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Tuesday, October 17, 2006

Heads up! Transit of Mercury on November 8th

Having accomplished my life-long goal of observing a transit of Mercury in 2003 (and then the spectacular transit of Venus a year later), I'd be amiss if I didn't alert readers in the Western Hemisphere and East Asia to the upcoming transit of Mercury on November 8th, 2006.

Almost any observer in the Western Hemisphere with a clear sky can see this event (those in Eastern longitudes in the Americas will see the Sun set with the transit in progress, and folks in East Asia will see the Sun rise with the transit already underway—see the summary map for details).

Unlike a transit of Venus, which can be glimpsed with the unaided eye through a safe solar filter, in a November transit the disc of Mercury subtends only ten arc seconds: well below the unaided visual acuity of any human. This means that to observe the event, you'll need a telescope with a safe solar filter, since you'll be aiming directly at the Sun to observe the transit. I have had great results with the full aperture solar filters from Orion Telescope and Binoculars, but there are many other vendors with excellent products to choose from.

If you miss this event, you'll have to wait until May 9th, 2016 for the next transit of Mercury. Venus will transit the Sun on June 6th, 2012, for the last time until the 11th of December 2117. Immortals with unrestricted space and time travel capability may wish to visit our Quarter Million Year Canon of Solar System Transits to plan their transit-watching excursions in the past and future.

Posted at October 17, 2006 01:28