An analysis of a moon rock has scientists thinking the moon may be younger than widely believed. They say it's possible that the moon isn't more than 4.4 billion years old or, if not the moon never had the magma ocean that covered its surface after it formed.

The findings published by the journal Nature already has scientists split with some believing the moon is the same age, 4.6 billion years old as they thought and others thinking the moon is actually 200 million years younger. Either way the moon rock brought back by Apollo 16 astronauts show that the moon is much more mysterious than scientists had previously thought.

"It's not as ancient as we might think," said study chief author Lars Borg, a geochemist at the Lawrence Livermore National Lab. His international team of scientists used new techniques and radioactive isotopes of lead to test a sample collected by the Apollo 16 mission and found that the moon rock is actually only 4.4 billion years old. The finding shocked the scientists.

"We all looked at one another and laughed," said Borg.

That means that the moon's magma ocean formed and cooled earlier that scientists had generally thought and that the great impact that formed the moon happened more recently too. The moon is thought to have formed from debris after a planet sized body collided with the Earth 4.5 billion years ago. The moon would have been covered with magma while minerals that were less dense floated to the top and formed the crust. These crustal rocks have been used to determine the point when the moon solidified to become the lunar body floating in the night sky.

Borg proposed another more radical explanation for the younger moon rock that the crustal rock they analyzed didn't form after the magma cooled down. Perhaps the moon never even had a magma ocean and the rocks were formed some other way.

Borg's dating of the moon rock drew praise from other scientist but his analysis garnered criticism. Alex Halliday, an isotope geochemist from Oxford University believes there are less dramatic explanations for the age of the moon rock. The crustal rock could simply not represent the oldest rocks on the surface.

"I hope it's going to cause a real stir," said Clive Neal, a planetary geologist at the University of Notre Dame who was not involved in the study. But, he added, the researchers need much more evidence that other rocks have been inaccurately dated before they jump to radically different theories about the moon's formation.