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Asteroid on Collision Course with the Earth ?

Science fiction movies such as Armageddon, Meteor, Deep Impact, and When Worlds Collide show various scenarios where items in space are on collision course with the earth. How realistic is that? Ask any dinosaur and they'd say that it never happens. But surprise they were taken by! It has been suggested that the extinction of the dinosaurs, (and therefore the allowing of the creation of humankind), was caused by an asteroid impact.

Small impacts, in the ten megaton size range, hit the earth every few decades. It is a matter of luck that on average these things hit places like Tunguska (almost no population) rather than cities.

Very small impacts (the size of the Hiroshima atomic bomb) hit every few months and sometimes put the nuclear defence systems on alert! (Not that the nuclear defence systems are pointing at the impacter - it's pointing at opposing tribes on the earth).Asteroids? Do we feel lucky?

It would be a very good idea to have an advanced space program, so as to avoid going the way of the dinosaurs. Colonising other planets would be good for survival, but also having space-going technology improves the chance of being able to deflect asteroids away from the earth.

A few good contacts in this business:

Spaceguard UK

Spaceguard Centre (Powys, Cymru/Wales) - was http://www.spaceguarduk.com/centre.htm
Also see
Astronomy Hotels

Minor Planets Center

Comets and Asteroid Information Network - was http://www.spaceguarduk.com/cain.htm

Lord Sainsbury's Near-Earth Object Task Force Report

Also, a Search for "Minor Planets" sometimes finds helpful contacts. "Minor Planets" is a term which sometimes refers to asteroids!

If an asteroid is found to be on collision course with the Earth, the hope is to notice it soon enough. A few decades of warning may be enough to develop the space program so as to go visit the asteroid and start adjusting its course. Asteroids are big and travel very fast, and deflecting them requires a sustained effort over a long period. Still, it's worth doing, to save the Earth!

To calculate how many megatons of devastation are caused by an asteroid, multiply the weight of the asteroid (in millions of tonnes) by the square of (speed divided by 3km/second). So, if it's two million tonnes travelling at 30 kilometres per second, that's 200 megatons. Is this worth an extra page do you reckon?

It's likely this sort of thing will be taken more seriously after the next small impact by an asteroid, a few megatons, in the middle of the ocean. That would cause tidal waves on a global scale and might persuade governments to stop fighting each other and defend the planet instead. It's worth paying for a space program, in the long-run.

Note the juxtaposition in the photo, with the newspaper headline "Asteroid on Earth Collision Course" next to the National Lottery where people place their bets on the chance of something improbable happening.

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