Distance Between Earth and Moon | Universe Today

Written by Fraser Cain

The distance between Earth and Moon is 384,399 km, or 238,854 miles.

Keep in mind that this number is an average. The Moon actually follows an elliptical path around the Earth. When it's at its closest point, the distance between Earth and Moon is only 363,104 km. And then when it's out at its most distant point, the distance is 405,696 km.

This is such a big difference that the Moon can look visibly larger and gets much brighter when it's at the closest point in its orbit. When the Moon makes its closest point to the Earth, and this is around the same time that the Moon is at its fullest point, it can look 15% larger and be 30% brighter than when it's not so close.

How can astronomers know how far away the Moon is? During the Apollo missions, astronauts placed a series of reflective mirrors on the surface of the Moon. Scientists on Earth fire a laser pulse at the Moon and time how long it takes for the light to return back to Earth. They can actually calculate the distance between Earth and Moon to within a couple of centimeters.

We've written many articles about the Moon for Universe Today. Here's an article about the discovery of a lava tube on the Moon, and an article about the discovery of water on the Moon.

If you'd like more info on the Moon, check out NASA's World Book on the Moon, and NASA's Lunar and Planetary Science Guide to the Moon.

We've also recorded several episodes of Astronomy Cast just about the Moon. How about this, Episode 113: The Moon, Part 1.

Filed under: Astronomy