Post by Chicago Astronomer - Astro Joe on Jun 1, 2005 23:30:36 GMT -6
Comet put on list of potential Earth impactors
13:17 01 June 2005
NewScientist.com news service
A comet has been added to the list of potentially threatening near-Earth objects maintained by NASA's Jet Propulsion Laboratory. Comet Catalina 2005 JQ5 is the largest - and therefore most potentially devastating - of the 70 objects now being tracked. However, the chances of a collision are very low.
The listing of Comet Catalina underscores the uncertainty in the knowledge of whether comets or asteroids pose a greater threat to Earth. Previous estimates of the proportion of the impact risk posed by comets have varied widely, from 1% to 50%, with most recent estimates at the lower end.
On 26 May, JPL's unique orbital calculation software determined that Comet Catalina was on what could possibly be a collision course with Earth, though the odds of such an impact were small: just 1 chance in 300,000 of a
strike on June 11, 2085. Based on the 980-metre size estimate, that would produce a 6-gigaton impact - equivalent to 6 billion tonnes of TNT.
Astronomers expected the addition of further observations to the calculations to rule out any possibility of a collision, as happens with most newly-seen objects.
But that did not quite happen. The comet's predicted pathway actually drew even closer to making a perfect bull’s-eye with the Earth - its predicted path passes within 1000 kilometres of the where the centre of our 12,700-km-diameter planet will be around that time.
However, uncertainty in the exact timing of the comet’s pass through the line of Earth’s orbit dropped the odds of an impact to about 1 in 120 million. That is very low, but the observations so far cannot categorically rule a collision out.
More at the NewScientist: www.newscientistspace.com/article/dn7449.html
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I think that the Earth is entering a high concentrated area of space debris.
I still of my hardhat at the ready.
