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Astronomers Discover Trojan Asteroid in Earth's Orbit


Earth has been playing "follow the leader" with a trojan asteroid for thousands of years. The first near-Earth object other than the moon to have ever been identified, TK7 shares the same orbit as our planet but about 50 million miles ahead of Earth.

NASA explains:

Trojans are asteroids that share an orbit with a planet near stable points in front of or behind the planet. Because they constantly lead or follow in the same orbit as the planet, they never can collide with it. In our solar system, Trojans also share orbits with Neptune, Mars and Jupiter. Two of Saturn's moons share orbits with Trojans.

Scientists had predicted Earth should have Trojans, but they have been difficult to find because they are relatively small and appear near the sun from Earth's point of view.

"These asteroids dwell mostly in the daylight, making them very hard to see," said Martin Connors of Athabasca University in Canada, lead author of a new paper on the discovery in the July 28 issue of the journal Nature. "But we finally found one, because the object has an unusual orbit that takes it farther away from the sun than what is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at Earth's surface."

The object is about 1,000 feet in diameter and should not come closer than 15-million miles, at least for the next 100 years. Astronomers say such asteroids could be useful in the future for mining precious metals.

Watch a video, showing the asteroid's orbit in relation to Earth's, AFTER THE JUMP...

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  1. Fascinating!

    Posted by: Scott | Jul 29, 2011 9:57:32 AM

  2. "Astronomers say such asteroids could be useful in the future for mining precious metals."

    Yeah, ask Ripley how that's going.

    Posted by: Really? | Jul 29, 2011 9:58:34 AM

  3. How does this celestial body affect NEOs, comets and they like as they pass near the Earth? Would something like this be too small or too far away to even have an effect? Or, would it have just enough of a gravitational pull to affect an NEOs trajectory such that it would keep us safe or result in a cataclysmic event?


    Posted by: Marc C | Jul 29, 2011 10:02:38 AM

  4. How do we know there isn't another earth-sized planet in earth's orbit hiding on the other side of the sun?

    Posted by: JD | Jul 29, 2011 10:17:46 AM

  5. 1000 feet in diameter is too small to have much gravitational impact on anything.

    Is there another earth-sized planet hiding on the other side of the sun? Why would you think there was? Why not an earth sized meatball, or a giant mass of teletubbies?

    Another earth sized planet in our system would have some fairly obvious gravitational effects, even if we couldn't see it.

    Posted by: BaconBacon | Jul 29, 2011 10:29:03 AM

  6. Andy, I'm not saying you should quit writing about gay things, but for some reason your posts on astronomy are always my favorite.

    Posted by: Gregoire | Jul 29, 2011 10:30:32 AM

  7. We know there is no "counter-Earth" on the other side of the Sun simply because we don't see anything there. We have numerous deep space observation probes far away from the earth continuously staring at the sun whose field of view includes the volume of space directly behind the sun from the vantage point of Earth. There's simply nothing there.

    Posted by: No | Jul 29, 2011 11:17:49 AM

  8. It would be a good idea to colonize this "Trojan" with an alternative colony of progressive minded people. Then we'd have a good place to escape to when things start to get really crazy here.

    Posted by: Paul | Jul 29, 2011 11:27:57 AM

  9. Does this make us a "Dwarf Planet" since we haven't cleared our orbit from debris?

    Posted by: Carl | Jul 29, 2011 12:32:06 PM

  10. Umm, I'd like to see that same video with the MOON included and it's gravitational pull included too!

    Posted by: Peter | Jul 29, 2011 12:37:13 PM

  11. First Congress can't get its act together and now THIS!

    At its furthest point this piece of rock ends up just opposite to the Earth at the other side of the sun. Then it swings back like it would smack into us. I dunno, I'm not sure I like that. Can't we just blow it up?

    Posted by: Chicken Little | Jul 30, 2011 7:32:49 PM

  12. i got it through search engine and like it and hope you will post some more new and unique

    Posted by: editor | Jul 31, 2011 4:13:49 AM

  13. great article indeed thanks for posting such info

    Posted by: editor | Jul 31, 2011 4:14:52 AM

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