Scientists have proposed a shocking new theory for the origin of the moon, and their calculations suggest Earth once had a secret world hiding right next door. Astronomers believe that the moon was ...

Scientists proposed a novel idea on Wednesday that could solve two of the world's mysteries at once—one that passes over our heads every night, and one that sits far below our feet. The first mystery ...

Continent-sized chunks of an alien world may be hiding deep within our planet — and it could explain the weird structures that appear to be surrounding Earth's core. Scientists have long hypothesized ...

There may be chunks of an ancient planet trapped in Earth’s mantle. The prevailing theory of the moon’s formation is called the giant impact hypothesis, in which a Mars-sized object called Theia ...

(CNN) — Scientists widely agree that an ancient planet likely smashed into Earth as it was forming billions of years ago, spewing debris that coalesced into the moon that decorates our night sky today ...

Our moon—or la Luna—has inspired humankind for millennia. It's largely agreed that the moon was created around 4.5 billion years ago when a protoplanet collided with early molten Earth, smashing off a ...

Some 4.5 billion years ago, a Mars-sized rock is theorized to have collided with the proto-Earth. The collision is one of the only ways to create an Earth-Moon system with the properties we observe ...

Scientists widely agree that an ancient planet likely smashed into Earth as it was forming billions of years ago, spewing debris that coalesced into the moon that decorates our night sky today. The ...