The Equator is an imaginary line around the middle of the Earth.

Mercury

Mercury is the second smallest planet and is the planet that is closest to the sun. The only planet smaller than Mercury is Pluto. It is about 36 million miles away from the sun. Mercury is extremely hot during the day, yet extremely cold during the night because it doesn't have an atmosphere to keep its heat from escaping. Mercury is composed of rock and metal. A year on Mercury is 88 Earth days, giving it the shortest year in the solar system. Since Mercury rotates very slowly, a day on Mercury is 59 Earth days. If you could examine Mercury up close it would look just like our Moon, full of craters. These craters formed when rocks from space crashed into it millions of years ago. The only space mission to visit Mercury was Mariner 10, which passed by the planet three times in 1974.

Facts about Planet Mercury:

Diameter: 4,878 km (3,030 miles)

Distance from the Sun: 36 million miles

Diameter at the equator: 3,030 miles

Time take for 1 orbit: 88 days

Temperatures at the surface range between -300 and 800 degrees F.

Related Information about Mercury:

Images of Planet Mercury

Scientists take a closer look at the mysterious side of Mercury

Probe whips past Earth on long voyage to Mercury - August 2, 2005
Earth's first extended visit to the planet Mercury is now one step closer to success after the MESSENGER probe celebrated its birthday one day early on Tuesday with a speedy flyby of its home planet to tweak its course for arrival in orbit in 2011.

Return to Space

Did you know?

When the Moon passes between the Earth and the Sun, it casts a shadow and causes an eclipse.

The Earth is 93 million miles from the Sun.

There is a high and low tide because of our moon and the Sun.

Billions of years from now, the Sun will swell up to become a red giant which in time will shrink to become a tiny star called a white dwarf.