A Meteoroid Hits the Moon

[Jamie]

June 13, 2006: There's a new crater on the Moon. It's about 14 meters wide, 3 meters deep and precisely one month, eleven days old.

NASA astronomers watched it form: "On May 2, 2006, a meteoroid hit the Moon's Sea of Clouds (Mare Nubium) with 17 billion joules of kinetic energy—that's about the same as 4 tons of TNT," says Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL. "The impact created a bright fireball which we video-recorded using a 10-inch telescope."

Lunar impacts have been seen before--"stuff hits the Moon all the time," notes Cooke--but this is the best-ever recording of an explosion in progress:

video-recorded by MSFC engineers Heather McNamara and Danielle Moser.

The video plays in 7x slow motion; otherwise the explosion would be nearly invisible to the human eye. "The duration of the fireball was only four-tenths of a second," says Cooke. "A student member of our team, Nick Hollon of Villanova University, spotted the flash."

Taking into account the duration of the flash and its brightness (7th magnitude), Cooke was able to estimate the energy of impact, the dimensions of the crater, and the size and speed of the meteoroid. "It was a space rock about 10 inches (25 cm) wide traveling 85,000 mph (38 km/s)," he says.

If a rock like that hit Earth, it would never reach the ground. "Earth's atmosphere protects us," Cooke explains. "A 10-inch meteoroid would disintegrate in mid-air, making a spectacular fireball in the sky but no crater." The Moon is different. Having no atmosphere, it is totally exposed to meteoroids. Even small ones can cause spectacular explosions, spraying debris far and wide.

According to the Vision for Space Exploration, NASA is sending astronauts back to the Moon. Are these meteoroids going to cause a problem?

"That's what we're trying to find out," says Cooke. "No one knows exactly how many meteoroids hit the Moon every day. By monitoring the flashes, we can learn how often and how hard the Moon gets hit."

The work is underway. Using a computerized telescope built by Rob Suggs and Wesley Swift of the Marshall Space Flight Center, Cooke's group is monitoring the night side of the Moon "as often as ten times a month, whenever the lunar phase is between 15% and 50%."

http://science.nasa.gov/headlines/y2006/13jun_lunarsporadic.htm

[Jamie]

IMPACT MOON: In only 30 hours of observing, astronomers at the Marshall Space Flight Center have recently photographed seven explosions of light on the Moon. Each one, they believe, was caused by a meteoroid falling from the sky and hitting the ground.

The flashes seen by the Marshall group ranged in brightness from 7th to 9th magnitude, which means they were invisible to the human eye, but easy targets for backyard telescopes. Amateur astronomers are thus invited to join the hunt.

[AstroTiger]

one thing i have come to realise is that the moon is not the dead world everyone seems to think it is. A good astronomer friend of mine said that you never get the same view of the mean for another 18 years.

A facincating subject that i think is often neglected and overlooked IMHO

Al