
Meteorites pummel the Moon far more than expected - Mz
http://www.nature.com/news/meteorites-pummel-the-moon-far-more-than-expected-1.20777
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ChuckMcM
I found this a very interesting paper. But given, 722 impacts over 7 years
with a median sized 25 meter diameter crater, that is about 490 m^2 getting
hit every 11 days. If such impacts were perfectly randomly distributed that is
like 20K years before you have hit everywhere on the planet. You still have a
much better shot at getting hit by an natural disaster that destroys your
Earth base than this.

That said, it does mean you should keep watch for incoming impacts. Even a
couple of kilograms of Chondrite coming in at 27,000 miles an hour is going to
leave a mark on your fancy moon base. Subterranean safe rooms and auto sealing
atmosphere preservation doors are going to be required equipment.

~~~
Patrick_Devine
Given that the moon is tidally locked to the Earth, all you need to do is put
the base on the near side of the moon and you'll dramatically reduce the
chance of being hit by a meteor.

Compare the far side [1] to the near side [2].

[1]
[https://en.wikipedia.org/wiki/Far_side_of_the_Moon#/media/Fi...](https://en.wikipedia.org/wiki/Far_side_of_the_Moon#/media/File:Back_side_of_the_Moon_AS16-3021.jpg)
[2]
[https://en.wikipedia.org/wiki/Near_side_of_the_Moon#/media/F...](https://en.wikipedia.org/wiki/Near_side_of_the_Moon#/media/File:Moon_nearside_LRO.jpg)

~~~
ars
> dramatically reduce the chance of being hit by a meteor.

As seen from the moon the Earth is only 2 degrees across - that leaves the
other 178 degrees wide open for hits.

I doubt it makes much difference to the hit rate - and certainly not
"dramatically reduce".

~~~
cnlevy
Even though earth's direct shielding is only 2 degrees, its gravitational pull
will deflect meteorites coming towards the moon from a far wider angle

~~~
ars
I thought of that, but Earth's gravitation pull will also deflect meteors
toward the Moon.

Averaged over the entire sky it's a null effect.

~~~
astrobe_
Is the distribution truly random as the article states? For instance, aren't
the poles bit more safe?

~~~
ars
Mostly random. The poles would have less direct hits, but equal number of
sideways hits. Mainly because I think most meteors orbit in the same plane as
the solar system. So there would be less "from above" hits on the poles.

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ghshephard
_" Meteorites have punched at least 222 impact craters into the Moon's surface
in the past 7 years. That’s 33% more than researchers expected..."_

It's unclear from the article whether they are saying that they _observed_ 222
impact craters, or _calculated_ that there were 222 impact craters across the
moons surface.

222 impact craters across the entire moon over 7 years, is an insignificant
number.

~~~
intortus
It's not unclear at all.

> Speyerer’s team used a computer program to automatically analyse 14,092 of
> these paired images, looking for changes between the two. The 222 newfound
> craters are distributed randomly across the lunar surface, and range between
> 2 and 43 metres in diameter.

~~~
ghshephard
I read that paragraph a dozen times before writing my comment. Still not 100%
certain that the analysis _saw_ the newfound craters, or calculated that they
existed based on visual data (such as splotches). I'm leaning 80/20 to the
fact that they visually identified the 222 craters, but I wouldn't give 20:1
odds on it.

~~~
intortus
What's the difference between _seeing_ and "calculating based on visual data"?
If you're looking for live observations of impacts as they happened, this
paragraph makes it pretty clear that they're counting "splotches."

~~~
ghshephard
"Seeing" \- You physically see the crater on the moon.

"Calculating" \- you don't actually see all of the craters, but you can infer,
based on various new deposits/splotches of ejecta, that in the time reviewed,
that approximately 222 new craters were created on the surface of the moon.

The difference between the two, is that in the case of seeing 222 craters, it
leaves open the possibly that many others, particularly on the "Dark Side"
also occurred. In the case of calculating, it may be the case that they are
suggesting that a total of 222 major craters were created during that window
of time.

