Transit of Mercury 

     There will another transit of Mercury across the disk of the Sun on May 9, 2016 ftrom 7:26AM until 2:42PM.    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 of Mercury.  Mercury will have an angular diameter of only 12 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 7:26AM, and mid transit at 10:57AM and ends at around 2:42PM.  The first transit of Mercury was seen through a telescope in 1631 Nobember 7 by Pierre Gassendi (philosopher, priest, scientist, astronomer, and mathematician) in France before the first transit of Venus in 1639 November 24 by Jeremiah Horrocks (cleric, tutor, astronomer, scientist and mathematcian) in England at Much Hoole near Liverpool.
     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 June 8 when the transit of Venus occurred a similar set up was available; we had good weather that morning and more than 500 people saw it that morning as the sun rose.  In the summer of 2012 June 5 we were clouded out from viewing the transit of Venus, but did watch it from Hawaii via the Internet; around 60 people tried with us despite the very cloudy weather.
      There was 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 viewed. because of the clouds on the Internet from the Planetarium, where it is always clear, at the Takoma Park/Silver Spring campus of Montgomery College.  See Fred Espenak, NASA/GSFC, transit of Mercury pages at

Internet Transit of Mercury sites:
Wikipeadia in English

Picture of the Transit of Mercury

Montgomery College's planetarium

Last changed 12:22M June 27, 2012