Nasa image of the day 20/5

[Jamie]

2007 May 20

A Spherule from the Earth's Moon

Credit: Timothy Culler (UCB) et al., Apollo 11 Crew, NASA

How did this spherule come to be on the Moon? When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads. Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions. Pictured above is one such glass spherule that measures only a quarter of a millimeter across. This spherule is particularly interesting because it has been victim to an even smaller impact. A miniature crater is visible on the upper left, surrounded by a fragmented area caused by the shockwaves of the small impact. By dating many of these impacts, astronomers can estimate the history of cratering on our Moon.

[John]

Fascinating image Jamie, thanks for posting it.

They have found similar sperules (a little larger than these) around Meteor Crater in Arizona, USA. These are known as Nininger Spheroids after the Dr Harvey Nininger who first identified them and linked them to the formation of the crater.

John

[Black Shuck]

Incredible!! 8)

As John says - Fascinating!!

Bill

[barkis]

Incredible detail in such a small piece of material. I would guess scientists in this field would have been able to calculate the mass of the smaller impacter too, and It's velocity no doubt. When I first glimpsed the image Jamie, I thought immediately it was a radar image perhaps of Venus.

Ron.

[Kaptain Klevtsov]

By dating many of these impacts, astronomers can estimate the history of cratering on our Moon.

I've had some impacts caused by dating, but that's a different thing.

How would you go about dating the impacts I wonder? (No seriously this time )

Captain Chaos

[John]

How would you go about dating the impacts I wonder? (No seriously this time )

I think they can measure the extent to which material has been exposed to cosmic rays, ie: been on the surface of the moon rather than under it. From that they can work out when material was "excavated" by an impact.

With the few meteorites that have been proved to be of lunar orgin scientists can measure when they were formed (crystalised), how long ago they were blasted off the moon, how long they have been in space and how long they have sat on the earths surface before being found. This is not exact as yet but to within 5%-10% accuracy I understand. Clever stuff

John