The moon may be a lot younger than previously believed, according to scientists using the latest technology to analyze rocks brought back by the Apollo 16 mission nearly 40 years ago. The researchers say the rocks—a kind believed to be the oldest that can be found on the moon—are around 200 million years younger than they expected, making the moon 4.4 billion years old instead of 4.6 billion years old, the Los Angeles Times reports.
Another possibility, the researchers say, is that the magma ocean believed to have covered the moon's surface soon after it was separated from the Earth by a collision with another planet was never there. Other researchers say the team may be jumping to the wrong conclusions, or looking at the wrong rocks, the AP notes. The new theory "is a little bit fancy for my taste," says a scientist who recently published a theory that the Earth once had two moons. (Read more moon stories.)