This image shows the Earth and Mars
The Formation of the Moon
Any successful theory must account for everything we know
Moon now, as well as make predictions about future observations. There are three theories about how the moon came to be in place:
- that the moon came out of the crust of the Earth
- that the moon was captured by the Earth
- that the Earth and moon formed together out of the primordial nebula
By whatever means it came to be in place, as the Moon finished forming, about 4 billion years ago, the surface was hit by the remains of the boulders which are thought to have formed the Earth, until the boulders were completely gone. During this time the moon warmed and experienced volcanism. There is abundant evidence of volcanic plains from this time period. Toward the end of the period of bombardment by boulders, scientists think that the Moon was hit by a series of very large boulders. These collisions formed what we know today as the lunar Maria.
Because of its small size, the Moon would have cooled very rapidly compared with the Earth. Soon, the Moon cooled completely to the form we see today. Surface activity in the form of plate tectonics and other forms of surface activity ceased once the Moon cooled. Even the interior of the Moon seems to have cooled to the form of inactivity today.
Shop Windows to the Universe Science Store!
Learn about Earth and space science, and have fun while doing it! The games
section of our online store
includes a climate change card game
and the Traveling Nitrogen game
You might also be interested in:
How did life evolve on Earth? The answer to this question can help us understand our past and prepare for our future. Although evolution provides credible and reliable answers, polls show that many people turn away from science, seeking other explanations with which they are more comfortable....more
Any successful theory must account for everything we know about the Moon now. Those things include the moon seems to be made of the same material as the Earth's upper mantle. the Moon has little or no...more
A Planet or a moon cools off slowly in time, just like the sidewalk cools off in the evening after a sunny day. The warmth contained inside a planet or moon controls what sort of activity the planet or...more
Unlike the icy moons of the outer planets, the moons of the Earth and Mars are rocky moons. We said already that the moons of Mars are probably captured asteroids. In a moment we will discuss the fact...more
Scientists used the Lunar Prospector spacecraft to find out that the Moon has a small core. The Moon's core is a lot smaller than the Earths' core. This helps scientists prove that the Moon formed from...more
The Earth may only have one Moon, but it's a big one! The Earth's Moon is the fifth largest in the whole solar system. But it is still smaller than the Earth, so objects weigh less on the Moon than they...more
Although the Moon does not appear to have a magnetosphere surrounding it, it *is* a magnetic object in space. Scientists think that the magnetism of the Moon's surface is leftover from a time when the...more
The atmosphere of the Moon may come from a couple of sources, one source is outgassing which means gases coming from deep within the Moon. Gases are released from the interior of the Moon during moonquakes....more