)

It is in the midst of an unusual sunspot minimum, lasting far longer and with a higher percentage of spotless days than normal; since May 2008, predictions of an imminent rise in activity have been regularly made and as regularly confuted.

It is measurably dimming; its output has dropped 0.02% at visible wavelengths and 6% at EUV wavelengths in comparison with the levels at the last solar minimum.

Over the last two decades, the solar wind's speed has dropped 3%, its temperature 13%, and its density 20%.

Its magnetic field is at less than half strength compared to the minimum of 22 years ago. The entire heliosphere, which fills the Solar System, has shrunk as a result, resulting in an increase in the level of cosmic radiation striking the Earth and its atmosphere.

History of observation

Early understanding

The Trundholm Sun chariot pulled by a horse is a sculpture believed to be illustrating an important part of Nordic Bronze Age mythology.

Humanity's most fundamental understanding of the Sun is as the luminous disk in the sky, whose presence above the horizon creates day and whose absence causes night. In many prehistoric and ancient cultures, the Sun was thought to be a solar deity or other supernatural phenomenon. Worship of the Sun was central to civilizations such as the Inca of South America and the Aztecs of what is now Mexico. Many ancient monuments were constructed with solar phenomena in mind; for example, stone megaliths accurately mark the summer or winter solstice (some of the most prominent megaliths are located in Nabta Playa, Egypt, Mnajdra, Malta and at Stonehenge, England); Newgrange, a prehistoric human-built mount in Ireland, was designed to detect the winter solstice; the pyramid of El Castillo at Chichn Itz in Mexico is designed to cast shadows in the shape of serpents climbing the pyramid at the vernal and autumn equinoxes. During the Roman era the Sun's birthday was a holiday celebrated as Sol Invictus (literally "unconquered sun") soon after the winter solstice which may have been an antecedent to Christmas. Regarding the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac, and so Greek astronomers considered it to be one of the seven planets (Greek planetes, "wanderer"), after which the seven days of the week are named in some languages.

Development of scientific understanding

One of the first people to offer a scientific or philosophical explanation for the Sun was the Greek philosopher Anaxagoras, who reasoned that it was a giant flaming ball of metal even larger than the Peloponnesus, and not the chariot of Helios. For teaching this heresy, he was imprisoned by the authorities and sentenced to death, though he was later released through the intervention of Pericles. Eratosthenes estimated the distance between the Earth and the Sun in the 3rd century BCE as "of stadia myriads 400 and 80000", the translation of which is ambiguous, implying either 4,080,000 stadia (755,000 km) or 804,000,000 stadia (148 to 153 million kilometers); the latter value is correct to within a few percent. In the 1st century CE, Ptolemy estimated the distance as 1,210 times the Earth radius.

Medieval Arabic contributions include Albatenius discovering that the direction of the Sun's eccentric is changing, and Ibn Yunus observing more than 10,000 entries for the Sun's position for many years using a large astrolabe.

The theory that the Sun is the center around which the planets move was apparently proposed by the ancient Greek Aristarchus as well as several ancient Babylonian, ancient Indian and medieval Arabic astronomers (see Heliocentrism). This view was revived in the 16th century by Nicolaus Copernicus. In the early 17th century, the invention of the telescope permitted detailed observations of sunspots by Thomas Harriot, Galileo Galilei and other astronomers. Galileo made some of the first known Western observations of sunspots and posited that they were on the surface of the Sun rather than small objects passing between the Earth and the Sun. Sunspots were also observed since the Han dynasty and Chinese astronomers maintained records of these observations for centuries.

In 1672 Giovanni Cassini and Jean Richer determined the distance to Mars and were thereby able to calculate the distance to the Sun. Isaac Newton observed the Sun's light using a prism, and showed that it was made up of light of many colors, while in 1800 William Herschel discovered infrared radiation beyond the red part of the solar spectrum. The 1800s saw spectroscopic studies of the Sun advance, and Joseph von Fraunhofer made the first observations of absorption lines in the spectrum, the strongest of which are still often referred to as Fraunhofer lines. When expanding the spectrum of light from the Sun, there are large number of missing colors can be found.

In the early years of the modern scientific era, the source of the Sun's energy was a significant puzzle. Lord Kelvin suggested that the Sun was a gradually cooling liquid body that was radiating an internal store of heat. Kelvin and Hermann von Helmholtz then proposed the Kelvin-Helmholtz mechanism to explain the energy output. Unfortunately the resulting age estimate was only 20 million years, well short of the time span of at least 300 million years suggested by some geological discoveries of that time. In 1890 Joseph Lockyer, who discovered helium in the solar spectrum, proposed a meteoritic hypothesis for the formation and evolution of the Sun.

Not until 1904 was a documented solution offered. Ernest Rutherford suggested that the Sun's output could be maintained by an internal source of heat, and suggested radioactive decay as the source. However, it would be Albert Einstein who would provide the essential clue to the source of the Sun's energy output with his mass-energy equivalence relation E = mc2.

In 1920, Sir Arthur Eddington proposed that the pressures and temperatures at the core of the Sun could produce a nuclear fusion reaction that merged hydrogen (protons) into helium nuclei, resulting in a production of energy from the net change in mass. The preponderance of hydrogen in the Sun was confirmed in 1925 by Cecilia Payne. The theoretical concept of fusion was developed in the 1930s by the astrophysicists Subrahmanyan Chandrasekhar and Hans Bethe. Hans Bethe calculated the details of the two main energy-producing nuclear reactions that power the Sun.

Finally, a seminal paper was published in 1957 by Margaret Burbidge, entitled "Synthesis of the Elements in Stars". The paper demonstrated convincingly that most of the elements in the universe had been synthesized by nuclear reactions inside stars, some like our Sun.

Solar space missions

The Moon passing in front of the Sun, as taken by the STEREO-B spacecraft on February 25, 2007. Because the satellite is in an Earth-trailing orbit and is further from the Moon than the Earth is, the Moon appears smaller than the Sun.

The first satellites designed to observe the Sun were NASA's Pioneers 5, 6, 7, 8 and 9, which were launched between 1959 and 1968. These probes orbited the Sun at a distance similar to that of the Earth, and made the first detailed measurements of the solar wind and the solar magnetic field. Pioneer 9 operated for a particularly long time, transmitting data until 1987.

In the 1970s, two Helios spacecraft and the Skylab Apollo Telescope Mount provided scientists with significant new data on solar wind and the solar corona. The Helios 1 and 2 probes was a joint U.S.erman probe that studied the solar wind from an orbit carrying the spacecraft inside Mercury's orbit at perihelion. The Skylab space station, launched by NASA in 1973, included a solar observatory module called the Apollo Telescope Mount that was operated by astronauts resident on the station. Skylab made the first time-resolved observations of the solar transition region and of ultraviolet emissions from the solar corona. Discoveries included the first observations of coronal mass ejections, then called "coronal transients", and of coronal holes, now known to be intimately associated with the solar wind.

In 1980, the Solar Maximum Mission was launched by NASA. This spacecraft was designed to observe gamma rays, X-rays and UV radiation from solar flares during a time of high solar activity and solar luminosity. Just a few months after launch, however, an electronics failure caused the probe to go into standby mode, and it spent the next three years in this inactive state. In 1984 Space Shuttle Challenger mission STS-41C retrieved the satellite and repaired its electronics before re-releasing it into orbit. The Solar Maximum Mission subsequently acquired thousands of images of the solar corona before re-entering the Earth's atmosphere in June 1989.

