Mercury
In Roman mythology Mercury is known as the god of commerce and the name of the planet closest to the sun. Because it is the closest to the sun it spins the fastest at 30 miles per second. Mercury has been visited by only one spacecraft, Mariner 10. It flew by three times in 1974 and 1975.


Mercury

Mercury is in many way similar to Earth's moon. Mercury is the second densest major body in the solar system, after Earth. Actually Earth's density is due in part to gravitational compression. If not for this Mercury would be denser than the Earth. Using a small telescope Mercury can be seen, even in the daytime. It looks like it is made of 5 to 15 discs. Mercury has no moons. Mercury's interior is dominated by a large iron core whose radius is 1800 to 1900 km. The silicate outer shell is similar to Earth's mantel and crust and only about 500 to 600 km thick. At least some of the core is probably molten. Mercury is a small and mysterious planet with a harsh environment. It is not the place to plan your next vacation.

For more information visit the following sites:

http://www.solarviews.com/eng/mercury.htm

http://seds.lpl.arizona.edu/billa/tnp/mercury.html