That old moon might not be as antique as we thought, some scientist think. They say it's possible that it isn't a day over 4.4 billion years old. But other astronomers disagree with a new study's conclusions. They think the moon is up to its typical age-defying tricks and is really pushing 4.6 billion as they have suspected all these years. 
 
 FILE - In this Thursday, July 21, 2005 file photo, the full moon rises behind the ancient temple of Posseidon, in Sounio about 73 kilometers (45 miles) southeast of Athens. That old moon might not be... (Associated Press) 
 
 Either way, the new analysis of an important moon rock brought back by the Apollo 16 mission is showing that the moon isn't ready to give up its true age and origins quite yet, even though scientists thought they had it all figured out a decade or two ago. 
 
 "It's not as ancient as we might think," said study chief author Lars Borg, a geochemist at the Lawrence Livermore National Lab. His study appears online Wednesday in the journal Nature. 
 
 The study uses new techniques and radioactive isotopes of lead and other elements to date the moon rock at 4.4 billion years old. What's key is that this is a special type of rock that would have floated up to the moon's crust soon after its theorized ocean of molten rock cooled. That supposedly happened soon after the moon formed as a result of a spectacular crash between Earth and a planet. The chunks that broke off formed the moon. 
 
 That means there are two possibilities, Borg said. Either the moon is 200 million years younger or the accepted theory of a molten rock ocean on the moon is wrong, he said. 
 
 Borg acknowledges that some moon rocks have been dated at nearly 4.6 billion years old. But those conclusions could be wrong because of weaker rock dating techniques used in the past, he said. 
 
 Outside scientists said Borg did good work coming up with a date for the Apollo 16 rock but may have jumped to the wrong conclusion on lunar age or origins. They said it's possible that the rock is from a smaller molten rock ocean or was created when the moon was bombarded by space debris which was much more common a few billion years ago. 
 
 Borg's conclusion "is a little bit fancy for my taste," said Erik Asphaug of University of California, Santa Cruz, who recently published a theory that Earth used to have a second smaller moon until it crashed into the bigger one. 
 
 MIT astronomer Maria Zuber called the study in Nature "very puzzling." 
 
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 Nature: www.nature.com 

 The moon may be 200 million years younger than widely believed, according to a new analysis of a rock brought back to Earth in 1972 by Apollo 16 astronauts. Or, if not, the moon may never have had the magma ocean that scientists think covered its surface soon after it formed.Either way, the findings published online Wednesday by the journal Nature could send lunar scientists back to the drawing board to reconsider the moon's evolution.The moon is thought to have formed from debris ejected into space after a Mars-sized body collided with the still-molten Earth about 4.5 billion years ago. The young moon would have been hot and blanketed by magma. But without a thick atmosphere to trap its heat, the molten rock cooled relatively quickly, while minerals that were less dense than the magma floated to the top first, forming the moon's crust. These rocks give the white highlands of the moon's near side their pale hue, and have been used to determine the point at which the moon solidified into the body we know today.But an international team of scientists decided to use sophisticated techniques to bettertest a sample collected by the Apollo 16 mission — one that was considered one of the oldest moon rocks and that would, with any luck, provide an accurate age because it is relatively unscathed by meteoric impacts.Planetary scientists can determine a rock's age by calculating how many radioactive "parent" isotopes of a particular element have decayed into "daughter" isotopes. But rather than test the radioactive decay using just one method,the researchers used three, involving the elements lead, samarium and neodymium. Because different isotopes decay at different rates, each method provided a slightly different measuring stick.All three calculations resulted in very similar ages: an average of about 4.36 billion years, which surprised the scientists. "We all looked at one another and laughed," said lead author Lars Borg, a geochemist at Lawrence Livermore National Laboratory in Northern California.If that is correct, it means the moon's magma ocean formed — and cooled — more recently than scientists have generally thought was the case based on evidence from meteoritescontaining some of the oldest minerals in the solar system. This also could mean that the great impact that separated the moon from Earth happened more recently too.The study authors propose another, more radical, explanation: The crustal rock they analyzed, called ferroan anorthosite, is not linked to magma dynamics at all. Perhaps the moon never even had a magma ocean and the rocks were formed another way, they suggested."You're left with picking your poison," Borg said.The new dates could leave scientists who model the moon's formation "scratching their heads," said Alex Halliday, an isotope geochemist at Oxford University who was not involved in the study. "It's a little bit awkward, because nobody likes to say, 'They've got their data wrong.' "But there are less dramatic explanations, Halliday said, including the possibility that both these and previous dates are right, and the ferroan anorthosite examined in this study simply does not represent the oldest rocks on the lunar 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.
– 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.