No wonder the moon has such a youthful complexion (well, it vaguely resembles a teenager's spotty face)—new research suggests it isn't quite as old as previously thought. The standard theory was that the moon formed some 4.56 billion years ago, after another planet slammed into Earth. But a new analysis by a geochemist at the Carnegie Institution for Science suggests the rock is actually somewhere between 4.4 billion and 4.45 billion years old, reports Space.com.
"Back in the 1970s, you couldn't distinguish between 4.45 and 4.55 billion years," says the scientist, Richard Carlson, per the LA Times. "Today, we can, and everything we are seeing suggests the 4.4 billion number." That raises "several" new questions, notes Carlson. "For example," he tells Space.com, "if the Earth was already differentiated prior to the giant impact, would the impact have blown off the primordial atmosphere that formed from this earlier epoch of Earth history?" (Read more moon stories.)