How Far Away Is the Moon?

How many Earths fit between Earth and the Moon?

Drawings often show Earth and the Moon close together, which hides how wide the gap really is.^[2] NASA gives the average distance as 384,400 kilometers (238,855 miles), and some of its pages round that to about 385,000 kilometers (239,000 miles).^[1][5] At the average distance, 30 Earth-sized planets could fit between the two.^[1]

NASA's Space Place offers a scale model to try: if Earth were the size of a basketball, the Moon would be the size of a tennis ball, placed 23 feet 9 inches from the middle of the basketball.^[2]

Why does the Moon's distance from Earth change?

The Moon is not always the same distance from Earth, because its orbit is not a perfect circle.^[2][3] The path is elliptical, and during every 27-day orbit the Moon passes through a closest point, called perigee, and a farthest point, called apogee.^[3] NASA Science gives perigee as about 363,300 kilometers (226,000 miles) and apogee as about 405,500 kilometers (251,000 miles).^[3]

NASA pages do not all quote the same figures: Space Place lists 225,309 miles for the closest distance and 251,903 miles for the farthest, a little different from the rounded numbers above.^[2][3] By its count, the gap is between 28 and 29 Earths wide at the closest point and almost 32 Earths wide at the farthest.^[2] The chart below uses the Space Place figures, in miles.^[2]

• Closest225,309 miles
• Average238,855 miles
• Farthest251,903 miles

Source: NASA Space Place [2]

The closest and farthest distances are also not the same on every orbit.^[3] NASA's Moon Fact Sheet notes that its perigee and apogee values are means, and that the orbit changes over the course of the year, so the distance roughly ranges from 357,000 km to 407,000 km.^[4] NASA Science adds that the exact distances vary because the Moon's orbit wobbles and differs depending on where the Sun and Earth are in their own orbits.^[3]

A full Moon that coincides with perigee is called a supermoon.^[3] At its closest point, a full Moon can appear up to 14 percent bigger and 30 percent brighter than the faintest Moon of the year, which occurs when the Moon is farthest from Earth.^[3] Because the Moon is then at its closest approach, it can also cause higher tides than usual.^[3]

How long do light and spacecraft take to reach the Moon?

NASA's Glenn Research Center describes the Moon as about 1.3 light-seconds away.^[8] In practice, people on Earth see the Moon as it was 1.3 seconds ago.^[8] A laser pulse fired at a reflector on the Moon takes about 2.5 seconds on average to bounce back to Earth.^[6]

Spacecraft need days rather than seconds.^[7] Apollo 11 launched on July 16, 1969, and an engine firing about 75 hours and 50 minutes into the flight placed it in orbit around the Moon on July 19.^[7] Neil Armstrong stepped onto the surface about 109 hours and 42 minutes after launch.^[7]

How is the distance to the Moon measured?

The distance is measured with lunar laser ranging, which relies on reflectors left on the Moon, starting with arrays that Apollo astronauts set up.^[5][6] The method is simple in principle: aim a beam of light at a reflector and time how long the light takes to come back.^[6]

A 2020 NASA article counted five reflecting panels on the Moon.^[6] Apollo 11 and Apollo 14 crews delivered two of them in 1969 and 1971, Apollo 15 astronauts left a third in 1971, and the Soviet robotic rovers Lunokhod 1 and 2, which landed in 1970 and 1973, carry the other two.^[6] The Apollo 11 and 14 arrays each hold 100 quartz glass prisms called corner cubes, and the Apollo 15 array holds 300.^[5] These mirrors reflect light back in the direction it came from, and the arrays need no power.^[5][6]

At least one newer reflector has joined them since.^[9] In March 2025, NASA reported that its Next Generation Lunar Retroreflector, carried to the Moon by Firefly Aerospace's Blue Ghost lander, had already returned laser light from two lunar laser ranging observatories.^[9]

A 2019 NASA article describes four telescopes, at observatories in New Mexico, France, Italy and Germany, that fire lasers at the arrays and time each pulse's trip to the reflectors and back.^[5] The timing gives the distance to within a few millimeters.^[5][6]

Only a tiny share of the light completes the trip.^[6] A beam about 10 feet wide on the ground spreads to more than 1 mile (2 kilometers) across by the time it reaches the Moon, and a photon launched from Earth has a one-in-25-million chance of reaching the Apollo 11 reflector.^[6] The chance that a photon which reaches the Moon will make it back is lower still: one in 250 million, according to some estimates.^[6]

Is the Moon moving away from Earth?

Yes: lunar laser ranging shows that the distance between Earth and the Moon increases by 3.8 centimeters (1.5 inches) a year.^[5][6] A NASA article compares this to the rate at which fingernails grow.^[6] NASA's Moon Facts page states it more loosely, as about an inch each year.^[1]

NASA links the drift to tides in Earth's oceans.^[5] There are two tidal bulges, and the gravitational force between those bulges and the Moon slows Earth's rotation while pulling the Moon forward along its orbit.^[5] That forward force makes the Moon spiral away from Earth by about 3 millimeters (0.1 inches) each month.^[5]