Skip to comments.Moon's Youngest Crater Discovered
Posted on 12/19/2002 7:42:01 PM PST by blam
Friday, 20 December, 2002, 01:57 GMT
Moon's youngest crater discovered
Is this the youngest crater on the Moon?
By Dr David Whitehouse BBC News Online science editor
Astronomers have discovered the only known lunar crater to have been formed in recorded history. In 1953 a flash was seen on the Moon that was taken to be the impact of a small asteroid. But ground-based telescopes were not powerful enough to see any crater.
But now, searching more detailed images of the Moon obtained by orbiting spacecraft, researchers have found a small, fresh, crater in the same position as the flash.
It is believed that new small craters are formed on the Moon every few decades, but this is the first one to have been found.
Bright, blue and fresh
Leon Stuart's photograph. The flash is just off-centre
The 1953 photograph of a flash on the Moon by Leon Stuart, an American amateur astronomer, is the only definite evidence of an asteroid-sized body onto the lunar surface.
In 1178 Gervase of Canterbury reported seeing a bright flash on the Moon and some researchers believe that a crater called Bruno on the far side was the result, but doubt has been cast on that belief.
Dr Bonnie Buratti of Nasa's Jet Propulsion Laboratory in California and Dr Lane Johnson of Pomona College, California, looked at Leon Stuart's photograph and estimated that the object that struck the Moon was about 300 metres across and that its impact would have resulted in a crater 1-2 km in size.
They estimate that the energy released in the impact would be the equivalent of half a Megaton of TNT, or about 35 times more powerful than the Hiroshima bomb.
If it had struck the Earth such an impact would have caused the destruction of a large metropolitan-sized area.
Because such a small crater would not be detectable with Earth-based telescopes the astronomers examined images taken by spacecraft orbiting the Moon.
Bright, blue and fresh looking
A search of images from the 1994 Clementine mission revealed a 2-km crater with a bright, blue, fresh-appearing blanket of lunar sub-soil splashed around it at the exact location of the 1953 flash.
"Our candidate crater is in the right place, its size is consistent with the energy produced by the observed flash, it has the right colour and reflectance, and it's the right shape," Dr Buratti told BBC News Online.
Finding the new crater offers scientists the opportunity to study subsurface unaltered lunar soils before exposure changes them.
The research will be detailed in a forthcoming issue of Icarus, the journal of Solar System studies.
Multiple witnesses, fresh crater where they described the impact. They reported a phenomenon that conflicted with everything they knew about the perfection on the heavens. No reason to lie, and every reason to reject what they saw. What's to doubt?
There is a point on the mass scale, probably less than even this size, where the atmosphere can't slow the object appreciably, nor heat it so it fragments or explodes during the short time the object is inside the atmosphere. The result would be about the same on the earth or on the moon for the big meteorites.
[two years later] The doubt was cast by someone doing his doctoral work; he claims that, if there had been such an impact (the impact crater was identified a while ago), there should have been massive numbers of shooting stars reported. IOW, to take this criticism seriously, one has to assume that this lone researcher was able, in a matter of weeks or months, to comb through all medieval manuscripts (reading them in the original language); also, one has to assume that his assertion is correct -- which means he figured out, based on a brief account from 800+ years ago, the exact velocity and character of the impactor.
IMHO, the doubter is full of it.
Yeah... we just all go to work in the dark and come home in the dark for the next 500 years.