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.
Something striking head-on, ie, slowing down the Moon, could cause the Moon itself to start wandering in, but that would mean the Moon would have to be solid like a pool ball. An impact big enough to move the Moon in that manner would blow out huge chunks of junk, and some of that would rain down on the Earth, causing problems.
Without the Moon, the tilt of Earth's spin axis would vary chaotically between 0 and 85 degrees.Really... I thought pole shift would never, ever work because the Earth is an oblate spheroid.
Oh, cool! Chandler wobble, huh? Never heard of it. Gonna spend some time checking out those threads, thanks!
lol ;)
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.
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I don't think it would qualify as hardware . . .
but I wonder if we could position Scuba Teddy's buttocks such that we could precision guide his farts. Surely the old windbag has enough wind to change the course of some pretty big asteroids?
Me, too; maybe dead.
Oops, I meant to include a pointer to this:
http://www.freerepublic.com/focus/news/1636627/posts?page=62#62
Worst of all, the Moonbats!
Shumaker or Levy. I think technically they are amateur astronomers.David Levy (it sez here) is indeed an amateur astronomer, and Eugene Shoemaker (deceased) was a geologist, and Carolyn Shoemaker was trained as an astronomer. Carolyn has the most comet discoveries of any person in history (the record is now held by a machine, and it will be forever).
I would just 'reshape' itself like it did at the end of the Ice Age when the weight of the ice was redistributed around the world. Look for gawdawful earthquakes, volcanos, tsunamis, land suddenly sinking and rising and etc.
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