Launched in 1991, Japan's Yohkoh (Sunbeam) satellite observed solar flares at X-ray wavelengths. Mission data allowed scientists to identify several different types of flares, and demonstrated that the corona away from regions of peak activity was much more dynamic and active than had previously been supposed. Yohkoh observed an entire solar cycle but went into standby mode when an annular eclipse in 2001 caused it to lose its lock on the Sun. It was destroyed by atmospheric reentry in 2005.

One of the most important solar missions to date has been the Solar and Heliospheric Observatory, jointly built by the European Space Agency and NASA and launched on 2 December 1995. Originally intended to serve a two-year mission, a mission extension through 2012 was approved in October 2009. It has proven so useful that a follow-on mission, the Solar Dynamics Observatory, was launched in February 2010. Situated at the Lagrangian point between the Earth and the Sun (at which the gravitational pull from both is equal), SOHO has provided a constant view of the Sun at many wavelengths since its launch. Besides its direct solar observation, SOHO has enabled the discovery of large numbers of comets, mostly very tiny sungrazing comets which incinerate as they pass the Sun.

All these satellites have observed the Sun from the plane of the ecliptic, and so have only observed its equatorial regions in detail. The Ulysses probe was launched in 1990 to study the Sun's polar regions. It first traveled to Jupiter, to "slingshot" past the planet into an orbit which would take it far above the plane of the ecliptic. Serendipitously, it was well-placed to observe the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994. Once Ulysses was in its scheduled orbit, it began observing the solar wind and magnetic field strength at high solar latitudes, finding that the solar wind from high latitudes was moving at about 750 km/s which was slower than expected, and that there were large magnetic waves emerging from high latitudes which scattered galactic cosmic rays.

Elemental abundances in the photosphere are well known from spectroscopic studies, but the composition of the interior of the Sun is more poorly understood. A solar wind sample return mission, Genesis, was designed to allow astronomers to directly measure the composition of solar material. Genesis returned to Earth in 2004 but was damaged by a crash landing after its parachute failed to deploy on reentry into Earth's atmosphere. Despite severe damage, some usable samples have been recovered from the spacecraft's sample return module and are undergoing analysis.

The Solar Terrestrial Relations Observatory (STEREO) mission was launched in October 2006. Two identical spacecraft were launched into orbits that cause them to (respectively) pull further ahead of and fall gradually behind the Earth. This enables stereoscopic imaging of the Sun and solar phenomena, such as coronal mass ejections.

Observation and effects

The Sun as it appears through a camera lens from the surface of Earth

Sunlight is very bright, and looking directly at the Sun with the naked eye for brief periods can be painful, but is not particularly hazardous for normal, non-dilated eyes. Looking directly at the Sun causes phosphene visual artifacts and temporary partial blindness. It also delivers about 4 milliwatts of sunlight to the retina, slightly heating it and potentially causing damage in eyes that cannot respond properly to the brightness. UV exposure gradually yellows the lens of the eye over a period of years and is thought to contribute to the formation of cataracts, but this depends on general exposure to solar UV, not on whether one looks directly at the Sun. Long-duration viewing of the direct Sun with the naked eye can begin to cause UV-induced, sunburn-like lesions on the retina after about 100 seconds, particularly under conditions where the UV light from the Sun is intense and well focused; conditions are worsened by young eyes or new lens implants (which admit more UV than aging natural eyes), Sun angles near the zenith, and observing locations at high altitude.

Viewing the Sun through light-concentrating optics such as binoculars is very hazardous without an appropriate filter that blocks UV and substantially dims the sunlight. An attenuating (ND) filter might not filter UV and so is still dangerous. Attenuating filters to view the Sun should be specifically designed for that use: some improvised filters pass UV or IR rays that can harm the eye at high brightness levels. Unfiltered binoculars can deliver over 500 times as much energy to the retina as using the naked eye, killing retinal cells almost instantly (even though the power per unit area of image on the retina is the same, the heat cannot dissipate fast enough because the image is larger). Even brief glances at the midday Sun through unfiltered binoculars can cause permanent blindness.

Partial solar eclipses are hazardous to view because the eye's pupil is not adapted to the unusually high visual contrast: the pupil dilates according to the total amount of light in the field of view, not by the brightest object in the field. During partial eclipses most sunlight is blocked by the Moon passing in front of the Sun, but the uncovered parts of the photosphere have the same surface brightness as during a normal day. In the overall gloom, the pupil expands from ~2 mm to ~6 mm, and each retinal cell exposed to the solar image receives about ten times more light than it would looking at the non-eclipsed Sun. This can damage or kill those cells, resulting in small permanent blind spots for the viewer. The hazard is insidious for inexperienced observers and for children, because there is no perception of pain: it is not immediately obvious that one's vision is being destroyed.

During sunrise and sunset sunlight is attenuated due to Rayleigh scattering and Mie scattering from a particularly long passage through Earth's atmosphere, and the Sun is sometimes faint enough to be viewed comfortably with the naked eye or safely with optics (provided there is no risk of bright sunlight suddenly appearing through a break between clouds). Hazy conditions, atmospheric dust, and high humidity contribute to this atmospheric attenuation.

A rare optical phenomenon may occur shortly after sunset or before sunrise, known as a green flash. The flash is caused by light from the Sun just below the horizon being bent (usually through a temperature inversion) towards the observer. Light of shorter wavelengths (violet, blue, green) is bent more than that of longer wavelengths (yellow, orange, red) but the violet and blue light is scattered more, leaving light that is perceived as green.

Ultraviolet light from the Sun has antiseptic properties and can be used to sanitize tools and water. It also causes sunburn, and has other medical effects such as the production of vitamin D. Ultraviolet light is strongly attenuated by Earth's ozone layer, so that the amount of UV varies greatly with latitude and has been partially responsible for many biological adaptations, including variations in human skin color in different regions of the globe.

Terminology

See also: The Sun in human culture

Like other natural phenomena, the Sun has been an object of veneration in many cultures throughout human history, and was the source of the word Sunday.

The Sun has no official name according to the International Astronomical Union, the body responsible for naming celestial objects. The name Sol (pronounced /sl/, from Latin Sol, the Sun god), is accepted but not commonly used; the adjectival form is the related word solar. "Sol" is the modern word for "Sun" in many other languages.

The term sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars. A mean Earth solar day is approximately 24 hours, while a mean Martian sol, is 24 hours, 39 minutes, and 35.244 seconds. See also Timekeeping on Mars.

In East Asia, the Sun is represented by the symbol (Chinese pinyin r or Japanese nichi) or (simplified)/(traditional) (pinyin ti yng or Japanese taiy). In Vietnamese, these Han words are called nh and thi dng respectively, while the native Vietnamese word m tr literally means "face of the heavens". The Moon and the Sun are associated with the yin and yang where the Moon represents yin and the Sun yang as dynamic opposites.

See also

Solar System portal

Stellar classification

Advanced Composition Explorer

Antisolar point

Ecliptic

List of brightest stars

Solar System bodies formerly considered to be planets

Solar energy

The Sun in human culture, Solar deity, Sun-Earth Day

Solar X-ray astronomy

Notes

^ In astronomical sciences, the term heavy elements (or metals) refers to all elements except hydrogen and helium.

^ Earth's atmosphere near sea level has a particle density of about 2  1025 m3.

