Sunastronomy
Solar atmosphere » Chromosphere and corona
The ordinary solar spectrum is produced by the photosphere; during an eclipse the brilliant photosphere is blocked out by the Moon and three objects are visible: (1) a thin, pink ring around the edge of the Sun called the chromosphere, (2) a pearly, faint halo extending a great distance, known as the corona, and (3) pink clouds of gas called prominences suspended above the surface. When flash spectra (spectra of the atmosphere during an eclipse) were first obtained, astronomers found several surprising features. First, instead of absorption lines they saw emission lines (bright lines at certain wavelengths with nothing between them). This effect arises because the chromosphere is transparent between the spectrum lines, and only the dark sky is seen. Second, they discovered that the strongest lines were due to hydrogen, yet they still did not appreciate its high abundance. Finally, the next brightest lines had never been seen before; because they came from the Sun, the unknown source element came to be called helium. Later helium was found on Earth.
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Table of Contents
Media
- Figure 1: The internal rotation of the Sun as a function of depth and latitude, as derived from …[Credits : Big Bear Solar Observatory, California Institute of Technology]
- Figure 9: The gravitational force FG exerted by the Sun on the …
- Monthly satellite measurements of total solar irradiance since 1980 comparing NASA’s ACRIMSAT data …
- The trend shown in the longer reconstruction was inferred by Lean (2000) from modeling the changes …
- The eight planets of the solar system and Pluto, in a montage of images scaled to show the …[Credits : NASA/Lunar and Planetary Laboratory]
- Twelve solar X-ray images obtained by Yohkoh between 1991 and 1995. The solar coronal brightness …[Credits : G.L. Slater and G.A. Linford; S.L. Freeland; the Yohkoh Project]
- Venus crossing the face of the Sun, in a telescopic image recorded on a photographic plate on Dec. …[Credits : U.S. Naval Observatory Library]
- The Sun as imaged in extreme ultraviolet light by the Earth-orbiting Solar and Heliospheric …[Credits : NASA]
- The Sun, photographed by astronauts on NASA’s Skylab 4 mission (Nov. 16, 1973–Feb. 8, 1974). …[Credits : NASA]
- This time-lapse film shows the formation and dissolution of granules, updrafts of gas that form …[Credits : NASA]
- The solar corona is a veil of plasma surrounding the Sun. This film shows what the corona looks …[Credits : NASA]
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- Learn how the land, the air, the oceans, and the sun power the Earth’s weather.[Credits : Acquired from Vast Video]
- Learn what influences the Sun has on terrestrial weather, including the winds and oceans.[Credits : Acquired from Vast Video]
- Prominences are clouds of incandescent, ionized gas ejected from the Sun’s surface. They are also …[Credits : NASA]
- Total solar eclipse.[Credits : Encyclopædia Britannica, Inc.]
- Using their telescope, the brother and sister team of William and Caroline Herschel discovered the …[Credits : Acquired from Vast Video]
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