Sun's Outer Atmosphere Revealed By Total Solar Eclipse

Theatmosphere of the sun blazes clearly in a new image from NASA thatcombinesobservations from Earth and space during the only total solar eclipseof thisyear.

Thenew solar eclipse photo used observations from twoNASA space telescopesand ground-based astronomers from Williams College in Massachusetts toassemblea detailed look at the sun's ultra-hot corona when the moon completelyblockedthe sun during the July 11 totalsolar eclipse.

"Thesky was wonderful," Williams College astronomer Jay Pasachoff toldSPACE.com after the eclipse. Pasachoff led a Williams team thatventured to theremote Easter Island in the southern Pacific Ocean to study the sun'scoronaduring the solar eclipse. [2010Total SolarEclipse Photos]

Atmosphereof the sun

Thecorona is the outer atmosphere of the sun and can be seen only during solareclipses.While the surfaceof the sun is typically about 10,000 degrees Fahrenheit (5,538 degreesCelsius), the gas in the corona can be up to 100 times hotter.

Duringa total eclipse, when the disk of the sun is entirely blocked by themoon, thecorona is suddenly visible as bright, wispy tendrils that can be safelyviewedwith the naked eye. (Protective glasses are required to watch thephases of theeclipse before and after totality. Viewing the sun?s disk directly cancausepermanent eye damage.)

Sun'scorona revealed

TheNASA photo of the July 11 solar eclipse is a mosaic of three imageslayered ontop of each other.

Thephoto's outer ring in red is a false-color view of the sun's outercoronarecorded by the LASCO instrument on the SOHO space observatory (a jointprojectof NASA and the European Space Agency), which observes the sun at astablepoint in space between the star and Earth. LASCO is a coronagraph thatuses adisk to blot out the sun and inner corona so its faint outer corona canbeobserved.

Pasachoff'sobserving team took the gray-and-white image that makes up the eclipsephoto'smiddle ring. The corona's tendrils are easily visible in this ringstretchingout away from the sun.

Inplace of the moon at the center of the new image, NASA has added a viewof thesun's surface as seen by the space agency's powerful Solar DynamicsObservatory(SDO). The SDO photo is actually an extreme ultraviolet light view ofthe sun,but was taken at about the same time as the others that make up thesolareclipse mosaic.

TheJuly 11 solar eclipse was the only total solar eclipse for this year,but itwas actually the second solar eclipse to occur in 2010. An annularsolareclipse, in which the sun was not completely covered by the moon,occurred onJan. 15.

Thetotal eclipse was touted as one of the most remote solar eclipses everbecauseit occurred over a hard-to-reach swath of the Pacific Ocean, visible ononly afew islands and part of South America.

"Animpossible eclipse at the end of the world," said skywatcher DanielFischer, who watched the solar eclipse from the Patagonia region ofArgentinaas the sun set behind the Andes mountains.

Thenext total solar eclipse will occur in November 2012.

• Photos:TotalSolar Eclipse of 2010
• WhatCausesSolar Eclipses?
• TotalSolarEclipse Wows SkywatchersIn South Pacific