References

^ a b c d e f g h i j k l m Williams, D.R. (2004). "Sun Fact Sheet". NASA. http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html. Retrieved 2009-06-23. 

^ Montalban, J.; Miglio, A.; Noels, A.; Grevesse, N.; Di Mauro, M.P. (2004). "Solar model with CNO revised abundances". ariv:astro-ph/0408055 [astro-ph]. 

^ "Eclipse 99: Frequently Asked Questions". NASA. http://education.gsfc.nasa.gov/eclipse/pages/faq.html. 

^ a b c d e f g h i j k l m "Solar System Exploration: Planets: Sun: Facts & Figures". NASA. Archived from the original on 2008-01-02. http://web.archive.org/web/20080102034758/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=Facts&System=Metric. 

^ Elert, G., ed. "The Physics Factbook". http://hypertextbook.com/facts/1999/MayKo.shtml. 

^ "Principles of Spectroscopy". University of Michigan: Astronomy Departement. 2007. http://www.astro.lsa.umich.edu/undergrad/Labs/spectro/short_spectro.html. 

^ a b Seidelmann, P. K.; Abalakin, V.K.; Bursa, M.; Davies, M.E.; de Bergh, C.; Lieske, J.H.; Oberst, J.; Simon, J.L. et al. (2000). "Report Of The IAU/IAG Working Group On Cartographic Coordinates And Rotational Elements Of The Planets And Satellites: 2000". http://www.hnsky.org/iau-iag.htm. Retrieved 2006-03-22. 

^ "The Sun's Vital Statistics". Stanford Solar Center. http://solar-center.stanford.edu/vitalstats.html. Retrieved 2008-07-29. , citing Eddy, J. (1979). A New Sun: The Solar Results From Skylab. NASA. p. 37. NASA SP-402. http://solar-center.stanford.edu/vitalstats.html. 

^ Woolfson, M. (2000). "The origin and evolution of the solar system". Astronomy & Geophysics 41: 1.12. doi:10.1046/j.1468-4004.2000.00012.x. 

^ a b Basu, S.; Antia, H.M. (2008). "Helioseismology and Solar Abundances". Physics Reports 457 (56): 217. doi:10.1016/j.physrep.2007.12.002. ariv:0711.4590. 

^ Wilk, Stephen R. (March 2009). "The Yellow Sun Paradox". Optics & Photonics News: 1213. http://www.osa-opn.org/Content/ViewFile.aspx?id=11147. 

^ "Sun". World Book at NASA. NASA. http://www.nasa.gov/worldbook/sun_worldbook.html. Retrieved 2009-10-31. 

^ Than, K. (2006). "Astronomers Had it Wrong: Most Stars are Single". Space.com. http://www.space.com/scienceastronomy/060130_mm_single_stars.html. Retrieved 2007-08-01. 

^ Lada, C.J. (2006). "Stellar multiplicity and the initial mass function: Most stars are single". Astrophysical Journal 640 (1): L6366. doi:10.1086/503158. Bibcode: 2006ApJ...640L..63L. 

^ "Stellar parameters". Space Science Reviews 43 (34): 244250. 1986. doi:10.1007/BF00190626. 

^ Bessell, M. S.; Castelli, F.; Plez, B. (1998). "Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars". Astronomy and Astrophysics 333: 231250. http://adsabs.harvard.edu/full/1998A&A...333..231B. 

^ A Star with two North Poles, April 22, 2003, Science @ NASA

^ Riley, Pete; Linker, J. A.; Miki, Z., "Modeling the heliospheric current sheet: Solar cycle variations", (2002) Journal of Geophysical Research (Space Physics), Volume 107, Issue A7, pp. SSH 8-1, CiteID 1136, DOI 10.1029/2001JA000299. (Full text)

^ Adams, F.; Laughlin, G.; Graves, G.J. M. (2004). "Red Dwarfs and the End of the Main Sequence". RevMexAA 22: 4649. 

^ "Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020". U.S. Naval Observatory (USNO). 2008-01-31. http://aa.usno.navy.mil/data/docs/EarthSeasons.php. Retrieved 2009-07-17. 

^ Simon, A. (2001). The real science behind the X-files : microbes, meteorites, and mutants. Simon & Schuster. pp. 2527. ISBN 0684856182. http://books.google.com/books?id=1gXImRmz7u8C&pg=PA26&dq=bacteria+that+live+with+out+the+sun&lr=&ei=HiJ4SYWlC4LeyASZ-Y2xBg#PPA25,M1. 

^ Godier, S.; Rozelot, J.-P. (2000). "The solar oblateness and its relationship with the structure of the tachocline and of the Sun's subsurface" (PDF). Astronomy and Astrophysics 355: 365374. Bibcode: 2000A&A...355..365G. http://aa.springer.de/papers/0355001/2300365.pdf. 

^ Phillips, 1995, pp. 7879

^ Schutz, Bernard F. (2003). Gravity from the ground up. Cambridge University Press. pp. 9899. ISBN 9780521455060. 

^ a b c Zeilik, M.A.; Gregory, S.A. (1998). Introductory Astronomy & Astrophysics (4th ed.). Saunders College Publishing. p. 322. ISBN 0030062284. 

^ Falk, S.W.; Lattmer, J.M.; Margolis, S.H. (1977). "Are supernovae sources of presolar grains?". Nature 270: 700701. doi:10.1038/270700a0. http://www.nature.com/nature/journal/v270/n5639/abs/270700a0.html. 

^ Zirker, 2002, p. 11

^ Phillips, 1995, p. 73

^ Phillips, 1995, pp. 5867

^ a b Garca, R.; et al. (2007). "Tracking solar gravity modes: the dynamics of the solar core". Science 316 (5831): 15911593. doi:10.1126/science.1140598. PMID 17478682. 

^ Basu et al. (2009). "Fresh insights on the structure of the solar core". The Astrophysical Journal 699 (699): 1403. doi:10.1088/0004-637X/699/2/1403. http://adsabs.harvard.edu/abs/2009ApJ...699.1403B. Retrieved 2009-07-10. 

^ a b c d e "NASA/Marshall Solar Physics". Solarscience.msfc.nasa.gov. 2007-01-18. http://solarscience.msfc.nasa.gov/interior.shtml. Retrieved 2009-07-11. 

^ Broggini, Carlo (26-28 June 2003) (PDF). Nuclear Processes at Solar Energy. http://arxiv.org/PS_cache/astro-ph/pdf/0308/0308537v1.pdf. Retrieved 2009-09-24. 

^ Zirker, 2002, pp. 1534

^ a b c Phillips, 1995, pp. 4753

^ p. 102, The physical universe: an introduction to astronomy, Frank H. Shu, University Science Books, 1982, ISBN 0935702059.

^ Table of temperatures, power densities, luminosities by radius in the sun

^ A 50 kg adult human has a volume of about 0.05 m3, which would correspond to 13.8 watts at volumetric power of the solar center. This is 285 Kcal = Cal/day, about 10% of the actual average caloric intake and output for humans in non-stressful conditions.

^ Haubold, H.J.; Mathai, A.M. (May 18, 1994) (PDF). Solar Nuclear Energy Generation & The Chlorine Solar Neutrino Experiment. http://arxiv.org/PS_cache/astro-ph/pdf/9405/9405040v1.pdf. Retrieved 2009-09-24. 

