Nell Greenfield Boyce

Astronauts brought back moon rocks, and almost all date back to around 4.35 billion years ago. Trouble is, scientists think the moon got created much earlier than that, when an object the size of Mars slammed into the Earth. Now, in the journal Nature, researchers offer this explanation.

Astronauts brought back moon rocks, and almost all date back to around 4.35 billion years ago. Trouble is, scientists think the moon got created much earlier than that, when an object the size of Mars slammed into the Earth. Now, in the journal Nature, researchers offer this explanation.

As the moon moved away from Earth, at a certain point, it underwent a temporary period of remelting due to gravitational forces that heated it up. Francis Nimmo is with the University of California, Santa Cruz.

As the moon moved away from Earth, at a certain point, it underwent a temporary period of remelting due to gravitational forces that heated it up. Francis Nimmo is with the University of California, Santa Cruz.

Creating new rocks that appeared to be younger than the true age of the moon. Nell Greenfield Boyce, NPR News.

Creating new rocks that appeared to be younger than the true age of the moon. Nell Greenfield Boyce, NPR News.