Are Gravity Disturbances on the Dark Side Of The Moon Clues of a "Giant Impact"?

It sounds like a Buck Rogers plot, or a rave remix of Pink Floyd, but it's the very latest news from our very nearest astronomical neighbor.  The Japanese SELENE mission (SELenological and ENgineering Explorer) has probed the far side of the moon in unprecedented detail.  The effects will be felt in lunar research for years, but the first headline we'll hear about is the negative gravity disturbance rings.

Now that definitely sounds like something Electra, Queen of the Lunar Amazon Women, would apply to Buck before being seduced.  It's important not to get overexcited - here "negative anomaly" simply means that there's less gravity than average, not that there are anti-gravity sites hidden where we couldn't see them until now.  These rings surround small zones of positive gravity anomalies, unlike anything we've seen on the near side, and offer brand new information on the formation of the moon.

It seems that the two sides of the moon have evolved differently since their formation, with the far side forming at cooler temperatures and remaining stiffer while the Earth side has been modified at higher temperatures and for longer.  This information is extremely important for theories on the formation of the moon, of which the current favorite is the "Giant Impact" hypothesis aka "If Michael Bay and Joel Schumacher were hired to co-direct God."

The Giant Impact idea is that four and a half billion years ago a planet the size of Mars rammed Earth, kicking enough debris into orbit to accrete into an entirely new body, Mr Moon.  You'd think something like that would leave evidence more visible than gravitational mapping of the dark side of a satellite, but don't worry: we'll get there.

Luke McKinney.

Science, reference 10.1126/science.1170655

Comments

[Rev. Carl Bowers]

Nice article; but why illustrate it with that Photoshopped image? I've received it in e-mails from people, with comments that amount to "Wow, look at this amazing shot of the moon above the sun at sunset at the North Pole." People think it's real, in contravention of the dynamics of the Earth-Moon system. Putting it atop a straight science article adds credence to it as real, rather than a digital fauxto. See http://www.snopes.com/photos/natural/northpole.asp.

[TNT2073]

You have stupid friends, if they thought that was a real picture.

[Harrrie]

Why does TNT have to ruin the site with attacks on someone's friends? Does TNT know everything? NOOOO. So he must be stupid. Have some respect man.

[Danp52]

Luke do you have a crush on Micheal Bay? You consistently mention him in your articles.

[claudio]

It makes a lot of sense what they say about the far side of the moon being cooler and having cooled in the old days at slower rate than the nearside.

It is a matter of sun energy and its influence on planets and moons.

Regards