Saturday, 6 November 2010

Fire And Life From The Heavens

The subject of this weeks very interesting Horizon was asteroids and the influence they have had on this planet throughout it's history.  Now if you believe Hollywood, and the majority of received popular science asteroids are out there to get us and have already polished off a large number of species that have attempted to make this planet there home. Well it turns out that this is true for the most part.

I was under the impression that we have a pretty good idea of where these are and more importantly where they are going. Unfortunately this appears not to be true, yes we have identified all the really big ones, ones capable of wiping out a continent or worse. These however are really rare and apparently it's the small ones we need to be worrying about. The latest research suggests an asteroid a mere 30m across exploding in the lower atmosphere would have the same effect on a city as a nuclear bomb many times more powerful than the Hiroshima Bomb. There are a lot of asteroids about 30m across.

So we would really like to know where these things are, unfortunately they are so small we will probably get about twenty-four hours notice if one gets too close. That's a day to evacuate an entire city? A day to make sure nobody gets the wrong idea and triggers a full scale nuclear war when a city disappears as if hit by the Bomb. Scared yet? Apparently last year Barak Obama was alerted was when an asteroid was spotted and calculated to hit the earth in less than a day. The asteroid exploded in the upper atmosphere over the Bolivian desert but produced an explosion easily visible from space. Not much we can do, but at least somebody is looking!

It turns out however that asteroids are not just harbingers of doom. They may have played a part in the creation of life itself. Current thinking is that a large proportion of the water that swathes our planet and formed the womb from which life emerged was delivered to earth from innumerable asteroid and comet collisions over a billion years. More amazing is that we have recently detected amino acids the building blocks of proteins, and nucleobases a key part of DNA in space. These have been created in comets and asteroids by the action of sunlight on base elements. This offers the possibility that asteroids may have brought the very building block from life itself.

Science is truly amazing, I find these discoveries inspiring and the mechanisms of creation beautiful. Creation is comprised of many processes often simple but built up with astonishing complexity, and conducted over eons of time and distance. All the zinc in you body for example was created as an ancient star exploded in a supernova and blew the stardust from which you are made across the galaxy.

Sure beats the whole thing being cobbled together in six days!

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