Did Earth Get its Moon from Venus?

Researchers are suggesting that earth might have borrowed the moon from Venus!

Moon is our nearest cosmic body and astronomers have spent decades studying its composition, yet nobody is sure about the origins of moon.

The most popular theory about the moon's origin is that a proto-planet collided with early earth about 4.5 billion years ago, which resulted in rocks flying out to space. Some rocks fell back to earth, while others got together and formed the moon. However, some astronomers believe that the story isn't this simple.

Dave Stevenson, professor of planetary science at the California Institute of Technology, recently proposed the Venus moon hypothesis at the Origin of the Moon conference at the Royal Society

"I think part of the key to [understanding] the moon may be that Venus has no moon, and we certainly have to study it (Venus) more," Stevenson told Space.com.

Not everybody is buying Stevenson's idea. Previous studies on rock samples from the moon have already shown that its isotopic composition is similar to the rocks found on earth. The isotopic similarity indicates that it was a collision that triggered the formation of moon.

Alex Halliday, head of science at Oxford University, does not support the Venus moon hypothesis. However, Halliday says that the idea itself is very interesting.

"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 told Space.com. "So the question is, if Earth and Venus formed in similar ways, how come the Earth has a moon and Venus doesn't?"

Other theories of moon formation

There are many hypotheses explaining the origin of moon. One of them is the giant impact hypothesis, which says that a proto-planet collided with early earth that created the moon. Another one is the co-formation hypothesis that states that both earth and moon were created together.

Stevenson himself favors the giant impact hypothesis, but says that until we study the chemical composition of Venus, we can't be sure about the origins of moon.