Mercury
Mercury is 1,515 mi and is smaller than earth.
During the night, Mercury is usually -279 degrees F and during the day it's usually 801 degrees F.
Mercury does not have any weather like storms, clouds, wind, or rain. Sense It's so close to the sun, It's extremely hot or really cold at night.
It takes Mercury 1,407.5 hrs to turn around which is about 59 earth days and it takes 88 days to orbit the sun. About every seven years you can see Mercury from Earth passing the face of then sun. The next time we can see Mercury is May 9, 2016.
Mercury's surface is jumbled and heterogeneous. If you could stand on Mercury, you would experience 38% the force of gravity that you would on Earth.
Mercury is essentially a large metal ball and composed mostly of heavy elements, mainly iron. 75% of Mercury is It's core and a very thin crust.
The date Mercury was discovered is unknown but they believe It was first mentioned around 3000 B.C. by the Sumerians and was being observed for thousands of years. It was named after a Roman Messenger God because It was the fastest planet to orbit the sun.
Interesting facts
Mercury has a molten core.
Only 2 spacecrafts have ever visited Mercury