Mercury

After a six and a half year journey, NASA's MESSENGER spacecraft finally entered orbit around Mercury.

A few interesting factoids from NASA...

• MESSENGER lifted off from Cape Canaveral Air Force Station, Fla. on August 3, 2004.
• To reach Mercury orbit, the spacecraft traveled 4.9 billion miles.
• The spacecraft circled our Sun 15 times before it settled in Mercury orbit.
• MESSENGER is only the second spacecraft sent to Mercury and the first to enter its orbit. The last one - Mariner 10 [which flew by Mercury] - completed its mission in 1975.
• Mercury is the smallest and least explored of our solar system's inner planets.
• The day side of Mercury can broil at 800 degrees Fahrenheit; the night side drops to minus 300 degrees.
• Messenger's mission will last only two days — two Mercury days, that is. Because Mercury rotates on its axis so slowly, one Mercury day is equivalent to about 176 days here on Earth. Mercury zips around the sun very quickly, taking just 88 days to complete one orbit. So during Messenger's 12 Earth months of orbital observations, the spacecraft will experience just two Mercury days but more than four Mercury years. [I'm still trying to figure that one out!]