New Crater Revives Moon Mystery
A mysterious flash on the Moon caught on camera 50 years ago is still
provoking disagreements about its origin. Astronomer Bonnie Buratti says
her new results show that the flash was caused by a 20-metre asteroid
hitting the Moon.
15 November 1953: was this an asteroid hitting the Moon?
If Buratti is right, such impacts may be more frequent than thought -
about once every 30 years on the Earth, and every 500 years on the Moon.
But other asteroid watchers think the flash was due to a small meteor
burning up in Earth's atmosphere.
Amateur astronomer Leon Stuart's 1953 photograph of the Moon shows a light
spot near the centre of the Moon's visible surface. It would take a
half-megaton explosion to produce such a flash, says Buratti, of NASA's
Jet Propulsion Laboratory at Pasadena.
The resulting crater would not be visible from Earth, but it should appear
on close-ups taken by lunar probes. In a future issue of the journal
Icarus, Buratti reports a fresh impact scar at the site of the 1953 flash
on images collected by the Clementine spacecraft as it orbited the Moon in
1994. A bright blanket of ejected material covers an area that is about
1.5 kilometres across, and the colour of the debris indicates that the
crater is relatively new.