SPACE.com -- Mercury Transits Sun, Images on Web

Mercury nears the limb of the Sun just prior to the end of the transit in this image taken by a telescope on the Canary Islands, off the coast of Africa.

Mercury is a lonely dot against the huge solar disk in this SOHO image of the 2003 transit event.


	Mercury Transits Sun, Images on Web By Robert Roy Britt Senior Science Writer posted: 09:01 am ET 07 May 2003

HP image story for Tuesday 5/6

The planet Mercury made a rare transit across the Sun today as skywatchers across much of Earth watched through special telescope set-ups or on the Internet.

Mercury appeared as a mere dot against the huge Sun. The planet's apparent size was about 1/160^th that of the solar disk.

The best views were from Asia, Africa and Europe. The transit was underway as the Sun rose in the eastern United States.

Telescopes in several locations captured the event and posted images on the Web. Remarkable views were provided by the Swedish 1-meter Solar Telescope (SST) of the Royal Swedish Academy of Sciences. The SOHO spacecraft, operated by NASA and the European Space Agency, captured images from about 1 million miles away (1.6 million kilometers) in a location between Earth and the Sun.

The transit occurred because Mercury is closer to the Sun than Earth. Because of orbital configurations, however, only about 13 take place each century.

SOHO (Solar and Heliospheric Observatory) provided an image every minute from its MDI (Michelson Doppler Imager) camera. Engineers plan to use the event to calibrate SOHO's subtle movements in space.

Otherwise, astronomers had not planned any significant science for the event, which was seen as a warm-up for an even rarer transit of another inner planet next year. Venus has not transited the Sun, as seen from Earth, since 1882. It will do so on June 8, 2004.

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