Our Closest Neighbor
Our Moon is a natural satellite. Unlike the robotic satellites that send TV signals and science data back to Earth, natural satellites were there long before people. We just borrowed the name satellite when we first started launching spacecraft into space.
The Moon is smaller than four other moons in our solar system yet is larger than the dwarf planet Pluto. Many spacecraft have been sent to the Moon and 12 astronauts have walked on it.
WHAT'S IT LIKE ON THE MOON?
The Moon is covered with craters. Because it has no atmosphere to protect it, space rocks -- some as big as mountains -- have smashed into it. Tycho Crater is more than 52 miles (85 km) wide! The Moon's surface is rocky and covered with dust. It looks a lot like Mercury.
The Moon's weak gravity means it is easy to move around, even in a heavy spacesuit. It is impossible for people to explore the Moon without a spacesuit. There is no air. And the radiation from the sun is very dangerous.
It gets very hot and very cold on the Moon. When the sun is shining, the Moon sizzles at 265 degrees Fahrenheit (130 degrees Celsius). It can drop down to 170 degrees Fahrenheit (110 degrees Celsius) below zero.