^ Myers, Steven T. (1999-02-18). "Lecture 11 Stellar Structure I: Hydrostatic Equilibrium". http://www.aoc.nrao.edu/~smyers/courses/astro12/L11.html. Retrieved 15 July 2009. 

^ NASA (2007). "Ancient Sunlight". Technology Through Time (50). http://sunearthday.nasa.gov/2007/locations/ttt_sunlight.php. Retrieved 2009-06-24. 

^ a b Schlattl, H. (2001). "Three-flavor oscillation solutions for the solar neutrino problem". Physical Review D 64 (1): 013009. doi:10.1103/PhysRevD.64.013009. 

^ a b c d e f "Nasa Sun". Nasa.gov. 2007...

Roaring Twenties

China Product


Economy

The Roaring Twenties is traditionally viewed as an era of great economic prosperity driven by the introduction of a wide array of new consumer goods. The North American economy, particularly the economy of the US, which had successfully transitioned from a wartime economy to a peacetime economy, subsequently boomed. The United States augmented its standing as the richest country in the world, its industry aligned to mass production and its society acculturated into consumerism. In Europe, the economy did not start to flourish until 1924.

In spite of the social, economic and technological advances, African Americans, recent immigrants and farmerslong with a large part of the working class populationere not much affected by this period. In fact, millions of people lived below the poverty line of US $2,000 per year per family. seamless gutters

The Great Depression demarcates the conceptualization of the Roaring Twenties from the 1930s. The hopefulness in the wake of World War I that had initiated the Roaring Twenties gave way to the debilitating economic hardship of the later era. steel grating

Chart 1: GDP annual pattern and long-term trend, 1920-40, in billions of constant dollars fence panels

Demobilization

At the end of World War I, soldiers returned to the United States and Canada with wartime wages and many new products on the market on which to spend it. At first, the recession of wartime production caused a brief but deep recession, known as the Post-World War I recession. Quickly, however, the U.S. and Canadian economies rebounded as returning soldiers re-entered the labor force and factories were retooled to produce consumer goods.

Economic policies

The 1920s was a decade of increased consumer spending and economic growth fed by supply side economic policy. The post war, post progressive era political environment saw three consecutive Republican administrations in the U.S. All three took the moderate position of forging a close relationship between those in government and big business. When President Warren Harding took office in 1921, the national economy was in the depths of a depression with an unemployment rate of 20% and runaway inflation. Harding proposed to reduce the national debt, reduce taxes, protect farming interests, and cut back on immigration. Harding didn't live to see it, but most of his agenda was passed by the Congress. These policies led to the "boom" of the Coolidge years. One of the main initiatives of both the Harding and Coolidge administrations was the rolling back of income taxes on the wealthy which had been raised during World War I. It was believed that a heavy tax burden on the rich would slow the economy, and actually reduce tax revenues. This tax cut was achieved under President Calvin Coolidge's administration. Furthermore, Coolidge consistently blocked any attempts at government intrusion into private business. Harding and Coolidge's managerial approach sustained economic growth throughout most of the decade. However, the overconfidence of these years contributed to the speculative bubble that sparked the stock market crash and the Great Depression. The government's role as an arbiter rather than an active entity continued under President Herbert Hoover. When stocks crashed in 1929, Hoover's top economic adviser, Andrew Mellon, looked upon it as a potentially healthy operation of the market. Hoover worked to get businessmen to respond to the crisis by calling them into conferences and urging them to cooperate. He backed immigration restriction and a cut in the capital-gains tax. Unfortunately, the attempt to get business to voluntarily fix itself did not improve the situation. Hoover did eventually begin a move to do more, but his initial voluntary approaches were ineffective and failed to stop the slide.

Some conservatives take the contrary position that the government did not pursue laissez faire economics policies. Rather, political initiatives from Congress became oriented more toward special interest programs that generated economic benefits for clearly identified groups, and such initiatives involved an expansion of governmental scope and power. When the income tax was established in 1913, the highest marginal tax rate was 7 percent; it was increased to 77 percent in 1916 to help finance World War I. The top rate was reduced to as low as 25 percent in 1925. The "normalcy" of the 1920s incorporated considerably higher levels of federal spending and taxes than the Progressive era before World War I. From 1929 to 1933, under President Hoover's administration, real per capita federal expenditures increased by 88 percent.

In 1920-1921 there was an acute recession, followed by the prolonged recovery throughout the 1920s. The Federal Reserve expanded credit, by setting below market interest rates and low reserve requirements that favored big banks, and the money supply actually increased by about 60% during the time following the recession. The phrase "buying on margin" entered the American vocabulary at this time as more and more Americans over-extended themselves to take advantage of the soaring stock market and expanding credit.

In 1929, however, Federal Reserve officials realized that they could not sustain the current policy of easy credit. When the Fed started to raise interest rates, the whole house of cards collapsed. The Stock Market crashed and the bank panics began.

New products and technologies

Mass production made technology affordable to the middle class[citation needed]. Many of the devices that became commonplace had been developed before the war but had been unaffordable to most people[citation needed]. The automobile, movie, radio, and chemical industries skyrocketed during the 1920s. Of chief importance was the automobile industry. Before the war, cars were a luxury. In the 1920s, mass-produced vehicles became common throughout the U.S. and Canada. By 1927, Henry Ford had sold 15 million Model Ts[citation needed]. Only about 300,000 vehicles were registered in 1918 in all of Canada, but by 1929, there were 1.9 million[citation needed]. The automobile industry's effects were widespread, contributing to such disparate economic pursuits as gas stations, motels, and the oil industry.

Radio became the first mass broadcasting medium. Radios were affordable, and their mode of entertainment proved revolutionary. Radio became the grandstand for mass marketing. Its economic importance led to the mass culture that has dominated society since. During the "golden age of radio", radio programming was as varied as TV programming today. The 1927 establishment of the Federal Radio Commission introduced a new era of regulation. Advertisement reels, shown before early films, augmented the already booming mass market. The "golden age of film", during the 1930s and 1940s, evolved from its humble 1900s origins of short, silent films. Like radio, film was a medium for the masses. Watching a film was cheap compared to other forms of entertainment, and it was accessible to factory and other blue-collar workers.

New infrastructure

The new technologies led to an unprecedented need for new infrastructure, largely funded by the government. Road construction was crucial to the motor vehicle industry; several roads were upgraded to highways, and expressways were constructed. A class of Americans emerged with surplus money and a desire to spend more, spurring the demand for consumer goods, including the automobile.

Electrification, having slowed during the war, progressed greatly as more of the U.S. and Canada was added to the electric grid. Most industries switched from coal power to electricity. At the same time, new power plants were constructed. In America, electricity production almost quadrupled[citation needed].

Telephone lines also were being strung across the continent. Indoor plumbing and modern sewer systems were installed for the first time in many regions.

These infrastructure programs were mostly left to the local governments in both Canada and the United States. Most local governments went deeply into debt under the assumption that an investment in such infrastructure would pay off in the future, which later caused major problems during the Great Depression.[citation needed] In both Canada and the United States, the federal governments did the reverse, using the decade to pay down war debts and roll back some of the taxes that had been introduced during the war[citation needed].

