In addition to the energy-producing solar core, the interior has two distinct regions: a radiative zone and a convective zone. From the edge of the core outward, first through the radiative zone and then through the convective zone, the temperature decreases from 8 million to 7,000 K. It takes a few hundred thousand years for photons to escape from the dense core and reach the surface.
The Sun's "surface," known as the photosphere, is just the visible 500-km-thick layer from which most of the Sun's radiation and light finally escape, and it is the place where sunspots are found. Above the photosphere lies the chromosphere ("sphere of color") that may be seen briefly during total solar eclipses as a reddish rim, caused by hot hydrogen atoms, around the Sun. Temperature steadily increases with altitude up to 50,000 K, while density drops to 100,000 times less than in the photosphere.
He II (304 Å). Taken at 19:19 UT, 28 February 2000.
This image was taken by SOHO's EIT (Extreme-Ultraviolet Imaging Telescope) and is courtesy of the EIT Consortium. The wavelength is helium.
SOHO/MDI, SOHO/LASCO (ESA & NASA) SOHO is a project of international cooperation between ESA and NASA. |
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