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Explosions on the Moon

moon impact map.jpgNASA has released a map of 100 explosions on the Moon, observed in just the last two and half years (news coverage). If you want to live up there, you’d better get a hard hat.

“They’re explosions caused by meteoroids hitting the Moon,” says Bill Cooke, head of NASA’s Meteoroid Environment Office at the Marshall Space Flight Center (press release). “A typical blast is about as powerful as a few hundred pounds of TNT and can be photographed easily using a backyard telescope.”

NASA started up its Moon explosion monitoring towards the end of 2005. As they were planning to send astronauts back there “it seemed like a good idea to measure how often the Moon was getting hit”, says Rob Suggs, also at the Marshall centre.

The NASA team found there is no time of year when impacts fall to zero. Meaning if, and it’s a big if, there is to be a space colony on the Moon, they’ll need some form of protection.

Meteoroids hit the Moon so fast, normally at least 13,000 m/s, that they heat up the surface enough that it glows. Hence you get an ‘explosion’ despite a lack of oxygen.

Video of an impact below the fold.


moon impact.gif

Image top: map of impacts Science@NASA

Video: Science@NASA

Comments

  1. Wade Whitlock said:

    Two comments.

    1. This obviously means that the Earth has not “cleared its orbit.” Therefore, the Earth is not a “planet”.

    2. What’s the surprise? Other than the fact that we now have optics capable of “seeing” the heat signature of a 13,000kps impact and are using them.

    Science Fiction writers have been dabbling with the problem for a long time.

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  2. Richard said:

    “Therefore, the Earth is not a “planet”." – where does the “therefore” come from?

    The Earth gets showered by meteorites regularly.

    1. 100 explosions in a period of 2 1/2 years over the surface of the moon means that the probability of getting hit by a meteor is very low.

    2. There seem to no explosions towards the poles where the settlement is likely to be. Making the probability even smaller.

  3. Nathan Myers said:

    The story’s one surprise was to make me realize that you could be killed by shrapnel from a small strike a thousand km away. If a fragment doesn’t get escape velocity, it will come down somewhere going just as fast as when it started, and as likely far away as nearby.

  4. Wade Whitlock said:

    Richard,

    I am being sarcastic. A group of astronomers recently voted to define a “planet” as, among other characteristics, “having cleared its orbit”. Earthobviously hasn’t and therefore has lost its status, as did Pluto.

  5. Richard said:

    If by “clearing its orbit” they meant not being hit by meteorites then every planet would fail the definition. Possibly Pluto, having such an elliptical orbit, could be in danger of colliding with an object of comparable size or even bigger (like Neptune?). That definition needs further clarification.

    Talking of which I object to Pluto being dethroned from its position as a planet. The astronomers have clearly been arbitrary in their definitions. It should have been put to vote on the internet.

    The moon colony would have to be underground anyway. To avoid other much more present dangers – those from cosmic rays, the cold, the vacuum. In doing so it would also avoid the much smaller danger of being hit by meteorites.

    The Chunnel digging machine would do nicely on the moon.

  6. Mike Maxwell said:

    So how big are these meteoroids? Given the energy released and the speed, it should be easy to calculate. And are there more hits during meteor showers? (The issue I’m getting at is the usual statement that the meteors we see during meteor showers are the size of a grain of sand. I’ve always been skeptical that a grain of sand, even at 10 or 15 kps, could make that large a trail in the Earth’s atmosphere.)