The Moon’s distance from Earth can vary between about 225,623 miles (363,104 kilometers) at its closest point (perigee) to about 251,097 miles (405,696 kilometers) at its farthest point (apogee). This variation in distance is due to the Moon’s elliptical orbit around Earth. However, the average distance of 238,855 miles is often used as a standard distance when referring to the Moon’s distance from Earth. (How Far is the Moon)
The distance between Earth and the Moon can be measured in different ways, depending on the purpose of the measurement. Here are a few examples:
- Average distance: As mentioned earlier, the average distance between Earth and the Moon is about 238,855 miles (384,400 kilometers). This value is often used as a standard distance in many astronomical calculations.
- Lunar distance (LD): In astronomy, the term “lunar distance” is used to describe the distance between Earth and the Moon in terms of the Moon’s angular size as seen from Earth. One lunar distance is defined as the distance between Earth and the Moon when the Moon is at its average distance from Earth. This value is about 238,900 miles (384,472 kilometers).
- Center-to-center distance: This measurement takes into account the fact that both Earth and the Moon are spherical objects. The distance between them is measured from the center of Earth to the center of the Moon. The center-to-center distance can vary between about 225,623 miles (363,104 kilometers) at perigee to about 251,097 miles (405,696 kilometers) at apogee.
- Time delay: Another way to measure the distance between Earth and the Moon is by measuring the time delay in radio signals between the two bodies. Because radio signals travel at the speed of light, the time delay can be used to calculate the distance between Earth and the Moon. This method is often used by spacecraft to communicate with Earth from the Moon.
Overall, the distance between Earth and the Moon is constantly changing due to the Moon’s elliptical orbit around Earth. However, the average distance of 238,855 miles is a commonly used value to describe this distance.