Mercuryis on the fast track! Mercury is the smallest and also the fastest planet in the Solar System. I am the closest planet to the Sun and am named after the messenger to the Roman Gods, whose speed was enhanced by his winged sandals. (Personally, I prefer winged sneakers!) I am the fastest planet in the Solar System, flying around the Sun in a mere 88 days. I race through space at 30 miles per second, outpacing the Earth, who clocks in at just 19 miles a second. Although I am the smallest planet in the Solar System, my large iron core makes me the second heaviest, only slightly lighter than Earth. Although I am the closest planet to the Sun, I am actually not the hottest . . .that honor belongs to Venus with her heat-trapping atmosphere. I'm very hot on the side that faces the Sun, but the other side is always more than 200 degrees below zero! My appearance is similar to the Earths Moon, for I am heavily cratered, lack an atmosphere and have no natural satellites.