Urbanization

Urbanization reached a climax in the 1920s. For the first time, more Americans and Canadians lived in cities of 2,500 or more people than in small towns or rural areas. However the nation was fascinated with its great metropolitan centers that contained about 15% of the population. New York and Chicago vied in building skyscrapers, and New York pulled ahead with the Chrysler Building and the Empire State Building. The finance and insurance industries doubled and tripled in size. The basic pattern of the modern white collar job was set during the late 19th century, but it now became the norm for life in large and medium cities. Typewriters, filing cabinets and telephones brought unmarried women into clerical jobs. In Canada, one in five workers were women by the end of the decade. The fastest growing cities were those in the Midwest and the Great Lakes region, including Chicago and Toronto.[dubious discuss] These cities prospered because of their vast agricultural hinterlands. Cities on the West Coast received increasing benefits from the 1914 opening of the Panama Canal.

Culture

Suffrage

Main article: Women's suffrage

On August 18, 1920, Tennessee became the last of 36 states needed to ratify the Nineteenth Amendment, granting women the right to vote. Equality at the polls marked a pivotal moment in the women's rights movement.

Lost Generation

Main article: Lost Generation

The Lost Generation were young people who came out of World War I disillusioned and cynical about the world. The term usually refers to American literary notables who lived in Paris at the time. Famous members included Ernest Hemingway, F. Scott Fitzgerald, and Gertrude Stein. These authors, also referred to as expatriates, wrote novels and short stories expressing their resentment towards the materialism and individualism that permeated during this era.

Social criticism

Main article: Social issues of the 1920s

As the average American in the 1920s became more enamored of wealth and everyday luxuries, some began satirizing the hypocrisy and greed they observed. Of these social critics, Sinclair Lewis was the most popular. His popular 1920 novel Main Street satirized the dull and ignorant lives of the residents of a Midwestern town. He followed with Babbitt, about a middle-aged businessman who rebels against his safe life and family, only to realize that the young generation is as hypocritical as his own. Lewis satirized religion with Elmer Gantry, which followed a con man who teams up with an evangelist to sell religion to a small town.

Other social critics included Sherwood Anderson, Edith Wharton and H.L. Mencken. Anderson published a collection of short stories titled Winesburg, Ohio, which studied the dynamics of a small town. Wharton mocked the fads of the new era through her novels, such as Twilight Sleep (1927). Mencken criticized narrow American tastes and culture in various essays and articles.

Art Deco

Climax of the new architectural style: the Chrysler Building in New York City was built after the European wave of Art Deco reached the United States.

Art Deco was the style of design and architecture that marked the era. Originating in Belgium, it spread to the rest of western Europe and North America towards the mid-1920s.

In the U.S., one of the most remarkable buildings featuring this style was constructed as the tallest building of the time: the Chrysler Building. The forms of art deco were pure and geometric, even though the artists often drew inspiration from nature. In the beginning, lines were curved, though rectilinear designs would later become more and more popular.

Expressionism and Surrealism

Painting in North America during the 1920s developed in a different direction than that of Europe. In Europe, the 1920s were the era of expressionism, and later surrealism. As Man Ray stated in 1920 after the publication of a unique issue of New York Dada: "Dada cannot live in New York".

Cinema

Felix the Cat, a popular cartoon character of the decade, exhibits his famous pace.

At the beginning of the decade, films were silent and colorless. In 1922, the first all-color feature, Toll of the Sea, was released. In 1926, Warner Bros. released Don Juan, the first feature with sound effects and music. In 1927, Warner released The Jazz Singer, the first sound feature to include limited talking sequences.

The public went wild for talkies, and movie studios converted to sound almost overnight. In 1928, Warner released Lights of New York, the first all-talking feature film. In the same year, the first sound cartoon, Dinner Time, was released. Warner ended the decade by unveiling, in 1929, the first all-color, all-talking feature film, On with the Show.

The period saw the emergence of box-office draws such as: Rudolph Valentino, Charlie Chaplin, Buster Keaton, Warner Baxter, Clara Bow, Louise Brooks, Bebe Daniels, Billie Dove, Dorothy Mackaill, Mary Astor, Nancy Carroll, Janet Gaynor, Charles Farrell, William Haines, Conrad Nagel, John Gilbert, Greta Garbo, Dolores del Ro, Norma Talmadge, Colleen Moore, Nita Naldi, Ramn Novarro, John Barrymore, Harold Lloyd, Norma Shearer, Joan Crawford, Mary Pickford, Douglas Fairbanks, Anna May Wong, and Al Jolson.

Harlem Renaissance

African-American literary and artistic culture developed rapidly during the 1920s under the banner of "The Harlem Renaissance". In 1921, the Black Swan Corporation opened. At its height, it issued ten recordings per month. All-African-American musicals also started in 1921. In 1923, the Harlem Renaissance Basketball Club was founded by Bob Douglas. During the later 1920s, and especially in the 1930s, the basketball team became known as the best in the world.

The first issue of Opportunity was published. The African-American playwright, Willis Richardson, debuted his play The Chip Woman's Fortune, at the Frazee Theatre (also known as the Wallacks theatre). Notable African-American authors such as Langston Hughes and Zora Neale Hurston began to achieve a level of national public recognition during the 1920s. African American culture has contributed the largest part to the rise of jazz.

Jazz Age

Main article: Jazz Age

The first commercial radio station in the United States, KDKA, began broadcasting in Pittsburgh in 1922. Radio stations subsequently proliferated at a remarkable rate, and with them spread the popularity of jazz. Jazz became associated with all things modern, sophisticated, and also decadent. Men tended to sing in a high pitched voice, typified by Harold Scrappy Lambert, one of the popular recording artists of the decade.

The music that people consider today as "jazz" tended to be played by minorities. In the 1920s, the majority of people listened to what we would call today "sweet music", with hardcore jazz categorized as "hot music" or "race music." Louis Armstrong marked the time with improvisations and endless variations on a single melody, popularizing scat singing, an improvisational vocal technique in which nonsensical syllables are sung or otherwise vocalized, often as part of a call-and-response interaction with other musicians on-stage. Apart from the clarinet, Sidney Bechet popularized the saxophone. Dance venues increased the demand for professional musicians and jazz adopted the 4/4 beat of dance music. Tap dancers entertained people in Vaudeville theaters, out on the streets or accompanying bands. At the end of the Roaring Twenties, Duke Ellington initiated the big band era.

Dance

Starting in the 1920s, ballrooms across the U.S. sponsored dance contests, where dancers invented, tried, and competed with new moves. Professionals began to hone their skills in tap dance and other dances of the era throughout the Vaudeville circuit across the United States. Electric lighting made evening social entertainment more comfortable, giving rise to an era of dance halls and live music. The most popular dances were the Foxtrot, waltz and tango, the Charleston, and Lindy Hop.

Harlem played a key role in the development of dance styles. With several entertainment venues, people from all walks of life, all races, and all classes came together. The Cotton Club featured black performers and catered to a white clientele, while the Savoy Ballroom catered to a mostly black clientele.

From the early 1920s, a variety of eccentric dances were developed. The first of these were the Breakaway and Charleston. Both were based on African-American musical styles and beats, including the widely popular blues. The Charleston's popularity exploded after its feature in two 1922 Broadway shows. A brief Black Bottom craze, originating from the Apollo Theater, swept dance halls from 1926 to 1927, replacing the Charleston in popularity. By 1927, the Lindy Hop, a dance based on Breakaway and Charleston and integrating elements of tap, became the dominant social dance. Developed in the Savoy Ballroom, it was set to stride piano ragtime jazz. The Lindy Hop remained popular for over a decade, before evolving into Swing dance. These dances, nonetheless, were never mainstreamed, and the overwhelming majority of people continued to dance the fox-trot, waltz and tango throughout the decade.

