It is almost perfectly spherical with a diameter of 4,862 kilometers. It is about 58,000,000 kilometers (or about 36,000,000 miles) from the sun, however the planet's orbit is like an elongated ellipse.
Mercury has been known since prehistoric times (3rd millennium BC). Because it appeared as a morning star and an evening star, people gave it two names, Apollo for morning star and Hermes as evening star. However astronomers knew that in fact they were the same body.
Mercury is actually quite similar to our moon. Both of their surfaces are heavily cratered, and display no plate tectonics. There is no sign of recent volcanism.
Mercury has no moons. It has a small magnetic field. The strength is only about 1% of the Earth's magnetic field.
Mercury has been visited by one spacecraft, Mariner 10. Between 1973 and 1974, it flew by three times. Forty-five percent (45%) of the surface was mapped.
Mercury is often visible with binoculars, but because it is very close to the sun, it is very difficult to see in the twilight sky.
Visit some other awesome sites about Mercury!!
NASA's info about Mercury
A quite comprehensive guide to Mercury.
Cool Photo Gallery.
