Our Moon: The Stranger We Know in the Sky

We look at the moon so often that we don't even think about it anymore. It rises and sets like clockwork, going through its phases. But if you think about it for a minute, you'll see how truly strange and interesting our closest cosmic neighbor is.

The moon is about 238,855 miles away from Earth on average, which is close enough that it only took Apollo astronauts three days to get there. It formed about 4.5 billion years ago, not long after Earth itself. The most common scientific explanation is that a Mars-sized body called Theia hit the early Earth, and the debris from that terrible collision eventually came together to form the moon we see today. That's not a myth; it's what the chemistry of lunar rocks strongly suggests.

The size of the moon compared to Earth is one of its most underrated features. Our moon is bigger than the planet it orbits. Most moons in the solar system are very small compared to the planets they orbit. Ours is about 25% the size of Earth. Some scientists even call the Earth-moon system a "double planet," which changes how you think about where we live.

That size is more important than you might think. The moon's gravity keeps Earth's axial tilt stable, keeping it at about 23.5 degrees for long periods of time. If the moon weren't there, Earth's tilt could change a lot, which would lead to climate changes that could change life on Earth. The moon is more than just a pretty sight. In a real sense, it has protected the Earth from becoming unlivable.

And then there are the tides. The moon's gravity pulls on the oceans of Earth, which makes the tides that have changed coastlines, affected marine ecosystems, and helped sailors for thousands of years. The moon is the main cause, but the sun also has an effect. The higher spring tides happen when the moon, Earth, and sun are all in line. When they make a right angle, the neap tides that are less strong come next.

There are signs of violence on the surface of the moon. The dark spots that can be seen from Earth are huge flat areas of solidified lava called maria. They were formed billions of years ago by volcanic activity. The rest of the surface is covered in impact scars, some of which are billions of years old. These features don't go away because the moon doesn't have an atmosphere and not much geological activity. The moon's past is clear to see.

There is also ice water on the moon, in craters near the poles that are always in the dark and never get any sunlight. This discovery, which has been confirmed in the last few decades, has changed how scientists and space agencies plan to explore the moon in the future. In theory, that ice could be turned into drinking water or even rocket fuel.

We sent 12 people to walk on the moon's surface, all between 1969 and 1972. Since then, no one has returned. That gap is one of the strangest things that has ever happened in the history of human exploration. It may not last much longer since several agencies are now working to get back there.