Moon by the numbers
238,900miles away on average
1.5 init moves away from Earth each year
27%of Earth's width
12people who have walked on it
All twelve moonwalkers flew on Apollo missions between 1969 and 1972.
Moon facts
Two tides a day
The Moon's pull raises the ocean on both sides of Earth
Same face always
It spins once for each trip around Earth
Mirrors on the Moon
Lasers bounced off Apollo mirrors measure its distance
Born in a crash
Likely formed when a Mars-sized body hit early Earth
The far side
Not the dark side
- The far side gets as much sunlight as the near side
- We just never see it from Earth
- First photographed by a Soviet probe in 1959
Days getting longer
- The Moon's tides slowly brake Earth's spin
- Days grow about 2 milliseconds longer each century
- Hundreds of millions of years ago, days were shorter
Remember
The Moon is drifting away, about as fast as your fingernails grow.
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Answer key
- How far away is the Moon on average?About 238,900 milesAbout 238,900 miles.
- How fast is the Moon drifting away?About 1.5 inches a yearMeasured with lasers and the Apollo mirrors.
- Why do we always see the same side of the Moon?It spins once each trip around EarthThis is called tidal locking.
- Is the far side of the Moon always dark?No, it gets as much sunlightWe just can't see it from Earth.
- How many people have walked on the Moon?12Twelve, on Apollo missions from 1969 to 1972.