Thursday was a short day at the conference. I had to check out of the hotel in the late morning, so I had time only to jump between two sessions (another exoplanet one, and one about near-Earth asteroids [NEAs]).
Editor's note: Liz is posting updates regularly from DPS09 to Twitter.com/AstronomyMag.
The exoplanet session focused on what I’ve noticed to be an extremely popular topic here at the conference — modeling exoplanet atmospheres. That’s good to hear, because a near future issue of Astronomy will feature an article about this. So make sure to keep an eye out for it!
I then headed over to the NEA session. This was interesting stuff. I haven’t heard much about Apophis lately … until these presentations. Apophis is the asteroid that was in the news about 5 years ago because astronomers predicted there was a chance as high as 1 in 37 of it slamming into Earth in 2029. Scientists quickly revised that prediction … but not after the public – and the media – freaked out about it. Now we know there’s a 0 percent chance the asteroid will hit our home planet in 2029.
There is a chance, however, that it could pass through a gravitational “keyhole.” This is a small window (about 600 meters in diameter) where the gravitational forces would set up a collision with Earth. But the chance of such a collision has now been downgraded to just 1 in 250,000 in 2036, said David Tholen of the University of Hawaii and Steven Chesley of Jet Propulsion Laboratory today at DPS. Following additional observations and modeling, Tholen’s group estimates Apophis could pass through another keyhole in 2067, which would send it on a 2068 collision course with Earth. This keyhole, however, is just 2m in diameter … that’s pretty tiny. The chance of impact is even smaller than 2036’s chances — about 1 in 333,000.
It sounds like we’re pretty safe from Apophis, but we’ll need more observations to determine whether this fact holds true for all the other NEAs out there. Upcoming large-scale surveys should provide some of these much-needed observations.
All right, I’m off to explore Puerto Rico’s El Yunque rainforest and bioluminescence bay. Then the Arecibo Observatory on Saturday.
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