Transit of Mercury November 8, 2006 Transit start: 2:12pm Sunset: 5:00pm Transit end: 5:10pm Last transit on May 7, 2003 Mercury will look perfectly round and about the same size as a small sunspot. Mercury will appear to be 1/194 of the Sun’s diameter. YOU CANNOT SEE IT WITH YOUR NAKED EYE! True ratio of Mercury’s and Sun’s diameter: 1/286. path today Image copyright Dominique Dierick Distance from Us Sun Close-up of 2003 transit 1 AU (93,000,000 mi) Diameter 1.4 x 109 m (860,000 mi) Mercury 0.69 AU (today) (64,000,000 mi) 4.9 x 106 m (3000 mi) Earth 1.3 x 107 m (8000 mi) You’re standing on it! Websites of interest Image by Royal Swedish Academy of Sciences www.transitofvenus.org/mercury.htm www.exploratorium.edu/transit/ sohowww.nascom.nasa.gov/ Mercury Facts Mercury is the closest planet to the Sun. Rotation period: Atmosphere: Average day temp: Average night temp: 59 d none 710 K (820o F) 80 K (-320o F) Orbital period: 88 days Ave. dist. from Sun: 0.39 AU (36,000,000 mi) Image by Mariner 10, NASA Mercury’s orbit is the most elliptical of all the planets. Today, Mercury is near perihelion, which means it is closest to the Sun. But, that makes it farther from us! Close-up of Mercury’s surface, seen by Mariner 10. It is completely covered by craters. Transit Facts Transits of Mercury only occur when the Sun, Mercury, and the Earth are precisely lined up. Since Mercury’s orbit is tilted slightly, these alignments happen rarely. Transits of Mercury occur approximately 13 times per century. Next transit: May 9, 2016. Last transit: May 7, 2003. Image by NASA/JPL/Northwestern U. www.astro.umd.edu/openhouse