The chromosphere (literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). The chromosphere is more visually transparent than the photosphere. The name comes from the fact that it has a reddish color, as the visual spectrum of the chromosphere is dominated by the deep red H-alpha spectral line of hydrogen. The coloration may be seen directly with the naked eye only during a total solar eclipse, where the chromosphere is briefly visible as a flash of color just as the visible edge of the photosphere disappears behind the Moon. The Sun is the star at the center of the Solar System. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... The photosphere of an astronomical object is the region at which the optical depth becomes one for a photon of wavelength equal to 5000 angstroms. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... In most modern usages of the word spectrum, there is a unifying theme of between extremes at either end. ... In physics and astronomy, H-alpha, also written Hα, is a particular emission line created by hydrogen. ... Photo taken during the 1999 eclipse. ... Apparent magnitude: up to -12. ...

Without special equipment the chromosphere cannot normally be seen due to its being washed out by the overwhelming brightness of the photosphere. It can be seen clearly through special narrow-band optical filters tuned to the H-alpha spectral line, and many observatories routinely observe the chromosphere using this technique, which displays filaments quite clearly. Filaments (and prominences, which are filaments viewed from the side) are the source of many coronal mass ejections and hence are important to prediction of space weather. A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... Aurora australis observed by Discovery, May 1991. ...

Photo taken by Luc Viatour during the French 1999 eclipse

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 growing upwards from the photosphere below. Spicules rise to the top of the chromosphere and then sink back down again over the course of about 10 minutes. Download high resolution version (945x940, 371 KB) oder phase photography: http://fr. ... Download high resolution version (945x940, 371 KB) oder phase photography: http://fr. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... Discovered in 1877 by Father Angelo Secchi of the Vatican Observatory in Rome, a spicule is a dynamic jet of about 500km diameter on the Sun. ... Subfamilies There are 7 subfamilies: Subfamily Arundinoideae Subfamily Bambusoideae Subfamily Centothecoideae Subfamily Chloridoideae Subfamily Panicoideae Subfamily Pooideae Subfamily Stipoideae The true grasses are monocotyledonous plants (Class Liliopsida) in the Family Poaceae, also known as Gramineae. ...

Another feature found in the chromosphere are fibrils, horizontal wisps of gas similar in extent to spicules but with about twice the duration.

Finally, solar prominences rise up through the chromosphere from the photosphere, sometimes reaching altitudes of 150,000 kilometers. These gigantic plumes of gas are the most spectacular of solar phenomena, aside from the less frequent solar flares. Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmosphere with its magnetic field. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ...

Above the chromosphere of some stars there is a so-called transition region, where the temperature increases rapidly to the hot corona, which forms the outermost part of the atmosphere. TRACE 19. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ...

See the flash spectrum of the solar chromosphere (Eclipse of March 7th, 1970).

The Sun v • d • e
Structure: Solar Core - Radiation Zone - Convection Zone
Atmosphere - Photosphere - Chromosphere - Transition region - Corona
Extended Structure: Termination Shock - Heliosphere - Heliopause - Heliosheath - Bow Shock
Solar Phenomena: Sunspots - Faculae - Granules - Supergranulation - Solar Wind - Spicules
Coronal loops - Solar Flares - Solar Prominences - Coronal Mass Ejections
Moreton Waves - Coronal Holes
Other: Solar System - Solar Variation - Solar Dynamo - Heliospheric Current Sheet - Solar Radiation - Solar Eclipse