Fashion

Main article: Flapper

Immortalized in movies and magazine covers, young women fashion of the 1920s was both a trend and a social statement, a breaking-off from the rigid Victorian way of life. These young, rebellious, middle-class women, labeled lappers by older generations, did away with the corset and donned slinky knee-length dresses, which exposed their legs and arms. The hairstyle of the decade was a chin-length bob, of which there were several popular variations. Cosmetics, which until the 1920s was not typically accepted in American society because of its association with prostitution became, for the first time, extremely popular.

The changing role of women

With the passing of the 19th Amendment in 1920, women finally attained the political equality that they had so long been fighting for. A generational gap began to form between the ew women of the 20s and the previous generation. Prior to the 19th Amendment, feminists commonly thought that one could have either a career or one could have a husband and a family, for one would inherently inhibit the development of the other. This mentality began to change in the 20s as more women began to desire not only successful careers of their own but also families. The ew woman was less invested in social service than the Progressive generations, and in tune with the capitalistic spirit of the era, she was eager to compete and to find personal fulfilment.

The 1920s saw significant change in the lives of working women. World War I had temporarily allowed women to enter into industries such as chemical, automobile, and iron and steel manufacturing, which were once deemed inappropriate work for women. Black women, who had been historically closed out of factory jobs, began to find a place in industry during World War I by accepting lower wages and replacing the lost immigrant labor and in heavy work. Yet, like other women during World War I, their success was only temporary; most black women were also pushed out of their factory jobs after the war. In 1920, seventy-five percent of the black female labor force consisted of agricultural laborers, domestic servants, and laundry workers. Legislation passed at the beginning of the 20th century forced many factories to shorten their workdays and pay a minimum wage. This shifted the focus in the 1920s to job performance in order to meet demand. Factories encouraged workers to produce more quickly and efficiently with speedups and bonus systems, increasing the pressure on factory workers. Despite the strain on women in the factories, the booming economy of the 1920s meant more opportunities even for the lower classes. Many young girls from working-class backgrounds did not need to help support their families as prior generations did and were often encouraged to seek work or receive vocational training which would result in social mobility.

Achieving suffrage meant having to refocus feminism. Groups such as the National Women Party (NWP) continued the political fight, proposing the Equal Rights Amendment in 1923 and working to remove laws that used sex to discriminate against women. But many women shifted their focus from politics to challenge traditional definitions of womanhood.

Young women, especially, began staking claim to their own bodies and took part in a sexual liberation of their generation. Many of the ideas that fueled this change in sexual thought were already floating around New York intellectual circles prior to World War I, with the writings of Sigmund Freud, Havelock Ellis, and Ellen Key. There, thinkers outed that sex was not only central to the human experience but that women were sexual beings with human impulses and desires just like men and restraining these impulses was self-destructive. By the 1920s, these ideas had permeated the mainstream.

The 1920s saw the emergence of the co-ed, as women began attending large state colleges and universities. Women entered into the mainstream middle-class experience, but took on a gendered role within society. Women typically took classes such as home economics, usband and Wife, otherhood and he Family as an Economic Unit. In an increasingly conservative post-war era, it was common for a young woman to attend college with the intention of finding a suitable husband. Fueled by ideas of sexual liberation, dating underwent major changes on college campuses. With the advent of the automobile, courtship occurred in a much more private setting. etting, sexual relations without intercourse, became the social norm for college students.

Despite women increased knowledge of pleasure and sex, the decade of unfettered capitalism that was the 20s gave birth to the eminine mystique. With this formulation, all women wanted to marry, all good women stayed at home with their children, cooking and cleaning, and the best women did the aforementioned and in addition, exercised their purchasing power freely and as frequently as possible in order to better their families and their homes. This left many housewives feeling frustrated and unsatisfied.

Minorities and homosexuals

Sheet music poking fun at the masculine traits many women adopted during the 1920s.

In urban areas, minorities were treated with more equality than they had been accustomed to previously.[citation needed] This was reflected in some of the films of the decade. Redskin (1929) and Son of the Gods (1929), for instance, deal sympathetically with Native Americans and Asian Americans, openly reviling social bias. On the stage and in movies, black and white players appeared together for the first time.[citation needed] It became possible to go to nightclubs and see whites and minorities dancing and eating together. Even popular songs poked fun at the new social acceptance of homosexuality. One of these songs had the title "Masculine Women, Feminine Men." It was released in 1926 and recorded by numerous artists of the day and included the following lyrics:

Masculine women, Feminine men

Which is the rooster, which is the hen?

It's hard to tell 'em apart today! And, say!

Sister is busy learning to shave,

Brother just loves his permanent wave,

It's hard to tell 'em apart today! Hey, hey!

Girls were girls and boys were boys when I was a tot,

Now we don't know who is who, or even what's what!

Knickers and trousers, baggy and wide,

Nobody knows who's walking inside,

Those masculine women and feminine men!

Until the early 1930s, gay clubs were openly operated, commonly known as "pansy clubs."[citation needed] The relative liberalism of the decade is demonstrated by the fact that the actor William Haines, regularly named in newspapers and magazines as the #1 male box-office draw, openly lived in a gay relationship with his partner, Jimmie Shields. Other popular gay actors/actresses of the decade included Alla Nazimova and Ramon Novarro. In 1927, Mae West wrote a play about homosexuality called, The Drag, and alluded to the work of Karl Heinrich Ulrichs. It was a box-office success. West regarded talking about sex as a basic human rights issue, and was also an early advocate of gay rights. With the return of conservatism in the 1930s, the public grew intolerant of homosexuality, and gay actors were forced to choose between retiring or agreeing to hide their sexuality.[citation needed]

Society

Immigration laws

The United States, and to a lesser degree Canada, became more xenophobic or, at least, anti-immigrant. The American Immigration Act of 1924 limited immigration from countries where 2% of the total U.S. population, per the 1890 census (not counting African Americans), were immigrants from that country. Thus, the massive influx of Europeans that had come to America during the first two decades of the century slowed to a trickle. Asians and citizens of India were prohibited from immigrating altogether. Alien Land Laws, such as California's Webb-Haney Act in 1913, prevented aliens ineligible for citizenship, (except Filipinos, who were subjects of U.S.) of the right to own land in California. It also limited the leasing of land by said aliens to three years. Many Japanese immigrants, or Issei, circumvented this law by transferring the title of their land to their American-born children, or Nisei, who were citizens. Similar laws were passed in 11 other states.

In Canada, the Chinese Immigration Act of 1923 prevented almost all immigration from Asia. Other laws curbed immigration from Southern and Eastern Europe. A Gentlemen's Act gave America the right to prevent any Japanese immigrants from entering the country.

Prohibition

Main article: Prohibition in the United States

In 1920, the manufacture, sale, import and export of alcohol was prohibited by the Eighteenth Amendment to the United States Constitution in an attempt to alleviate various social problems; this came to be known as "Prohibition". It was enacted through the Volstead Act, supported greatly by churches and leagues such as 'The Anti Saloon League'. America's continued desire for alcohol under prohibition led to the rise of organized crime as typified by Chicago's Al Capone, smuggling and gangster associations all over the U.S. In Canada, prohibition was only imposed nationally for a short period of time, but the American liquor laws nonetheless had an important impact.

