For lists of Mercury Transits visit Dr. Fred Espenak's page. The next one will be on May 7, 2003. There will be a transit by Venus on June 8, 2004.
Copyright 1997 Dr. Sten Odenwald
Return to Ask the Astronomer.
The orbits are inclined to the Earth's orbit and their sizes are so small that the timing has to be exactly right for them to pass through the ecliptic plane exactly at the time when the ascending/descending node is between the Sun and the Earth. For mercury, they happen every 5-10 years. For Venus they are considerably rarer. The November 15, 1999 transit of the Sun by Mercury was observed by the NASA Trace satellite which returned some excellent images and movies. NASA/ESO's SOHO observatory also had a ring side seat and produced several more images and movies.
For lists of Mercury Transits visit Dr. Fred Espenak's page. The next one will be on May 7, 2003. There will be a transit by Venus on June 8, 2004.
Copyright 1997 Dr. Sten Odenwald
Return to Ask the Astronomer.