Earth’s Closest Neighbor

Everyone knows about Earth’s closest neighbor. We see it in the sky almost every night. It is the Moon. The Moon is much smaller than Earth. It is about 2,160 miles (3,475 km) wide. About 50 moons would fit inside Earth.

Our Moon orbits Earth, just as Earth orbits the Sun. The Moon takes about 27 days to travel around Earth.

Like our planet, the Moon also rotates. But it rotates much more slowly than Earth. The Moon takes a little more than 27 days to turn all the way around. Since it travels around Earth in the same amount of time, the same side of the Moon always faces us.

From night to night, the Moon seems to change shape. Sometimes we can see the full moon. Other times, it looks as if it has been cut in half. The Moon’s shape seems to change just a little each night. Over about one month, it grows into a full moon and then gets smaller and disappears again.

We see only the parts of the Moon that are lit by the Sun. As the Moon travels around Earth, sunlight hits the Moon from different directions. When it hits the side of the Moon facing Earth, we see a full moon. If it mostly lights the side facing away from Earth, we see only a sliver.      

The Moon is closer to Earth than any planets are. but it is still very far away.

The Moon may not seem far away. But it is very far. Our Moon is 238,855 miles (384,400 km) from Earth. Imagine you could drive from Earth to the Moon in a car going 50 miles (80 km) per hour. It would take nearly 200 days of nonstop driving to get there.

Once you reached the Moon, what would you see? The Moon’s surface is mostly gray rocks and dirt. You would see some mountains and many deep valleys. You would also see many craters (KRAY-turs). Craters are bowl-shaped pits in the surface. Some craters are just a few miles wide. The largest ones are more than 1,000 miles wide (1,610 km).

Craters are formed when rocks or ice from space slam into the Moon’s surface. These objects are called meteorites (MEE-tee-uh-ryets) and comets (KAH-mehts).

the moon’s surface has craters of many different sizes. these craters are on the side of the moon that faces away from Earth.

What else would you notice? There is no life on the Moon. The Moon has almost no atmosphere. So there is no air to breathe. Without an atmosphere, nothing protects the Moon from the Sun’s heat. Nothing holds in any of the Sun’s warmth either. So the Moon gets very hot and very cold. Sunny parts of the Moon get as hot as 253°F (123°C). Other places get as cold as –387°F (–233°C).