21 October 2010
Credit: NASA
On 7 October 2010, from its vantage point in space, NASA’s Earth-orbiting Solar Dynamics Observatory (SDO) spacecraft imaged a solar eclipse that was not visible in Earth, when the Moon passed between the Sun and the spacecraft. This phenomenon, which resembles the normal solar eclipses that can be observed from Earth, is termed lunar transit.
Like eclipses, transits occur when a celestial body moves in front of another. In transits, however, the transiting body is often markedly smaller in apparent size than the transited body. Examples of transits include the rare transits of the planet Venus. During transit, Venus is visible as a black dot, creeping across the dazzling Sun disk.
Caution: Never look at the Sun with your eyes or through any optical aids. The Sun can be observed only through special scientific equipment. Observe the Sun only under the supervision of astronomy specialists.
SDO was launched on 11 February 2010, aboard an Atlas V rocket, from the Cape Canaveral Air Force Station. Its 5-year mission is part of NASA’s Living With a Star program. SDO will study the influence of the Sun on Earth and the space environment around our planet, by observing the solar atmosphere in various radiations. SDO will particularly focus on the origin, structure and phenomena of the Sun’s magnetic field. It is orbiting in a circular geosynchronous orbit, at an altitude of about 36,000 km. At this altitude, a satellite orbits Earth once a day.
References
NASA
www.nasa.gov
Wikipedia
Further Reading
NASA’s SDO Mission Homepage
http://www.nasa.gov/mission_pages/sdo/main/index.html
Aymen Mohamed Ibrahem
Senior Astronomy Specialist