|
Posted by The Plankmeister on September 9, 2005, 10:47 am
Please log in for more thread options
> http://www.mso.anu.edu.au/news/media_releases/media_release_050907.php
>
> Comet collision 'Armageddon' unlikely
>
> But odds greater than winning Lotto jackpot, ANU astronomer finds
> Australian National University
> September 7, 2005
>
> The chances of the Earth being hit by a comet from beyond Pluto - a la
> Armageddon - are much lower than previously thought, according to new
> research by an ANU astronomer.
>
> Using computer simulations and data from an American military
> telescope,
> Dr Paul Francis, from the ANU Research School of Astronomy and
> Astrophysics at Mt Stromlo, has found there are seven times fewer
> comets
> in our solar system than previously thought.
>
> 'I calculate that small comets, capable of destroying a city, only hit
> the Earth once every 40 million years or so," Dr Francis said. "Big
> continent-busting comets, as shown in the movies Armageddon and Deep
> Impact, are rarer still, only hitting once every 150 million years or
> so. So I don't loose sleep over it, but you're still more likely to be
> killed by a comet than to win the jackpot at Lotto."
Surely if that were so, then there'd be a whole bunch of people every week
killed by meteorites? I can't remember the last time I heard of anyone
killed by a meteorite. But I can say with certainty that there must have
been 100s of 1000s of lotto winners over the years....
> Previous estimates of the number of comets were based on the work of
> amateur astronomers, who for hundreds of years have been scanning the
> skies, looking for new comets.
>
> Previously, it was believed that these amateur astronomers were only
> spotting three per cent of the comets passing close to the Earth: the
> rest were thought to be missed because they were in the wrong part of
> the sky or were too faint.
>
> But Dr Francis found that the amateurs were doing better than anyone
> had
> realised - they were actually spotting 20 per cent of comets. There are
> therefore far fewer undiscovered comets.
>
> "The new data allowed us to count the number of faint and far-away
> comets that the amateurs had missed. And we found that they were pretty
> rare," Dr Francis said.
>
> These results apply to comets coming from beyond the orbit of Pluto,
> which is where most comets live. The Earth is still at risk of being
> hit
> by asteroids, and by so-called short-period comets - ones that come
> past
> repeatedly, like Halley's comet.
>
> "But asteroids and short-period comets come past again and again, so if
> we're clever enough we can find them all and predict which, if any,
> will
> hit the Earth," said Dr Francis. "If we find one on a collision course
> with the Earth, we would normally have hundreds of years warning in
> which to do something about it, like deflecting the asteroid.
>
> "The comets coming from beyond Pluto, so called long-period comets, are
> nastier, as they are totally unpredictable, and if we see one on a
> collision course we'd have at best one or two years warning - not long
> enough to do anything."
>
> Dr Francis' research has been accepted for publication in the
> Astrophysical Journal. It was based on computer simulations, published
> data from the Lincoln Near Earth Asteroid Research Project at White
> Sands Missile Range in New Mexico, and on data from amateur astronomers
> around the world.
>
> Further Information
>
> Background material on Dr Francis' research
>
> http://www.mso.anu.edu.au/~pfrancis/comets/
>
| 
XML Sitemap