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Last Post 3/3/2005 3:05 PM by  Kris Sigsbee
eclipses
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3/3/2005 12:49 PM
    LeAnn J can an eclipse be viewed from space?

    Kris Sigsbee



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    3/3/2005 3:05 PM

    Hi LeAnn,

    Yes, eclipses can be seen from space, but what you see depends somewhat on where you are looking. Astronauts on board the Mir Space Station took a photograph of the Moon's shadow moving across the Earth's surface during the August 11, 1999 solar eclipse. This photograph was an Astronomy Picture of the Day and a link to it is below.

    http://antwrp.gsfc.nasa.gov/apod/ap990830.html

    Scientists, such as myself, who use satellite data in our research will often talk about a spacecraft "being in eclipse." Basically, this means that the spacecraft's orbital trajectory has taken it around to the nighttime side of the planet so that the planet is directly between the spacecraft and the Sun, and the spacecraft is within the planet's shadow. If cameras on board the spacecraft were to take photographs of the Sun as the spacecraft entered the planet's shadow, the photographs might look something like photographs of eclipses taken on Earth. Eclipses can be a bit of a problem, as most satellites use solar panels and re-chargeable batteries to power their scientific instruments and other systems. If a spacecraft is going to spend a long time in eclipse, engineers may have to turn off some of the scientific instruments to conserve power and keep vital systems operating.

    Some satellites actually make their own "eclipses." The LASCO instrument on board the SOHO spacecraft simulates solar eclipses by using a small disk to block out the Sun. This allows scientists to view the Sun's corona. The whole SOHO spacecraft is actually still in sunlight, the disk is just a part of the LASCO instrument. You may have seen the small disk in the center of many of the SOHO images of coronal mass ejections (CMEs). We wouldn't be able to see the CMEs very well without using the disk to create an artificial "eclipse." Below is a link to a recent picture from SOHO made using LASCO.

    http://sohowww.nascom.nas...ata/realtime/c3/512/



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