Above is a to scale location representition of Mercury at Sunset.  Each Dot represents 1 Day's Position.  The "W" is Due West on the Horizon.  Note that Mercury, for us, like the Moon and Venus, goes through Phases.

Mercury is "bright". At it's brightest, < Mag. 2.0.  Only the Sun, Moon, Venus, Mars (at it's brightest), and Jupiter are brighter.This Apparition, Mercury will reach Mag. + 0.6.  Not many living people have "seen" Mercury, perhaps only 100,000,000.  That's because, with an Interior Orbit to Earth, Mercury's maximum Elevation at Sunset, for us, above the Horizon, is 28 degrees and usually much lower.  Because it's low in the Twilite Glow, it's difficult to see less than 30 - 45 mins. after Sunset.  Additionally, Mercury is difficult to see if it's Angular Separation from the Sun is less than 12 degrees.

Mercury is a "small" Planet, about one-seventeenth the Volume and Mass of Earth.  It's the fastest Sun-Orbiting Planet - average speed is 30 mi./sec.  Earth's average speed is 18.5 mi./sec.  Mercury has the most Eccentric Orbit of the "Planets" at .21.  At Perihelion (closest to Sun) it's 29,000,000 mi.,  at Aphelion (furthest from Sun) it's 43,000,000 mi.  Mercury gets from 5 to 11 times the intensity of Sun Light as Earth.  Without an Atmosphere, it's even more intense on Mercury's Surface, with an average Surface Temperature of 629 degrees F.

With Earth's and Mercury's Orbits, its Synodic Period is about 116 Days.  Which means it has Eastern Elongations about 116 days, on average.  There's a Western Elongation, on average each 116 Days.  Since I don't like to get up early, I observe Eastern Elongations (when Mercury is visible in the Western Evening Sky after the Sunset).  The next Mercury Eastern Elongations will be Dec. 2010,  Mar. 2011, & July 2011.  I'll probably observe the July 2011 Elongation, maybe the others.

If you want to see Mercury, you'll need a Low Horizon - free of buildings, trees, hills or other obstructions.  At its highest this Apparition, Mercury will be less than 16 degrees above the Horizon at Sunset.  I plan to be at Mt. Pollux, Amhest, Sunday - July 18 & 26, & Friday - July 30, before 8 pm.  Then Friday - Aug. 6 & 20, and Sunday - Aug, 1, 8 15, & 22 by 7:30 pm.  If you want to see Mercury on those dates, please call me, Tom Whitney at  256-6234, between 5 & 6 pm on those dates, or email me at  tom-whitney@tom-whitney.com  , the day before.  I'll meet you and bring extra equipment to Mt. Pollux for this.  If you want to do other dates, notify me at least a day ahead and, if I can, I'll try to accommodate you.

Hope you can "see" Mercury this Apparition.  If so, you'll be in an exclusive group on only 100,000,000 +/- living people.  If you "see" the Cresent of Mercury, you'll be in an even more exclusive group of 10,000,000 +/-, living. 

-  Tom Whitney