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Last updated on April 19, 2014 at 18:42 EDT

Sun Reference Libraries

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Chromosphere
2004-10-19 04:45:41

Chromosphere -- The chromosphere (literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere, roughly 10,000 kilometers deep. The chromosphere is more visually transparent than the photosphere. The most common solar feature within the chromosphere are spicules, long thin fingers of luminous gas which appear like the blades of a huge field of fiery grass...

Solar Wind
2004-10-19 04:45:41

Solar Wind -- Solar wind, a stream of particles (mostly high-energy protons ~ 500 Kev) that is continually ejected from the surface of the Sun. The composition of this plasma is identical to the Sun's corona, 73% hydrogen and 25% helium with the remainder as trace impurities, and is ionized. Near Earth, the velocity of the solar wind varies from 200km/s-889km/s. The average is 450 km/s....

Solar System
2012-10-22 06:09:41

The Solar System refers to the area in space that is dominated by our own Sun. It is comprised of the Sun and its associated astronomical objects that are held in its gravitational orbit. The Solar System was formed as a result of the collapse of a giant molecular cloud approximately 4.6 billion years ago. The mass of this system is located almost entirely in the Sun. Apart from the Sun, a high...

Solar Prominence
2004-10-19 04:45:41

Solar Prominence -- Solar prominences are large arch-shaped structures observable in the solar corona. These often have a twist and occasionally become unstable, ejecting plasma and magnetic flux out from the sun. The physics of solar prominence instability is believed to be governed by magnetic forces and magnetic helicity issues. It is thought that instability occurs when a magnetic flux...

Solar Maximum
2004-10-19 04:45:41

Solar Maximum -- The Sun, a roiling ball of plasma, occupies its place in space approximately 93 million miles from Earth. Though it seems simple to inhabitants of this planet -- the Sun shines, giving light and heat -- the processes occurring in the Sun are so complex that many scientists devote their careers to just one aspect of solar activity. Changes in the activity of the Sun...

Solar Flare
2004-10-19 04:45:41

Solar Flare -- A solar flare is a violent eruption that explodes from a star's photosphere with energies equivalent to tens of millions of hydrogen bombs. Solar flares from the Sun send out a streams of highly energetic solar wind that can present a radiation hazard to spacecraft outside of planetary magnetospheres and can disrupt radio signals on Earth. Solar flares were first observed...

Sunspot
2004-10-19 04:45:41

Sunspot -- A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings, and intense magnetic activity. Although they are blindingly bright, at temperatures of roughly 5000 Kelvin, the contrast with the surrounding material at some 6000 Kelvin leaves them clearly visible as dark spots. Interestingly, if they were isolated from the...

The Sun
2004-10-19 04:45:40

The Sun -- intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the solar system in their orbits. The sun is actually a star of about medium size; it appears larger than the other stars because of its relative nearness to the earth. The earth's distance from the sun varies from 91,377,000...

Mercury
2004-10-19 04:45:40

The Planet Mercury -- in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon as it completes each revolution about the sun, although the visible disk varies in size with respect to its distance from the earth. Because its greatest elongation is 28, it is seen...