Wednesday, 21 January 2009

The end of the world

Prompted by Protege's post about a rare video capturing a meteorite striking the earth's surface and a request in the comments, here's a video I first saw a few months ago - it's a simulation of a massive asteroid colliding with the earth and the somewhat catastrophic after effects. I'm not sure where the simulation originates from, I think it might be from a show on the Discovery channel. Bear in mind that in the video Protege posted the meteorite was probably pebble sized and certainly not very large at all.

I have one or two issues with the simulation and not being a massive impact expert I certainly can't vouch for its accuracy. For instance, I have no idea why the asteroid appears to be glowing red before it collides, I think that's just some artistic license to make things look a little more dramatic. The likelihood of the planet colliding with a 500-km diameter asteroid is also extraordinarily unlikely, that's the sort of thing that happened during the formation of the solar system but is just so unlikely now it can be ruled out. The simulation ends with a claim that impacts such as these have occurred six times in the earth's history, but I suspect they really mean six extinction events, not six collisions with 500-km asteroids.

Having said that, you don't need such a big asteroid to destroy life on our planet. There's an interesting site that lets you input variables (with some hints) and calculates the results of possible impacts. In any case, collisions will occur again, and even ones with small asteroids, or comets, might cause some considerable inconvenience. It's why the study of asteroids is actually very important - firstly we find the ones that have the potential to collide with the planet and secondly we will learn how to deal with the threat - can we blow up an asteroid on a collision course, divert it or simply start praying?

For those that suffer nightmares or other unfortunate effects from watching apocalyptic videos, don't watch but just listen to the music! It's "The Great Gig in the Sky" by Pink Floyd - one of my favourite songs of all time and a good choice by the editors given the nature of the song.


Anonymous said...

You think you can dial an asteroid in on my dentists office?

Zuzana said...

Wow Tom, this is amazing; in a ominous kind of way.;)) A scary show for the eyes and soul.;)
Thank you so much for posting it and for linking to me.;))
By the way, I am very fascinated by the moon. Isn't there a theory that the moon is a product of a collision between and asteroid and the earth? What is your take on it?

Tom said...

Protege - there are a three main theories about the moon's formation. 1) it formed in situ with the earth, 2) it was captured by the earth's gravitional field and 3) it was caused by a collision between the earth and something else very early in the solar system's life.

The latter is by far my favourite as it fits the evidence. If the moon formed with the earth then the rocks would be identical. They're very close, but the moon lacks volatile elements/isotopes we see in earth rocks. Number 2 could happen, but statistically very unlikely. Number 3 explains many facts. The rocks are similar to earth's and the volatile stuff was burned off during the energetic collision (including water). Several groups have shown using physics-based computer models that the result of an earth-moon system from a collision is quite likely.

Incidentally, the collision was with something a little bigger than an asteroid - try a mars-sized planet! That sort of thing happened when the solar system was being formed. Fortunately it doesn't happen quite so often 4.5 billion years on...

Zuzana said...

Tom, thank you so much for the explanation; wow, size of Mars? Did the asteroid completely disintegrated upon impact then? Melted with the Earth, I take it.
This is all very fascinating.;)