Asteroid Hitting Moon

Terraformer · 2007-11-17 08:15:14

Would it be more dangerous for a large asteroid to hit the moon as it might knok it off it's orbit (if the asteroids big enough) or blast part of it away, destroying the moon and causing havoc on Earth.

cIclops · 2007-11-17 11:45:53

No. There are no asteroids that large that cross the orbit of the Moon.

Terraformer · 2007-11-17 13:25:54

But what about a chance collision diverting one?

nickname · 2007-11-26 20:34:12

Terraformer,
Great question, one i have thought about before.

cIclops,

Maybe no real large asteroids heading towards the moon.
But what about comets that we know nothing about?
Could be one heading for the moon or earth right now, until it passes the orbit of Mars we won't see it.

A semi decent sized comet hitting the moon could be a colossal problem for Earth.
Picture the ejected material from the very high speed comet impact from the moon spread all around the orbit of the moon and earth.

Earth receives small impacts for years to hundreds of years.
A cloud of fine dust remains between Earth and the moon for much longer decreasing Earths light content. (long ice age)
Since the impact speed of a comet is so high the moon wont retain most of the ejected material, but the earth will slowly capture almost all of it as impactors.

We cheer as the Moon saves us from a earth shattering smack, a one in a million chance that our moon is in the right place at the right time to stop the comet from a direct collision with earth.
We are deeply saddened just a few short days later as the after effects start to show up and in retrospect are far worse than the direct earth collision would have been.

cIclops · 2007-11-27 02:09:31

It would be a far greater problem if the comet hit Earth. An impact with the Moon would vaporize most of it. Pieces of Moon and comet would be ejected and some would hit Earth, most would fall back onto the Moon or go into solar orbit. Only those with a specific range of velocities (about 3-10 km/s) would hit Earth. Very few would have the right velocity vector to travel directly to Earth. So most would take a long time to hit Earth, typically many thousands of years. The majority of the energy of the comet would be transfered to the Moon, only a part of the rest would affect Earth spread over a long time.

scale diagram of the Earth Moon system - note that comets are usually less than 50 km across.

nickname · 2007-11-27 05:31:41

cIclops,

The impacts on earth would be more of a nuisance than anything, maybe a few serious ones cause local panic and pretty bad damage.
Moon dust trapped in orbit on the other hand could be a serious problem for earthly light levels for extended periods.

If the comet had a head on collision with the moon things are not to bad, but a shallow glancing impact could kick up enough dust and debris to set earth into hundreds/thousands of years of ice age.
Just a drop of say 5% of light would do that.

The impact with Earth of such a fast object would be a serious event, but all the effects dissipating in less than 1 year.
Local disaster on a grand scale, after effects on Earth like a volcanic event for 1 year.

cIclops · 2007-11-27 07:51:58

How much of a 50km comet impacting the Moon would immediately reach Earth in a worst case?

Terraformer · 2007-11-27 09:11:15

I've just thought of something really cool. A comet slamming into the moon and the debris turning earth into a ringed planet.

nickname · 2007-11-28 05:28:29

cIclops,

All depends on the exact impact size/speed/angle.
I can't imagine an impact that many big pieces get to Earth other than a very shallow almost miss Moon sort of hit.

Even a direct thumping hit on the moon with a 50km comet would probably kick up enough dust and debris in all sorts of orbits to alter Earth sunlight for ages though.
Any of the debris from the impact on the moon that doesn't have big escape speeds will settle into sloppy long term orbits around earth.

Maybe 25% returns to the moon, 50% is high enough speed material to leave Earth/moon gravity totally, 1% makes it to earth pretty quick and the rest stays in sloppy Earth orbits.

I think with a comet as big as 50km we would want the moon to take the hit no matter what the outcome, 50km on Earth would be a global killer 100% chance.
A 1km or smaller comet and we might not want the moon to take the hit.

Terraformer,

That is the exact scenario i see for a decent sized impact with the moon.
Earth probably wouldn't need a second magnetic field produced from the dust and the lowered light levels.
Both of those could be very disturbing to all life on Earth.

Having a ring sure would be a pretty thing to look at though

nickname · 2007-11-28 05:42:03

cIclops,

This is a worse case scenario i can think of.

A semi large comet just misses earth and smacks directly into the moon face always pointing at Earth.

Most of the high speed ejected material now is directed towards Earth.
100s of decent sized impacts happen in short periods of time that cook Earths atmosphere.

A decent amount of the remaining material is stuck in between earth and moon in sloppy orbits.

The moon can be an enemy almost as easily as a friend

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#1 2007-11-17 08:15:14

Re: Asteroid Hitting Moon

#2 2007-11-17 11:45:53

Re: Asteroid Hitting Moon

#3 2007-11-17 13:25:54

Re: Asteroid Hitting Moon

#4 2007-11-26 20:34:12

Re: Asteroid Hitting Moon

#5 2007-11-27 02:09:31

Re: Asteroid Hitting Moon

#6 2007-11-27 05:31:41

Re: Asteroid Hitting Moon

#7 2007-11-27 07:51:58

Re: Asteroid Hitting Moon

#8 2007-11-27 09:11:15

Re: Asteroid Hitting Moon

#9 2007-11-28 05:28:29

Re: Asteroid Hitting Moon

#10 2007-11-28 05:42:03

Re: Asteroid Hitting Moon

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