Basic Motion of the Moon (49)

Introduction

The aim of this post is to describe very simply the basic details of the Moon’s motion around the Earth.

Elliptical Path and Near Side

The moon moves in an elliptical path around the Earth, completing its orbit every 29 Earth days. This coincidently is the same time it takes the Moon to rotate once on its axis. Because of this from the Earth we only ever see one hemisphere or face of the moon. This face or hemisphere is commonly referred to as the near side.

Far Side

The other side, the dark side is permanently hidden from our view here on Earth. We got the first glimpse of the fur or dark side of the Moon in 1959 when the soviet spacecraft Luna 3 managed to photograph it.

Perigee and Apogee

Because the Moon orbits the Earth in an elliptical orbit the distance between the Moon and the Earth varies. There is a time when the distance between the Earth and the Moon reach a maximum and a minimum.

When the Moon is closest to the Earth it is said that the moon is at its perigee, and when the Moon is furthest it is at its apogee.

The perigee is 356410km away from the Earth, and the apogee is 406 697km away. This variation in distance of the Moon from the Earth makes the Moon look smaller and larger in the night sky.

Conclusion

The most interesting thing about eh Moon’s motion around the Earth is that the rotation of the Moon around its axis is synced to its rate of revolution around the Earth, making only one of its sides always visible to us.

End (49).