Mercury Transit
November 8, 2006
There's a little black spot on the Sun today ... and its name is Mercury. Thirteen times a century Mercury lines up just right to pass between Earth and the Sun, appearing as a tiny dot on the solar disk. November 8, 2006 marks the next occurence of a Mercury transit. The last time this occurred was in 2003 and the next two apparitions will occur May 9, 2016 and November 1, 2019.
Only Mercury and Venus, being closer to the Sun than Earth, can pass inbetween those two solar system bodies and make transits. Venus, which is larger than Mercury, is the easier planet to witness, but its transits are more rare. The next Venus transit is June 6 2012, and then a great absence occurs until a transit in 2117.
The November 8, 2006 event will begin at 2:12 p.m. EST for observers on the East Coast of the United States. The entire transit of Mercury across the face of the Sun takes almost five hours, which means that those in the eastern half of the United States will have the end of the transit cut short by sunset. Those in the western half of the United States will see Mercury end its transit at 4:10 p.m. PST.
Mercury will enter the Sun's disk near the middle of the lower half of the Sun on the left, crossing to the right and moving slightly upward until it exits the disk. Because Mercury is only 1/194th the size of the Sun, viewing the transit will require a telescope. If you have a telescope you can use a solar filter to view the transit firsthand. A Hydrogen-alpha filter may even allow you to see Mercury before it breaches the disk of the Sun. Its dark form may be first observable against the Sun's chromosphere. If you have a telescope but no filter, project the light of the Sun onto a piece of cardboard and watch the dark shadow of Mercury cross in this way. NEVER look through a telescope at the Sun unless you have the proper filtration. Blindness can occur in a fraction of a second.
If you do not have a telescope, there are a few other options to view the transit. Check your local observatory for viewing times. If it's a cloudless day, it is very likely that public observing times will be open for people to get a peek at the transit through the professional telescopes. If none of the above options are available to you, you can watch the transit on NASA's live webcast.
Although many people will have the opportunity to watch the transit during sunset, you will still need properly filtered optical eqiupment to do so. While the sun is generally safe to look at during sunset, it will still be too bright to discern the tiny disk of Mercury on it. Mercury no larger than a sunspot, which are also not visible during sunset.
Good luck viewing, and hope for clear skies!
Mercury Transit
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