Did Earth steal the Moon from Venus?

By Casey Frye, CCNN Writer

Moon and Earth
A new scientific theory suggests that the Moon came from Venus!

Do you ever stare at the Moon right before going to bed and wonder where it came from? If so, you’re not the only one; there are a handful of theories that attempt to explain why Earth has a moon. According to the latest one, it was stolen from the planet Venus!

I know that sounds a bit weird, but it’s certainly no more strange than some of the other theories out there. For example, some scientists say that an object the size of a planet crashed into a young Earth. The impact was so strong, that a hefty chunk broke apart and drifted into space, but not before it was caught by Earth’s gravity.

The problem with this theory, though, is that scientists just don’t know where the Earth-breaking, planet-sized giant came from. Was it a moon from another planet? Was it an enormous asteroid? It’s hard to say, so there are other explanations that attempt to trace the origins of the Earth’s natural satellite.

In another theory, known as “Moon capture,” scientists believe that an object was hurtling through space and got caught in Earth’s gravity. However, the problem with their theory is that the chemicals found on the Moon are too similar to those found on Earth. What are the chances that an object from the far reaches of space are just like the ones on our planet? Not very much.

Well, you know what planetary body is also very similar to Earth and the Moon? Venus, and that’s where researchers now believe the Moon came from. Alex Halliday, head of science at Oxford University, explains the basic ideas of how the Earth got its Moon from Venus. “The reason why it’s interesting is that Earth and Venus are close to each other. They have similar mass, and people think they have probably formed in a similar way,” he said. “So the question is, if Earth and Venus formed in similar ways, how come the Earth has a Moon and Venus doesn’t?”

In order to further support the theory, they’ll need to find out what chemicals Venus is made out of. If they’re the same as those on the Moon and on Earth, then the “Moon capture” theory will definitely be more likely. “I think part of the key to [understanding] the Moon may be that Venus has no moon, and we certainly have to study [Venus] more,” said Dave Stevenson, professor of planetary science at Caltech University, who came up with this new idea.