* Astronomy

Title: Solar eclipses as an astrophysical laboratory
Authors: Jay M. Pasachoff

Observations of the Sun during total eclipses have led to major discoveries, such as the existence of helium (from its spectrum), the high temperature of the corona (though the reason for the high temperature remains controversial), and the role of magnetic fields in injecting energy into - and trapping ionised gases within - stellar atmospheres. A new generation of ground-based eclipse observations reaches spatial, temporal and spectral-resolution domains that are inaccessible from space and therefore complement satellite studies.

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Starting Friday, NASA Television will air video documenting a science expedition to Tripoli and the Sahara desert that studied a total solar eclipse. The international mission was an unprecedented collaboration with Libyan scientists and researchers from around the globe. The video will be broadcast on NASA TV and NASA's Web site on Friday, at 10 a.m. and 2 p.m. EDT.





The March 29, 2006, eclipse lasted more than four minutes at the centre of its path. Most total solar eclipses last two minutes or less. Total solar eclipses are of special interest to astronomers because they are the only time the sun's corona can be seen from the Earth's surface. Observers can detect and measure properties of the sun's outer atmosphere, such as temperature, density and chemical composition, when the light of the disk is blocked by the moon.
The next total solar eclipse will occur Aug. 1, 2008. It will last about two minutes and can be seen in northern Canada, Greenland, Siberia, Mongolia and northern China.

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The International Space Station (ISS) was in position to view the umbral (ground) shadow cast by the Moon as it moved between the Sun and the Earth during the solar eclipse on March 29, 2006. This astronaut image captures the umbral shadow across southern Turkey, northern Cyprus, and the Mediterranean Sea. People living in these regions observed a total solar eclipse, in which the Moon completely covers the Sun’s disk.
The astronaut photograph was taken at approximately 2:00 p.m. local time. The terminator of the eclipse—the line between the light and dark parts of the Sun’s disk— is visible as it passes across central Turkey. This total solar eclipse is the fourth to have occurred since 1999. The portion of the ISS visible at image top is the Space Station Remote Manipulator System.


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The photograph was acquired March 29, 2006, with a Kodak 760C digital camera using a 35 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Centre. The image in this article has been enhanced to improve contrast, and lens artefacts have been removed. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet.

Eclipse coverage and photos from Libya.

http://www.nasa.gov/externalflash/eclipse_front/index.html