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April 10, 2011

Newly Discovered Asteroid is Earth's Companion

Astronomers have found a 200-400 meter wide asteroid to have been following Earth in its orbit for at least a quarter million years. The asteroid's average distance from the Sun is identical to that of Earth's and it is known to be the largest of Earth's so-called "horseshoe" asteroids which mimic closely to the orbital motion of our planet around the Sun and appear to trace out a horseshoe shape in space. The asteroid takes 175 years to move from one end of the horseshoe to the next and it is now currently near the end of the horseshoe, trailing Earth. However, even though its orbit is remarkably similar to Earth's, it keeps well away from the Earth and has never came closer to our planet than 50 times the distance to our moon in several hundred thousand years. Multiple hypotheses are being made by astronomers to figure out exactly how the asteroid came into this horseshoe shaped orbit around Earth.

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Posted by schultka at April 10, 2011 04:41 PM


I think it's so cool when new asteroids and different objects are found in space! Outer space is so crazy to think about because we just do not know what is out there! It is interesting that its average distance from the Sun is identical to Earth's! Maybe this asteroid is a result from the giant impact that we talked about earlier in the semester.

Posted by: melmccor at April 10, 2011 07:13 PM

I did think it was weird that there is an asteroid that seems too timid to follow Earth around its full orbit. So I did some research and found an article that seems to say that this horseshoe-shaped orbit can be attributed to BOTH the Sun's and Earth's gravitational pull. And also it seems like this asteroid is going to be around for a while according to this article, so I am very sure that we will have plenty of time to gather enough data to make the correct conclusion.

Here is the article I found: http://www.dailymail.co.uk/sciencetech/article-1374054/Earth-joined-giant-asteroid-sun-unusual-horseshoe-pattern.html

Posted by: jeffkong at April 11, 2011 05:05 PM

Interesting post. I think this also speaks to the number of asteroids following us that haven't even been discovered yet. I looked into the method of detection of this new asteroid and found that it was discovered by the Wide-field Infrared Survey Explorer (WISE) which took 1.5 million infrared images of the sky in hopes to discover unknown asteroids, comets, etc. It found tens of thousands, but what stuck out to me is that it also found 19 potentially hazardous asteroids that may be likely to hit Earth and would cause significant destruction if they did.

Posted by: emslade at April 11, 2011 09:44 PM

Like the person above me said, I think it really speaks volumes about the the number of asteroids that follow us and also the ones we have yet to discover. It seems quite interesting that the asteroid has come into this horseshoe shaped orbit but I would suspect the Sun's gravitational pull is the biggest reason for this. It will be interesting to see over time if we can find even more Earth-like orbits in our solar system as we discover more asteroids and perhaps in time we will find asteroids that may come very close in orbit to our own planet.

Posted by: nikraman at April 15, 2011 11:54 PM

I think it's strange that we have an asteroid in our orbit like this, given part of the nebular theory is that each planet eventually "clears out its neighborhood" as if forms. It seems like the more we learn the more holes we begin to find in the nebular theory, as is the case with the discovery of the "hot Jupiters" orbiting their suns so close in other solar systems.

Posted by: rborden at April 17, 2011 02:18 PM

Yes astronomers are very curious as to where it came from and have suggested several possibilities. For instance, it could just be an ordinary asteroid from the asteroid belt separating Mars and Jupiter. If this were true, random gravitational tugs of various planets would be responsible for its current orbit. I think this would be unlikely but definitely possible. It is also very relavent to the topics we are currently discussing in Astro101.

Posted by: aarthi at April 17, 2011 07:39 PM

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