Transit of Mercury

     There will be a visible transit of Mercury across the disk of the Sun in the Washington DC Metro area on Wednesday, November 8, 2006 a little after 2:00 PM until sunset ( around 5:00 PM), which we will view because of the rain and clouds on the Internet from the Planetarium, going to some place that it is clear, at the Takoma Park/Silver Spring campus of Montgomery College.  See Fred Espenak, NASA/GSFC, transit of Mercury pages at
     There will not be another transit of Mercury across the disk of the Sun until May 9, 2016.  The previous transit of Mercury was on May 7, 2003.  There are approximately 13 Mercury transits per century.  Telescopes with solar filters will be pointed at the sun to view any sunspots and the transit form 2:00 PM until sunset.  Mercury will have an angular diameter of 9.95 arcsec; the Sun will have an angular diameter of 31 arcmin and 17 arcsec.  This means that Mercury will be 0.005 times smaller than the sun in angular diameter.  First contact is at 2:12 PM, and second contact (when the whole planet covers a small part of the Sun) occurs at 2:14 PM.  The greatest transit occurs at 4:41 PM, but the Sun will be only approximately 3 deg above the horizon (compensating for refraction of the atmosphere) and may be behind a building.
     If it is cloudy we will still hold the event, but we will view the event from the first floor of the parking garage instead of the roof of the parking garage.  This will be possible with a computer with an internet connection to a telescope further west, where it will be clear, a video projector, and a screen.  In the summer of 2004 when the transit of Venus occurred a similar set up was available, but good weather that morning made it unnecessary. 

Internet Transit of Mercury sites:
Nasa Digital Learning Network
Exploritorium Transit in San Francisco
Hawaiian Webcast of the Transit
Space Weather
Kochi, Japan

Picture of the Transit of Mercury

Montgomery College's planetarium

Last changed 4:29PM November 16, 2006