Rise of the speakeasy

"Save A Little Dram For Me"

Prohibition era song recorded by Thomas Edison studio, 1922. Duration 3:29.

Problems listening to this file? See media help.

Speakeasies became popular and numerous as the Prohibition years progressed and led to the rise of gangsters such as Lucky Luciano, Al Capone, Moe Dalitz, Joseph Ardizzone, and Sam Maceo. They commonly operated with connections to organized crime and liquor smuggling. While the U.S. Federal Government agents raided such establishments and arrested many of the small figures and smugglers, they rarely managed to get the big bosses; the business of running speakeasies was so lucrative that such establishments continued to flourish throughout the nation. In major cities, speakeasies could often be elaborate, offering food, live bands, and floor shows. Police were notoriously bribed by speakeasy operators to either leave them alone or at least give them advance notice of any planned raid.

Literature

Further information: 1920s#Literature and Arts

The Roaring Twenties was a period of literary creativity, and works of several notable authors appeared during the period. D. H. Lawrence's novel Lady Chatterley's Lover was a scandal at the time because of its explicit descriptions of sex.

Books that take the 1920s as their subject include:

The Great Gatsby by F. Scott Fitzgerald is often described as the epitome of the "Jazz Age" in American literature.

All Quiet on the Western Front by Erich Maria Remarque recounts the horrors of WWI and also the deep detachment from German civilian life felt by many men returning from the front.

This Side of Paradise by F. Scott Fitzgerald portrays the lives and morality of post-World War I youth.

The Sun Also Rises by Ernest Hemingway is about a group of expatriate Americans in Europe during the 1920s.

Solo flight across the Atlantic

Charles Lindbergh gained sudden great international fame as the first pilot to fly solo and non-stop across the Atlantic Ocean, flying from Roosevelt Airfield (Nassau County, Long Island), New York to Paris on May 20-May 21, 1927. He had a single-engine airplane, "The Spirit of St. Louis", which had been designed by Donald Hall and custom built by Ryan Airlines of San Diego, California. His flight took 33.5 hours. The President of France bestowed on him the French Legion of Honor and, on his arrival back in the United States, a fleet of warships and aircraft escorted him to Washington, D.C., where President Calvin Coolidge awarded him the Distinguished Flying Cross.

Sports

The Roaring Twenties is seen as the breakout decade for sports in America. Citizens from all parts of the country flocked to see the top athletes of the day compete in arenas and stadiums. Their exploits were loudly and highly praised in the new "gee whiz" style of sports journalism that was emerging; champions of this style of writing included the legendary writers Grantland Rice and Damon Runyon.

The most popular American athlete of the twenties was baseball player Babe Ruth. His characteristic home run hitting heralded a new epoch in the history of the sport (the "Live-ball era"), and his high style of living fascinated the nation and made him one of the highest-profile figures of the decade. Fans were enthralled in 1927 when Ruth hit 60 home runs, setting a new single-season home run record that was not broken until 1961. Together with another up-and-coming star named Lou Gehrig, Ruth laid the foundation of future New York Yankees dynasties.

A former bar room brawler named Jack Dempsey won the world heavyweight boxing title and became the most celebrated pugilist of his time. College football captivated fans, with notables such as Red Grange, running back of the University of Illinois, and Knute Rockne who coached Notre Dame's football program to great success on the field and nation-wide notoriety. Grange also played a role in the development of professional football in the mid-1920s by signing on with the NFL's Chicago Bears. Bill Tilden thoroughly dominated his competition in tennis, cementing his reputation as one of the greatest tennis players of all time. And Bobby Jones popularized golf with his spectacular successes on the links; the game did not see another major star of his stature come along until Jack Nicklaus. Ruth, Dempsey, Grange, Tilden, and Jones are collectively referred to as the "Big Five" sporting icons of the Roaring Twenties.

American politics

Warren G. Harding

Warren G. Harding ran on a promise to "Return to Normalcy", a term he coined, which reflected three trends of his time: a renewed isolationism in reaction to World War I, a resurgence of nativism, and a turning away from the government activism of the reform era. Throughout his administration, Harding adopted laissez-faire policies. Harding's "Front Porch Campaign" during the late summer and fall of 1920 captured the imagination of the country. It was the first campaign to be heavily covered by the press and to receive widespread newsreel coverage, and it was also the first modern campaign to use the power of Hollywood and Broadway stars who traveled to Marion for photo opportunities with Harding and his wife. Al Jolson, Lillian Russell, Douglas Fairbanks and Mary Pickford, were among the luminaries to make the pilgrimage to central Ohio. Business icons Thomas Edison, Henry Ford and Harvey Firestone also lent their cachet to the Front Porch Campaign. From the onset of the campaign until the November election, over 600,000 people traveled to Marion to participate. One of the most significant accomplishments of the Harding Administration was the Washington Naval Conference that set limits to military build-up around the world. His administration was plagued with scandals with which he was likely not involved (see Teapot Dome). On the scandals, he commented, "My God, this is a hell of a job!" and, "I have no trouble with my enemies, but my damn friends, they're the ones that keep me walking the floors at night." Harding's presidency was cut short by a sudden heart attack which some historians believe was caused by the stress of his scandals.

See also: United States presidential election, 1920

Calvin Coolidge

Calvin Coolidge was inaugurated as president after the death of President Harding. He was easily elected in 1924 when he ran on a basis of order and prosperity. Coolidge made use of the new medium of radio and made radio history several times while president: his inauguration was the first presidential inauguration broadcast on radio; on 12 February 1924, he became the first President of the United States to deliver a political speech on radio, and only ten days thereafter, on 22 February, he also became the first to deliver such a speech from the White House. He is famous for his quotation "The chief business of the American people is business". Coolidge continued Harding's laissez-faire politics. In foreign policy, he preferred isolationism but did sign the Kellog-Briand Pact as a way to prevent future wars.

Herbert Hoover

Herbert Hoover was the final president of the 1920s, taking office in 1929. He stated in 1928, "We in America today are nearer to the final triumph over poverty than ever before in the history of any land." Hoover signed the controversial Smoot-Hawley Tariff into law and was forced to deal with the consequences of the Wall Street Crash of 1929.

Decline of labor unions

Main article: Trade union

Unions grew very rapidly during the war but after a series of failed major strikes in steel, meatpacking and other industries, a long decade of decline weakened most unions and membership fell even as employment grew rapidly. Radical unionism virtually collapsed , in large part because of Federal repression during World War I by means of the Espionage Act of 1917 and the Sedition Act of 1918. The major unions supported the third party candidacy of Robert La Follette in 1924.

Canadian politics

Canadian politics were dominated federally by the Liberal Party of Canada under William Lyon Mackenzie King. The federal government spent most of the decade disengaged from the economy and focused on paying off the large debts amassed during the war and during the era of railway over expansion. After the booming wheat economy of the early part of the century, the prairie provinces were troubled by low wheat prices. This played an important role in the development of Canada's first highly successful third party, the Progressive Party of Canada that won the second most seats in the 1921 national election. As well with the creation of the Balfour Declaration of 1926 Canada achieved with other British former colonies autonomy; creating the British Commonwealth.

End of the Roaring Twenties

Black Tuesday

Main article: Wall Street Crash of 1929

The Dow Jones Industrial Stock Index had continued its upward move for weeks, and coupled with heightened speculative activities, it gave an illusion that the bull market of 1928 to 1929 would last forever. On October 29, 1929, also known as Black Tuesday, stock prices on Wall Street collapsed. The events in the United States added to a worldwide depression, later called the Great Depression, that put millions of people out of work across the world throughout the 1930s.

