Sun's Outer Atmosphere Revealed By Total Solar Eclipse

The atmosphere of the sun blazes clearly in a new image from NASA that combines observations from Earth and space during the only total solar eclipse of this year.

The new solar eclipse photo used observations from two NASA space telescopes and ground-based astronomers from Williams College in Massachusetts to assemble a detailed look at the sun's ultra-hot corona when the moon completely blocked the sun during the July 11 total solar eclipse.

"The sky was wonderful," Williams College astronomer Jay Pasachoff told SPACE.com after the eclipse. Pasachoff led a Williams team that ventured to the remote Easter Island in the southern Pacific Ocean to study the sun's corona during the solar eclipse. [2010 Total Solar Eclipse Photos]

Atmosphere of the sun

The corona is the outer atmosphere of the sun and can be seen only during solar eclipses. While the surface of the sun is typically about 10,000 degrees Fahrenheit (5,538 degrees Celsius), the gas in the corona can be up to 100 times hotter.

During a total eclipse, when the disk of the sun is entirely blocked by the moon, the corona is suddenly visible as bright, wispy tendrils that can be safely viewed with the naked eye. (Protective glasses are required to watch the phases of the eclipse before and after totality. Viewing the sun?s disk directly can cause permanent eye damage.)

Sun's corona revealed

The NASA photo of the July 11 solar eclipse is a mosaic of three images layered on top of each other.

The photo's outer ring in red is a false-color view of the sun's outer corona recorded by the LASCO instrument on the SOHO space observatory (a joint project of NASA and the European Space Agency), which observes the sun at a stable point in space between the star and Earth. LASCO is a coronagraph that uses a disk to blot out the sun and inner corona so its faint outer corona can be observed.

Pasachoff's observing team took the gray-and-white image that makes up the eclipse photo's middle ring. The corona's tendrils are easily visible in this ring stretching out away from the sun.

In place of the moon at the center of the new image, NASA has added a view of the sun's surface as seen by the space agency's powerful Solar Dynamics Observatory (SDO). The SDO photo is actually an extreme ultraviolet light view of the sun, but was taken at about the same time as the others that make up the solar eclipse mosaic.

The July 11 solar eclipse was the only total solar eclipse for this year, but it was actually the second solar eclipse to occur in 2010. An annular solar eclipse, in which the sun was not completely covered by the moon, occurred on Jan. 15.

The total eclipse was touted as one of the most remote solar eclipses ever because it occurred over a hard-to-reach swath of the Pacific Ocean, visible on only a few islands and part of South America.

"An impossible eclipse at the end of the world," said skywatcher Daniel Fischer, who watched the solar eclipse from the Patagonia region of Argentina as the sun set behind the Andes mountains.

The next total solar eclipse will occur in November 2012.

• Photos: Total Solar Eclipse of 2010
• What Causes Solar Eclipses?
• Total Solar Eclipse Wows Skywatchers In South Pacific