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(meteorobs) From Benny Peiser's Web Site
(3) MYSTERY OF THE 1953 LUNAR FLASH
>From Pravda, 16 January 2003
http://english.pravda.ru/main/2003/01/16/42120.html
A mysterious flash on the Moon registered half a century ago still agitates
the minds of scientists. If the flash was the result of falling of a large
asteroid, it means that such collisions with the Moon and the Earth may
happen oftener than was earlier supposed.
In 1953, astronomer Leon Stuart took a picture of the Moon with a bright
spot in the center of its visible surface. The brightness of the flash
corresponded to the energy liberation equivalent to an explosion of about
500 kilotons.
Astronomer Bonnie Buratti from NASA's Jet Propulsion Laboratory (JPL) in
Pasadena says that the newly obtained data allow to suppose that the flash
on the Moon could be the result of falling of an asteroid of about 20 meters
in diameter. If she is right, it may mean that collision of asteroids with
the Moon (and with the Earth) may happen oftener: approximately once in 500
years with the Moon, and once in 30 years with the Earth.
The crater formed after falling of the hypothetical asteroid is too small to
be discerned from the Earth. However, astronomer Buratti says that the
pictures made from the Clementine automatic station on the circumlunar orbit
in 1994 revealed a new crater which appeared as a result of impact. The new
crater was exactly in the region where Leon Stuart discovered the flash 50
years ago. Ejection of a brighter substance cover the territory of 1.5
kilometers in diameter; and the color indicates that the crater is new
enough.
Nevertheless, several scientists still insist that the picture presented by
Stuart reveals not an asteroid falling on the Moon, but a so-called
stationary meteor, a rather rare phenomenon: the meteor's mechanical
trajectory is directed along the eyesight axis of an observer, so that the
observer can see only a flash in the sky.
Skeptics assume that the meteor on Stuart's picture just accidentally
projected on the picture of the Moon disk in the background. Despite the
fact that such stationary meteors are rarely observed, they still happen
oftener than falling of large asteroids on the Moon. Besides, opponents of
Bonnie Buratti say that existence of the "new" crater on the Moon is of
slightest importance: there are no effective criteria to determine its
actual age. It is likely that the "new" crater is 20 million years old and
it is just a bit newer than others.
Bonnie Buratti rejects such doubts. She says that Stuart was a very
experienced astronomer. His picture was taken with the exposure of half a
second; there were no signs of camera movement; and the flash itself
occurred in the Moon's part along its orbit, where fallings of meteorites
are highly possible. Bonnie Buratti says that discovery of the crater in the
pictures taken from Clementine proves that the astronomer was right when 50
years ago he took a picture of the Moon at the moment when a new crater
appeared on the planet.
Copyright 2003, Pravda
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