Ned Potter is the science correspondent for ABC's "World News with Charles Gibson." He has reported on such topics as space exploration, the human genome and climate change.
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By the Light of the Silvery Moons
May 08, 2008 8:05 AM
The Earth had a really bad day about 4.5 billion years ago. Something about the size of Mars, so the theory goes, hit our still-forming planet, spewing debris in all directions. Much of that material eventually coalesced to form the Moon.
Or maybe, say two scientists, it formed several moons.
Jack Lissauer of NASA's Ames Research Center and John Chambers of the Carnegie Institution of Washington have published a paper in the journal Icarus -- read the abstract HERE -- in which they do the math and conclude that debris could stay put for tens of millions of years at two of the so-called Lagrange points, places about a million miles from Earth where the gravity and the Earth and Moon effectively cancel each other out.
The Lagrange points have proved useful to managers of space missions; the SOHO solar observatory floats in one of them. But entire moons, even small ones?
Lissauer and Chambers say it's possible -- and given the eons they calculate debris could have stayed put, pieces of debris could have pulled together under the force of gravity to form moonlets.
Whether this actually happened is conjecture; the Lagrange points are empty now. The gravity of other planets would have been enough to destabilize objects there over time.
Ker Than of New Scientist has posted a short musing on the possibility, quoting Matija Cuk of the University of British Columbia, who's done similar modeling.
"They would have looked more like Jupiter or Venus in the sky than a satellite," said Cuk. "They would have resembled very bright stars."
Hat tip to Tuan Nguyen of our staff for noticing this.
May 8, 2008 | Permalink | Share | User Comments (23)
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My father happened to see an episode sometime last week and we were interested in receiving more information. It had to do with a study that NASA is doing regarding sleep. It showed a 3 month study in which the individual would recieve money for the study. Please contact me with any information that would help us. Thank you.
Posted by: alethea | May 12, 2008 2:37:06 PM
How far is Planet Earth & Our Solar System from the Dense Disc of the Milky Way Galaxy? I can't get this answer from anyone at NASA or Jet Propulsion Laboratories either! Why are they quiet about this data? I am told Planets passing through this Disc do not make it without massive loss of Life! I have read we are within 48 months of reaching the horizontal plane of Our Galaxy! Is this true? Please, e-mail me your findings on this Life & Death issue. Thank you, Ron
Posted by: Ron Gauvin | May 14, 2008 3:11:51 PM
Ron Gauvin
We pass through a sparse area of a spiral arm "every 35 to 40 million years increasing the chances of a comet collision tenfold."
However, this is not akin to the KT event or the PT event which were really bad circumstances so don't let it worry you.
Posted by: Quietman | May 14, 2008 4:05:56 PM
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