Moon 100 million years younger than thought: A new analyses of lunar rocks suggest that the moon is actually between 4.4 billion and 4.45 billion-years-old.

The moon has been believed by scientist for years that is actually 4.56 billion-years-old.Even though a 100 million years off might not be a big deal for something that has been around a few billion years, it's interesting to know when it really came about, making it younger than expected.

Just after the solar system began, it is believed that the moon formed from the lunar rocks that came together from the debris that blasted into space, though when it happened is what makes it more than 100 million years younger than thought.

"There are several important implications of this late moon formation that have not yet been worked out," Richard Carlson, of the Carnegie Institution for Science in Washington, D.C., said in a statement. "For example, 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?" added Carlson, who is presenting the new results Monday (Sept. 23) in London at a meeting organized by the Royal Society called "Origin of the Moon."

When it comes to planets like Earth, Carlson said it's a bit tougher to figure out.

"Ask the same question of the Earth or moon, and you don't get a very precise answer," Carlson said. "Earth likely took longer to grow to full size compared to a small asteroid like Vesta, and every step in its growth tends to erase, or at least cloud, the memory of earlier events."