Posted on 05/21/2008 2:11:19 PM PDT by blam
100 Explosions on the Moon
A map of the 100 explosions observed since late 2005.
Not so long ago, anyone claiming to see flashes of light on the Moon would be viewed with deep suspicion by professional astronomers. Such reports were filed under "L" ... for lunatic.
Not anymore. Over the past two and a half years, NASA astronomers have observed the Moon flashing at them not just once but one hundred times.
"They're explosions caused by meteoroids hitting the Moon," explains Bill Cooke, head of NASA's Meteoroid Environment Office at the Marshall Space Flight Center (MSFC). "A typical blast is about as powerful as a few hundred pounds of TNT and can be photographed easily using a backyard telescope."
As an example, he offers this video of an impact near crater Gauss on January 4, 2008.
The impactor was a tiny fragment of extinct comet 2003 EH1. Every year in early January, the Earth-Moon system passes through a stream of debris from that comet, producing the well-known Quadrantid meteor shower. Here on Earth, Quadrantids disintegrate as flashes of light in the atmosphere; on the airless Moon they hit the ground and explode.
"We started our monitoring program in late 2005 after NASA announced plans to return astronauts to the Moon," says team leader Rob Suggs of the MSFC. If people were going to be walking around up there, "it seemed like a good idea to measure how often the Moon was getting hit."
"Almost immediately, we detected a flash."
That first detection—"I'll never forget it," he says--came on Nov. 7, 2005, when a piece of Comet Encke about the size of a baseball hit Mare Imbrium. The resulting explosion produced a 7th magnitude flash, too dim for the naked eye but an easy target for the team's 10-inch telescope.
A common question, says Cooke, is "how can something explode on the Moon? There's no oxygen up there."
These explosions don't require oxygen or combustion. Meteoroids hit the moon with tremendous kinetic energy, traveling 30,000 mph or faster. "At that speed, even a pebble can blast a crater several feet wide. The impact heats up rocks and soil on the lunar surface hot enough to glow like molten lava--hence the flash."
During meteor showers such as the Quadrantids or Perseids, when the Moon passes through dense streams of cometary debris, the rate of lunar flashes can go as high as one per hour. Impacts subside when the Moon exits the stream, but curiously the rate never goes to zero.
"Even when no meteor shower is active, we still see flashes," says Cooke.
These "off-shower" impacts come from a vast swarm of natural space junk littering the inner solar system. Bits of stray comet dust and chips off old asteroids pepper the Moon in small but ultimately significant numbers. Earth gets hit, too, which is why on any given night you can stand under a dark sky and see a few meteors per hour glide overhead—no meteor shower required. Over the course of a year, these random or "sporadic" impacts outnumber impacts from organized meteor showers by a ratio of approximately 2:1.
"That's an important finding," says Suggs. "It means there's no time of year when the Moon is impact-free."
Fortunately, says Cooke, astronauts are in little danger. "The odds of a direct hit are negligible. If, however, we start building big lunar outposts with lots of surface area, we'll have to carefully consider these statistics and bear in mind the odds of a structure getting hit."
Secondary impacts are the greater concern. When meteoroids strike the Moon, debris goes flying in all directions. A single meteoroid produces a spray consisting of thousands of "secondary" particles all traveling at bullet-like velocities. This could be a problem because, while the odds of a direct hit are low, the odds of a secondary hit may be significantly greater. "Secondary particles smaller than a millimeter could pierce a spacesuit," notes Cooke.
At present, no one knows how far and wide secondary particles travel. To get a handle on the problem, Cooke, Suggs and colleagues are shooting artificial meteoroids at simulated moon dust and measuring the spray. This work is being done at the Vertical Gun Range at NASA's Ames Research Center in Mountain View, CA.
Meanwhile, back at the observatory, the team has upgraded their original 10-inch (25 cm) telescope to a pair of telescopes, one 14-inch (36 cm) and one 20-inch (51 cm), located at the Marshall Space Flight Center in Alabama. They've also established a new observing site in Georgia with a 14-inch telescope. Multiple telescopes allow double- and triple-checking of faint flashes and improve the statistical underpinnings of the survey.
"The Moon is still flashing," says Suggs. Indeed, during the writing of this story, three more impacts were detected.
Very good....Thanks.
Astronomers and philosophers have, from time almost immemorial until very recently, asserted that the moon was uninhabited, that it had no atmosphere etc.. But recent discoveries, through the means of powerful telescopes, have given scientists a doubt or two upon the old theory.
Nearly all the great discoveries of men in the last half-century have, in one way or another, either directly or indirectly, contributed to prove Joseph Smith to be a Prophet.
As far back as 1837, I know that he said the moon was inhabited by men and women the same as this earth, and that they lived to a greater age than we do -- that they live generally to near the age of a 1000 years.
He described the men as averaging near six feet in height, and dressing quite uniformly in something near the Quaker style.
Oliver B Huntington 1892
Very good answer!
Have you ever been to KIRKWOOD, MO?
They have a very nice example of a preserved railway station on the Amtrak line.
My home was built by John KIRKWOOD
You have saved me having to type that!
A Meteoroid Hits the Moon
NASA | 6/13/2006
Posted on 06/14/2006 6:37:50 AM PDT by steve-b
http://www.freerepublic.com/focus/f-news/1649147/posts
Geminid Meteors Seen Striking The Moon
New Scientist | 1-5-2006 | Kelly Young
Posted on 01/05/2007 12:31:14 PM PST by blam
http://www.freerepublic.com/focus/f-news/1763035/posts
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Ping.
Thanks for the moon ping ping.
This is an indication of how much space debris hits the earth every day, and probably why the surface of the earth has built up over time (the older a layer of rock, the deeper it is buried).
He who smelt it, dealt it.
Not totally clear why this has only become apparent *since* 2005 - it’s not as if the moon is some obscure object that no one bothered to look at before. What kind of instrumentation is needed to see and catalog these flashes? Backyard telescope and a camera? Hubble telescope? Something in between?
Also wonder what, if anything, could be learned from the distribution of these flashes? Are they truly random, or are they biased in some way or another? If so what does that say?
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