Fifteen Facts about the Moon
The Moon is Earth’s only natural satellite, its nearest large neighbour in space, and the brightest object in the night sky. It controls tides, lights up the darkness, appears in stories and songs, and has even had humans stomping about on it. Here are fifteen facts about the Moon, the big grey companion that seems to follow Earth around everywhere.
The Moon is Earth’s only natural satellite
The Moon orbits Earth at an average distance of about 384,400 kilometres, or 238,855 miles. That sounds far away, but in space terms it is practically next door. About 30 Earth-sized planets could fit between Earth and the Moon.
The Moon is smaller than Earth, but still very large
The Moon has a radius of about 1,740 kilometres, or 1,080 miles, which makes it less than a third as wide as Earth. Even so, it is the fifth largest moon in the Solar System, beaten only by Ganymede (of Jupiter), Titan (of Saturn), Callisto (also Jupiter) and Io (also also Jupiter - the greedy thing!). It is also larger than the dwarf planet Pluto.
The Moon probably formed after a giant impact
The leading explanation for the Moon’s formation is called the giant-impact theory. It suggests that early Earth was struck by a Mars-sized object, throwing material into orbit. That material eventually clumped together and formed the Moon. Evidence that supports this theory is that the composition of materials recovered from the Moon is very similar to Earth’s rocks in several important ways.
The Moon always shows Earth the same face
The Moon rotates once in the same time it takes to orbit Earth, which means the same side is always facing Earth. This is called synchronous rotation, or tidal locking. It does not mean the Moon does not spin; it means it spins at exactly the right speed to keep one side pointed towards Earth.
The opposite side of the Moon is sometimes called the "dark side of the Moon", but that name is misleading because that side receives sunlight just like the side that you see from Earth. It's more accurate to call it the far side of the Moon. Humans first saw the far side in October 1959, when the Soviet spacecraft Luna 3 sent back the first pictures. They were blurry, but they revealed that the far side looks different from the near side, with far fewer large dark plains.
The Moon has phases because of its changing position while orbiting Earth
The Moon does not make its own light. It reflects light from the Sun. As the Moon orbits Earth, we see different amounts of its sunlit half, creating the familiar phases: new Moon, crescent Moon, half Moon, gibbous Moon and full Moon.
If you stood on the near side of the Moon and looked back at Earth, Earth would have phases too, but they would be opposite to the Moon’s. Earth would also stay in roughly the same place in the lunar sky instead of rising and setting, although you would see it slowly spinning.
The Moon has almost no atmosphere
The Moon has no thick atmosphere like Earth. It has only an extremely thin exosphere, which is far too thin to carry sound or create weather. This means the Moon has no wind, no rain, and no blue sky. The sky stays black even during the lunar day.
The Moon is covered in craters
The Moon’s surface is covered in craters caused by asteroids, meteoroids and comets crashing into it over billions of years. Because the Moon has almost no atmosphere, incoming space rocks do not burn up before hitting the surface. The Moon also has no rain, rivers or wind to quickly erase the scars.
Only twelve people have walked on the Moon
So far, only twelve human beings have walked on the Moon. They were all NASA astronauts, spread across six Apollo landing missions between 1969 and 1972: Apollo 11, 12, 14, 15, 16 and 17. The first was Neil Armstrong in July 1969, and the most recent was Gene Cernan in December 1972. That means nobody has walked on the Moon for over 50 years.
Footprints on the Moon can last for millions of years
The Apollo astronauts left footprints in the Moon’s dusty surface. Because the Moon has no wind, rain or flowing water, those footprints are not quickly erased. They can remain for millions of years, although tiny micrometeorites slowly disturb the surface over time.
Humans have left lots of things on the Moon
Apollo astronauts didn’t just leave footprints on the Moon. They also left flags, tools, cameras, scientific equipment, parts of landing modules, three lunar rovers and even two golf balls hit by Apollo 14 astronaut Alan Shepard. Some equipment was left behind to keep working, including laser reflectors that scientists still use to measure the Moon’s distance from Earth. Not only that, many uncrewed probes, landers and rovers have also been launched at the Moon and remain on its surface.
Apollo 11 was the first crewed Moon landing
Apollo 11 landed on the Moon on 20 July 1969. Neil Armstrong became the first person to walk on the lunar surface, followed by Buzz Aldrin. Incidentally, Buzz Aldrin's mother's maiden name was Moon! Michael Collins remained in orbit around the Moon in the command module, keeping it tidy until Neil and Buzz were ready to return to it with their sack of rocks and tales of their day out on the Moon.
The Moon helped change how people understood space
In 1610, Galileo Galilei used a telescope to study the Moon and saw mountains, valleys and craters. This challenged the old idea that heavenly bodies were perfect, smooth spheres. The Moon was not a flawless object floating in the sky. It was a world with lumps, bumps and scars. Galileo also discovered moons orbiting Jupiter, proving that not everything orbited Earth, as many people believed at the time. This sort of thing later got Galileo into serious trouble, because powerful people were not keen on discoveries that challenged what they had been teaching for centuries.
The Moon affects Earth’s tides
The Moon’s gravity pulls on Earth, helping to create ocean tides. The Sun also plays a role, but the Moon has the stronger effect because it is so much closer to Earth. Without the Moon, Earth would still have tides, but they would be much weaker.
The Moon is slowly moving away from Earth
The Moon is gradually drifting away from Earth by about an inch, or 3.8 centimetres, each year. This happens because of tidal interactions between Earth and the Moon. It is not in any rush to leave, but it is slowly increasing its distance.
This also means that total solar eclipses will not last forever. The Sun is about 400 times wider than the Moon, but, at the moment, about 400 times farther away from Earth, so they appear almost the same size in the sky. That allows the Moon to completely cover the Sun during a total solar eclipse. As the Moon moves farther away, it will slowly appear smaller in Earth’s sky. In the distant future, it will no longer look large enough to fully cover the Sun, so total solar eclipses will eventually become a thing of the past.
Humans are planning to return to the Moon
NASA’s Artemis programme is designed to return humans to the Moon and prepare for longer-term exploration. Artemis II carried astronauts around the Moon in April 2026, becoming the first crewed mission to the Moon since Apollo 17 in 1972. NASA’s first Artemis lunar landing is currently planned for 2028.
The aim is not just to visit, take photos, collect rocks, and leave, but to learn how humans might live and work on the Moon for longer periods. A longer term goal is to use the Moon as a stepping stone for future missions deeper into space, including possible crewed missions to Mars.
