The Moon

Like Earth, the Moon consists of three main layers: a crust, a mantle, and a core. 

Billions of years ago, the Moon was a molten world. As it solidified, the heaviest materials (metals like iron) sank down into the Moon’s center, and the lighter materials (lower density rocks) rose towards the surface. The result is a structure a bit like a chocolate-dipped cherry – solid core, mostly solid/partly liquid mantle, and thin outer crust.  

Yes, but just barely.

In contrast to Earth’s thick layers of air, the Moon’s exosphere is a bit like the haze you get when you whack a dirty rug with a broom: it includes a sampling of particles knocked free by impact. But instead of a rug, these particles come from the lunar surface. Instead of flying through the air, they’re ejected into near-emptiness. And instead of a broom, the Moon is pummeled by space debris.

Earth's Moon is covered in craters.

Lunar craters tell us the history not only of the Moon, but of other worlds, too. On the Moon, where there’s no liquid water or wind, evidence of our solar system's impact history has been preserved for billions of years.

Earth's view of the half-sunlit Moon shifts throughout the month.

As our perspective changes, we observe a pattern known as lunar phases: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent.

Earth’s Moon was born out of destruction.

There are several theories about our Moon’s formation, but almost all share this point in common. Our early solar system was the scene of violent smashups that could end in obliteration or new, larger objects. Those mashed-together objects make up the planets, moons, asteroids and other solar system objects we know today.

There’s water on the Moon.

Ancient ice hidden deep in permanently shadowed craters. H20 molecules on the sunlit lunar surface. Humanity's search for water on the Moon began hundreds of years ago. Here's a brief history of discoveries leading up to the confirmation of its presence.