Asteroid threat in 2032? Don't panic, but don't brush it off

Five monks from Canterbury reported to the abbey's chronicler, Gervase, that shortly after sunset on June 18, 1178, (25 June on the proleptic Gregorian calendar) they saw "the upper horn [of the moon] split in two". Furthermore, Gervase writes:

From the midpoint of the division a flaming torch sprang up, spewing out, over a considerable distance, fire, hot coals and sparks. Meanwhile the body of the Moon which was below writhed, as it were in anxiety, and to put it in the words of those who reported it to me and saw it with their own eyes, the Moon throbbed like a wounded snake. Afterwards it resumed its proper state. This phenomenon was repeated a dozen times or more, the flame assuming various twisting shapes at random and then returning to normal. Then, after these transformations, the Moon from horn to horn, that is along its whole length, took on a blackish appearance.

Interesting.

I certainly did not intend to offend. Thanks for the tip on some astronomical history.

I did find your suggestion that all of the cratering of the moon was done in its early days (before man) a bit off putting. This bit of history certainly would suggest that it is not entirely true.

Oh and I guess I should have said “written history” instead of recorded history.

Although Neanderthal cave paintings do some convey information as to their view of their world I would not consider cave paintings a ‘record’ because no specific event can be discerned from the painting. You may say that here there was a bison hunt but you can not discern which bison hunt or who was leading the hunt or where that hunt occurred.

For me to consider something a historical record it needs at least who did what where and when.

To put it to bed, if there were something big enough to impact the Moon, something on the order of the pieces of the comet that hit Jupiter, what isn’t blown away and into deep space from the gravitational pull of the Earth is going to come crashing into us. It’s a darn good thing Jupiter is a gas giant. If it were a terrestrial planet enough big impacts over time and it too would be obliterated.

Shoemaker-Levy 9 in 1994 was on a collision course with Earth, if Jupiter had not been in the way? I’ve not seen that stated anywhere. Do you have a (reputable) link?

Googling this, I found a couple (rather shaky) sources indicating that a collision with Earth was possible somewhere down the line, but those were initial calculations and were revised once Shoemaker-Levy 9’s orbit was better known. Granted, who would take Jupiter out of the equation?

I’d also clarify: MOST of the cratering of the Moon, as Earth’s, occurred in it’s early days, but not all of it. However, it is probably correct to say that the Earth protects the Moon more than the Moon protects the Earth (until we build an asteroid defense station on the Moon, anyway!)

The info on Shoemaker 9 I saw on The Science Channel, if they’re correct in what they said. What sources were you looking at? Face it, without big brother Jupiter out there it’s likely we wouldn’t be here. However the Big Guy can’t catch them all and one day it’s going to be POW!, Goodnight Irene! If the cratering of the Moon didn’t all occur in it’s formation then when did the rest of it? And when has the Moon ever acted as a cosmic shortstop, I’m curious to know? Mercury shows evidence of heavy bombardment as well as Jupiter’s moons Ganymede and Callisto. Because Europa’s surface, if not the entire moon itself is one big ice ball, it’s surface shows less evidence of cratering but only because the surface keeps freezing and then cracking apart.

I researched further: Shoemaker–Levy 9 had been orbiting Jupiter for 20-30 years before it was discovered.

http://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9

Prior to that, it was most likely orbiting (basically) between Mars and Jupiter:

Benner, L.A.; McKinnon, W. B. (March 1994). “Pre-Impact Orbital Evolution of P/Shoemaker–Levy 9”. Abstracts of the 25th Lunar and Planetary Science Conference, held in Houston, TX, March 14–18, 1994 25: 93.
(Reference 8 in the Wikipedia article.)
http://adsabs.harvard.edu/abs/1994LPI....25...93B

Also see references 39 and 40 regarding Jupiter's role as a “cosmic vacuum cleaner” (it's unclear, as Jupiter seems to help with regard to asteroids but may make comet impacts with Earth more numerous.)

The Science Channel gets lots of things wrong...

It is also worth noting that perturbations from Jupiter are the main reason the mass of the asteroids did not accrete into a larger body, but instead was broken up into smaller bodies, some of which end up coming our way.

Now as for the cratering of the Moon, MOST of it occurred over 2 billion years ago, but impacts have most certainly continued at a slower pace, as they have on Earth. For example, Tycho (a truly spectacular crater) is believed to be only about 108 million years old.

http://en.wikipedia.org/wiki/Tycho_(crater)

and

http://www.imageagain.com/Strata/StratigraphyCraters.2.0.htm

Last, where did I say the Moon had acted as a cosmic shortstop? It's gravity well is clearly not big enough to do so consistently. That weak gravity is in fact a major reason why (eventually) it would be a good place to launch an asteroid interceptor or interceptors from.

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