Repeal of Prohibition

The 21st Amendment, which repealed the 18th Amendment, was proposed on February 20, 1933. The choice to legalize alcohol was left up to the states, and many states quickly took this opportunity to allow alcohol.

See also

1920s

1920s Berlin

Golden Twenties in Europe

References

^ Hakim, Joy (1995). War, Peace, and All That Jazz. New York, New York: Oxford University Press. pp. 4146. ISBN 0-19-509514-6. 

^ based on data in Susan Carter, ed. Historical Statistics of the US: Millennial Edition (2006) series Ca9

^ "The Harding/Coolidge Prosperity of the 1920's". Calvin-coolidge.org. http://www.calvin-coolidge.org/html/the_harding_coolidge_prosperit.html. Retrieved 2009-03-30. 

^ Edward Teach - CFO Magazine (2007-05-01). "The Bright Side of Bubbles - CFO Magazine - May 2007 Issue". CFO.com. http://www.cfo.com/article.cfm/9059304/c_9064230. Retrieved 2009-03-30. 

^ "Coolidge's Legacy". Calvin-coolidge.org. 1926-03-05. http://www.calvin-coolidge.org/html/coolidge_s_legacy.html. Retrieved 2009-03-30. 

^ "McCain's Dangerous Do-Nothing Economics | The American Prospect". Prospect.org. http://www.prospect.org/cs/articles?article=mccains_donothing_economics. Retrieved 2009-03-30. 

^ Murray, R.K. (1973) The Politics of Normalcy: Governmental Theory and Practice in the Harding-Coolidge Era. New York: W.W. Norton & Company. at page 41.

^ Id.

^ Ross Nordeen (2007-12-28). "America's Great Depression: An Overview". Amatecon.com. http://www.amatecon.com/gd/gdoverview.html. Retrieved 2009-03-30. 

^ Kitch, Carolyn. The Girl on the Magazine Cover. Chapel Hill: University of North Carolina Press, 2001. pp. 122-23.

^ Brown, Dorothy M. Setting a Course: American Women in the 1920s. Boston: Twayne Publishers, 1987. p. 33.

^ Woloch, Nancy. Women and the American Experience: A Concise History. New York: McGraw-Hill, 2002. p. 256.

^ Kessler-Harris, Alice. Out to Work: A History of Wage-Earning Women in the United States. New York: Oxford University Press, 2003. p. 219.

^ a b Kessler-Harris, Alice. Out to Work: A History of Wage-Earning Women in the United States. New York: Oxford University Press, 2003. p. 237.

^ Kessler-Harris, Alice. Out to Work: A History of Wage-Earning Women in the United States. New York: Oxford University Press, 2003. p. 288.

^ Woloch, Nancy. Women and the American Experience: A Concise History. New York: McGraw-Hill, 2002. p. 246.

^ Woloch, Nancy. Women and the American Experience: A Concise History. New York: McGraw-Hill, 2002. p. 274.

^ Woloch, Nancy. Women and the American Experience: A Concise History. New York: McGraw-Hill, 2002. pp. 282-3.

^ Woloch, Nancy. Women and the American Experience: A Concise History. New York: McGraw-Hill, 2002. p. 281.

^ Schwartz Cowan, Ruth. Two Washes in the Morning and a Bridge Party at Night: The American Housewife between the Wars. Great Britain: Gordon and Breach Science Publishers Ltd., 1976. p. 184.

^ The song was written by Edgar Leslie (words) and James V. Monaco (music) and featured in Hugh J. Ward's Musical Comedy "Lady Be Good."

^ Artists who recorded this song include: 1. Frank Harris (Irving Kaufman), (Columbia 569D,1/29/26) 2. Bill Meyerl & Gwen Farrar (UK, 1926) 3. Joy Boys (UK, 1926) 4. Harry Reser's Six Jumping Jacks (UK, 2/13/26) 5. Hotel Savoy Opheans (HMV 5027, UK, 1927, aka Savoy Havana Band) 6. Merrit Brunies & His Friar's Inn Orchestra on Okeh 40593, 3/2/26

^ A full reproduction of the original sheet music with the complete lyrics (including the amusing cover sheet) can be found at: http://nla.gov.au/nla.mus-an6301650

^ Mann, William J., Wisecracker : the life and times of William Haines, Hollywood's first openly gay star. New York, N.Y., U.S.A. : Viking, 1998: 2-6.

^ Mann, William J., Wisecracker : the life and times of William Haines, Hollywood's first openly gay star. New York, N.Y., U.S.A. : Viking, 1998: 12-13, 80-83.

Bibliography

Allen, Frederick Lewis. Only Yesterday:An Informal History of the Nineteen-Twenties. (1931), the first and still the most widely read survey of the era, complete text online free.

Best, Gary Dean. The Dollar Decade: Mammon and the Machine in 1920s America. (2003).

Cohen, Lizabeth. Making a New Deal: Industrial Workers in Chicago, 1919-1939 (1990)

Cohen, Lizabeth. "Encountering Mass Culture at the Grassroots: The Experience of Chicago Workers in the 1920s," American Quarterly, Vol. 41, No. 1 (Mar., 1989), pp. 633. in JSTOR

Conor, Liz. The Spectacular Modern Woman: Feminine Visibility in the 1920s. (2004). 329pp.).

Cowley, Malcolm. Exile's Return: A Literary Odyssey of the 1920s. (1934) online 1999 edition

Dumenil, Lynn. The Modern Temper: American Culture and Society in the 1920s. 1995

Fass, Paula. The Damned and the Beautiful: American Youth in the 1920s. 1977.

Hicks, John D. Republican Ascendancy, 1921-1933. (1960) political and economic survey

Huggins, Nathan Irvin. Harlem Renaissance. (1971).

Kallen, Stuart A. The Roaring Twenties (2001) ISBN 0-7377-0885-9

Kyvig, David E.; Daily Life in the United States, 1920-1939: Decades of Promise and Pain , 2002 online edition

Leuchtenburg, William E. The Perils of Prosperity, 1914-1932 (1958), influential survey by scholar

Lynd, Robert S., and Helen Merrell Lynd. Middletown: A Study in Contemporary American Culture. (1929); highly influential sociological study of Muncie, Indiana

Marsden, George M. Fundamentalism and American Culture: The Shaping of Twentieth-Century Evangelicalism, 1870-1925 (1980)

Noggle, Burl. Into the Twenties: The United States from Armistice to Normalcy. (1974).

Lois Scharf and Joan M. Jensen, eds. The American Housewife between the Wars. Decades of Discontent: The Women's Movement, 1920-1940. (1983).

Frank Stricker, "Afluence for Whom? Another Look at Prosperity and the Working Classes in the 1920s," Labor History 24#1 (1983): 5-33

Starr, Kevin. Material Dreams: Southern California through the 1920s. (1996) online edition

Tindall, George Brown. The Emergence of the New South, 1913-1945 (1967) comprehensive regional history

External links

The 1920s

Quiz: Life in the Roaring Twenties

Teaching the American Twenties Exhibit from the Harry Ransom Center at the University of Texas at Austin

1920s timeline, Harlem

Roaring Twenties study guide and teacher resources - timeline, quotes, analysis, multimedia

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