This week we have a mystery from the 1950s which we may be able to help resolve.
An amateur astronomer from Oklahoma, Dr. Leon Stuart, photographed a bright flare on the surface of the Moon while tinkering with his new camera in November 1953. The flare or flash was close to the Moon’s terminator and near the centre of the Moon’s face (see following image) and lasted for approximately eight seconds. Dr. Stuart published his photograph and description of the sighting in The Strolling Astronomer newsletter in 1956. He remained convinced until the end of his life that he had seem an asteroid impact the Moon’s surface but most astronomers were skeptical and said that the flash was either a meteor burning up in the Earth’s atmosphere which just happened to appear as if it was an impact on the Moon, or it was a problem with the film in the camera.
Dr. Stuart logged the event as follows:
Made by Dr. Leon Stuart, Nov. 15, 1953 at 01:00 UT. Lasted 8 to 10 sec. Also observed visually. Star images rather steady, no extraneous lights. Exposure: 1/2 sec. on E.K. 103aF3 plate. 8 inch f/8 reflector.
Position on Lunar surface is about 10 miles S.E. of Pallas. (-0.5; +.08).
Photo from Dr. Leon Stuart
Within astronomy circles Dr. Stuart’s impact was known as Stuart’s Event and was mostly ignored until recently (2002) when two scientists took an interest in this 50-year old mystery. Dr. Bonnie J. Buratti, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California and Lane Johnson of Pomona College, Claremont, California, researched the event and their findings included some very persuasive evidence which indicated that Stuart’s photo was indeed real and is of immense historical value.
Stuart’s remarkable photograph of the collision gave us an excellent starting point in our search, we were able to estimate the energy produced by the collision. But we calculated that any crater resulting from the collision would have been too small to be seen by even the best Earth-based telescopes, so we looked elsewhere for proof. Using Stuart’s photograph of the lunar flash, we estimated the object that hit the Moon was approximately 20 meters (65.6 feet) across, and the resulting crater would be in the range of one to two kilometers (.62 to 1.24 miles) across. We were looking for fresh craters with a non-eroded appearance. [Dr. Bonnie Buratti]
The two scientists decided to search for the crater using images taken from spacecraft orbiting the Moon. They had no luck with images from the Lunar Orbiter in 1967 but they did find a likely candidate in the images returned by the Clementine 1994 mission. It was a 1.5km wide crater with a fresh-looking layer of material surrounding the crater and the size was consistent with the energy from the observed flash.
Photo Courtesy JPL, Dr. Bonnie Buratti, Lane Johnson
At this point it appears that the mystery has been solved but there are detractors who have found images of the Buratti/Lane crater in photos taken by two ground based telescopes before 1953, which rules out that crater as having been formed by Stuart’s Event. It was also ruled out by the editors of Sky and Telescope magazine who carefully measured the image of Stuart’s Event and determined that it was centred 30km from the Clementine candidate.
Maybe the Moon Zoo users can find this elusive crater if it exists! The following image shows the general area where the flash was seen. The final link under the “References” heading below contains coordinates of where the impact may have occurred.
Unfortunately, it appears that there is not complete coverage of the area by LRO – some areas do not have NAC images so the search will be difficult.
If you do find any candidates for Stuart’s Crater please post them in the Moon Zoo forum.
A good overview of the whole story with images of the event will be found here:
Stuart’s Event, Bright Flare, November 15, 1953
The following journal contains a re-publication of the original Strolling Astronomer article by Dr. Leon Stuart (page 21)
Journal of the Association of Lunar & Planetary Observers, Vol 45 Number 2
This strange link contains more images of Stuart’s Event and also coordinates of where the impact may have occurred. Scroll down within the page and it has maps of the lunar surface with the area where the impact is suspected to have occurred highlighted.
1956 Lunar Path Light?