Moon Blast

New Evidence Supports Moon Blast

{Something to inspire us all .....}

The New York Times
March 4, 2003
A Flash From the Past: New Evidence Supports Moon Blast
By HENRY FOUNTAIN

Humans have gazed at the Moon in wonder since ancient times, but what Dr.
Leon Stuart observed one night in 1953 was more wonderful than what anyone
had seen before or since.

Looking through his eight-inch telescope at his home near Tulsa, Okla., Dr.
Stuart, a radiologist by profession but an astronomer by avocation, saw and
photographed a bright flash on the Moon's surface.

Dr. Stuart was certain that he had witnessed a small asteroid hitting the
Moon, the flash being the fireball from the event. An amateur astronomy
journal published his photograph and report, and it has remained a
curiosity over the years. While some scientists thought his explanation
plausible, others were convinced that he saw an optical aberration or a
much closer object, like a meteorite in Earth's atmosphere (or,
embarrassingly, an airplane passing overhead).

Now new research shows that Dr. Stuart's flash on the Moon was no flash in
the pan. An astronomer at NASA's Jet Propulsion Laboratory, poring over
high-resolution lunar photographs, has found a fresh crater in the precise
area where Dr. Stuart saw his flash.

"I think it's a very good candidate," Dr. Bonnie J. Buratti, an astronomer,
said of the crater, which is about 250 to 800 yards in diameter. Dr.
Buratti worked on the project with Lane Johnson, then a student at Pomona
College; the two have published their findings in latest issue of the
astronomical journal Icarus.

At the Jet Propulsion Laboratory, Dr. Buratti served on the science team
for the Clementine spacecraft, which thoroughly photographed the Moon in
1994. As part of that work, she and others had looked for evidence of
transient phenomena like asteroid impacts and had found none. Just as they
were preparing a paper on their research, a colleague mentioned what is
known as Stuart's event.

"I had never heard of it," Dr. Buratti said. But her curiosity was piqued,
so she found a 1953 copy of the amateur journal The Strolling Astronomer
and looked at the photo.

She and Mr. Johnson were able to determine the approximate location of the
flash, a circular area with a radius of about 20 miles. From the brightness
of the event, they estimated the force of the impact to be about half a
megaton, equal to a small hydrogen bomb. Their best guess as to the size of
a feature created by such an impact, including a crater and its ejecta
blanket, the material thrown out around the sides, was 1.2 miles or less ?
too small to see from ground-based photographs.

So first they looked at photographs taken by the lunar orbiters in the
1960's, which mapped areas of the Moon to prepare for the Apollo landings.
These photos were inconclusive, so they turned to the huge database of two
million images from Clementine. Many of these photographs were taken with
color filters, which can help in determining the age of a surface feature.

On the Moon, material that is freshly exposed has a slight bluish tinge.
Over time, because of the constant bombardment of cosmic rays, other
high-energy particles and micrometeorites, the structure of the material
changes and iron particles tend to predominate, making the material
slightly red.

In the Clementine photos, Dr. Buratti and Mr. Johnson found one small
crater that was "very, very blue and fresh appearing," Dr. Buratti said. It
also happened to be in the exact center of the area they were looking. And
it was the proper size ? slightly less than a mile across, including the
ejecta blanket. Dr. Buratti estimated the size of the asteroid at 20 yards
in diameter.

She said that although there was a good deal of uncertainty in their study,
she was "about 90 percent" confident that the crater was the one created by
the fireball Dr. Stuart observed. "There's no other object that stands out
as a candidate," she said.

Dr. Stuart, who died in the 1960's, was not one to make wild claims. "He
was very careful to eliminate all the other possibilities," she said. "At
the time, scientists didn't even agree that craters were caused by impacts.
So he was very conservative."

If Dr. Stuart observed an asteroid impact, he saw something that was
extremely rare: a rock of that size hits the Moon only once or twice a
century, according to best estimates.

But Dr. Buratti said she wasn't surprised there was a witness. "I would
contend that at any given time, some amateur or professional astronomer is
watching the Moon," she said. "With a blast of this sort, someone would be
likely to see it."

Copyright 2003 The New York Times Company

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