Posted on 05/22/2006 4:52:42 PM PDT by blam
Risk of asteroid smashing into Earth reduced
12:50 22 May 2006
NewScientist.com news service
Kelly Young
The asteroid's path through the solar system will bring it to close to Earth in 2029 (Image: JPL/NASA)
The danger to Earth from an asteroid called Apophis, which once looked relatively likely to hit the Earth, appears to be waning.
The odds of an Earth impact by Apophis in 2036 have now been reduced from 1 in 5500 to 1 in 24,000, following new radar measurements taken by the Arecibo Observatory in Puerto Rico.
On 6 May 2006, with the asteroid 42 million kilometres away, astronomers with NASA's Jet Propulsion Laboratory measured the speed of the asteroid with radar. They found its speed was 6 millimetres per second different than what they had expected.
"It's just a small correction in the orbit that propagates forward in time enough to reduce the probability of impact," says Jon Giorgini, senior analyst with the Solar System Dynamics Group at JPL in Pasadena, California, US.
Before this observation, it was thought that in 2029 Apophis would approach our planet to within about 5.86 Earth radii. With these new measurements, the estimated distance has been pushed back to 5.93 Earth radii.
Through the keyhole This seemingly small difference is crucial since if the asteroid's path carries it through a certain "keyhole" – in this case, a specific region of space near Earth just 600 metres across – Apophis's orbit could be perturbed enough to put it on a collision course with Earth in 2036.
The asteroid, which is about 320 metres in diameter, ranks a 1 on the Torino scale. Zero means an object has no chance of hitting Earth and a 10 means certain impact. At one point, Apophis rated a 4.
Because the asteroid will travel too close to the Sun for radar measurements, this will probably be the last chance to get good radar data of Apophis for several years. But in 2013, the asteroid should be in a position where astronomers can track it with radar again.
"I think we'll be able to put this to rest one way or the other," Giorgini told New Scientist.
Giggle factor However, astronomers may be able to get optical data on Apophis before then, says Dave Tholen, an astronomer with the University of Hawaii, US.
In January, Tholen and his team plan to observe Apophis to determine its rotation rate. This is important because if the asteroid is heated unevenly by sunlight, the radiation can impart a small force on the asteroid. That force may be miniscule, but when it accumulates over 20 years, it can make the difference in whether Apophis passes through the keyhole or not, he says.
Even though the odds of this particular asteroid hitting Earth have been reduced dramatically, its early threat alerted the public to the potential of asteroid impacts. "Compared to 10 years ago, I'd say the giggle factor has been reduced considerably," Tholen says.
Catastrophism ping.
Bush's fault.
I'll sleep much better now, thank you!
The odds of an Earth impact by Apophis in 2036 have now been reduced from 1 in 5500 to 1 in 24,000,
Oh, I know that makes ME feel so much better.....
That's a relief. Bruce Willis will be really old by 2036.
We have to wait until 2013 to find out? The suspense is killing me.
We'll all be dead from West Nile Virus, Bird Flu, or global warming by then.
The odds of collision are the same. Nobody has done anything to change the odds. We are no safer than we were. Now, if we really want to change the odds we need to actually do something such as put some hardware out in space so we can change the momentum vector. But, doing anything these days seems to take Congress and several $ billion and a declaration of human rights violations and investigations of charges of bribery and racism.
We'd probably push the wrong way and cause it to hit us.
Rove! Get that "Asteroid Destroys Earth" machine fixed... STAT!
I thought that it was Anubis who chucked the asteroid at us; not Apophis.
Whew, that brought the blood pressure down. Don't forget to ping us all again in 30 years.
Wow! If the doctor tells you the bullet missed your heart by 6 millimeters, d'ya feel lucky?
There is no guarantee it won't crash your computer, but it is a space flight simulator, and freeware.
Many of these asteroids are never spotted until they have just missed us. A prominent astronomer (forget the name, the one a few comets are named after) said he is convinced that if we are hit, we won't see it coming until the asteroid has slipped into the atmosphere.
At least then we wouldn't have the time to listen to liberals complaining.
The problem is that the object has to move against the starry background to be noticed, and the one coming right at you won't. It will just get bigger. Radar might work, but the return signal would be lost in background noise until the object is very close.
Bam.
:^O
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