Giant Hypothetical Ice Meteor

[sm625]

So lets say there's a giant meteor that enters the atmosphere and it is made of only water ice. :biggrin:

Assume that it completely melts in the atmosphere and doesnt crash into the ground no matter how big it is.

How big around would it have to be to raise the sea level by 40ft? (Assume it melts and all falls as rain.)

 

[Ben90]

http://www.freerepublic.com/focus/f-chat/2431569/posts + the area with an elevation less than 40'.

 

[colonelciller]

back of napkin... ~5,000,000 cubic kilometers ice meter

 

[colonelciller]

to get ^#:

volume of greenland ice approximately known to be ~2,850,000 cubic kilometre
Total sea level rise after all of greenland ice melts (this will happen) --> 23.6'

note... volume rise to melted greenland ice does not include the sea level rise that will occur in addition to that due solely to the expansion of ocean water as it warms... the expansion will be small for any small unit volume, but there is a lot of water. Also, no way greenland ice melts without enormous meltage also occuring on antartica... so add another 100-200 feet meltage there. Anyway, the above 2 #'s from wikipedia are all you need to do a quick 2 minute estimate of how large your ice meteor needs to be.

 

[WHAMPOM]

So lets say there's a giant meteor that enters the atmosphere and it is made of only water ice. :biggrin:

Assume that it completely melts in the atmosphere and doesnt crash into the ground no matter how big it is.

How big around would it have to be to raise the sea level by 40ft? (Assume it melts and all falls as rain.)

Take 3/4's of the area of the Earth plus 10% and multiply by 40 feet. Now figure how many weeks this giant ice asteroid must orbit in atmosphere to melt?

 

[colonelciller]

ok, so I was curious what this ball of ice would look like and I made a quick little scale model in vector format... then I just went for it and created a not-so-little animated gif :biggrin:

 

[colonelciller]

once you've resized it for viewing right click to "view image"... otherwise it's just unwiedly big

 

[Agent11]

I think it's safe to say it would cause quite a bit of damage on impact if it were a solid object like that.

Could work if there were thousands of separate objects though, like if the Oort cloud was disturbed by a rogue planet.

 

[Doomer]

ok, so I was curious what this ball of ice would look like and I made a quick little scale model in vector format... then I just went for it and created a not-so-little animated gif :biggrin:

That's cool.

 

[Biftheunderstudy]

Giant ice meteors already have a name, comets. The impact of something that large would be rediculous.

Just some simple math.

Suppose the comet hits the earth at escape velocity (this is reasonable, if its pulled in by Earth's gravity), then just taking the above size as is (because I'm lazy). Then v ~ 68 km/s.

It's mass is rho*V ~ 10^18 kg.

The kinetic energy is ~ 10^28 Joules. Or about 10,000 times more energy than the impact that killed the dionosaurs.

In fact, this is probably enough to completely tear off a good chunk of the surface/mantle in an event similar to the one which formed the moon but on a smaller scale.

Either way, bad news, definitely extinction event.

 

[Arxinall]

Dang