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    HOME, HOME ON LAGRANGE: EARTH FINDS ITS TRUE COMPANION?

    By acanuck on Wed, 07/27/2011 - 6:51pm |

    Meanwhile, in non-debtpocalypse news, I read today that a Canadian-led team of astronomers has discovered Earth's "First Asteroid Companion," the as-yet-unnamed 2010 TK7.

    Fascinating -- except that the headline is totally wrong. None of the articles I scanned today mention it, but we've known about another "asteroid companion" for nearly a quarter-century. It's called Cruithne (pronounced KROOeee-nyuh), and it orbits the sun in a somewhat more elliptical version of Earth's path.

    Its year is synchronized within about a day of ours, with the result that it makes a close approach every November. It's also a far more substantial object than 2010 TK7 -- at roughly three miles in diameter, Cruithne is 15 times as wide and hundreds of times as massive. At one point, some were calling it "Earth's second moon," but that was clearly wrong, since it doesn't orbit our planet at all. Worth a google, though.

    Ars Technica is one of the handful of publications that got today's story right, calling 2010 TK7 "Earth's First Trojan Companion." That's because, unlike Cruithne, TK7's orbit is linked to at least one of Earth's Lagrangian points. Ars Technica explains it nicely:

    http://arstechnica.com/science/news/2011/07/astronomers-find-earths-first-trojan-asteroid.ars

    An argument could be made that TK7 may not really be a Trojan, since it appears to wander between Lagrange 3 and 4, and its discoverers concede its orbit may not be stable or predictable beyond 250 years. Cruithne, on the other hand, appears to have co-orbited with Earth for at least a million years.

    There are a bunch of smaller objects that also do weird horseshoe-shaped dances with Earth, and some even get temporarily captured into our orbit. Like I said, fascinating stuff.

    So there it is. Hope this post took your minds temporarily off the debt-ceiling "debate." Damn those Republicans! Damn them to hell! Sorry, the celestial calming effect seems to wear off pretty fast. 

     

    Comments

    Interesting. I just revisited Google News on this story, and lots more headlines now read "First Trojan" as opposed to this morning's "First Asteroid Companion." I didn't check how many mention Cruithne, but it's clear the initial reporting got some nerd feedback.


    by acanuck on Wed, 07/27/2011 - 7:03pm

    Thanks acanuck! It's a truly interesting story, and the bit about Cruithne is even more fascinating.


    by Verified Atheist on Wed, 07/27/2011 - 8:27pm

    What a rush!  Nice work Ack. smiley


    by Bruce Levine on Wed, 07/27/2011 - 9:22pm

    Lovely.  Yes,  I do feel better now.   Thanks for sharing.  I may take this as my screen name someday:  Cruithne (pronounced KROOeee-nyuh)


    by Ramona on Wed, 07/27/2011 - 10:34pm

    Best headline for this story.  Bravo!


    by Johnny Cashed (not verified) on Thu, 07/28/2011 - 3:32pm

    It's been a good week in the asteroid field. Launched nearly four years ago, the Dawn probe has finally parked itself off Vesta, and is sending back spectacularly detailed photos. After studying that asteroid for about a year, Dawn will head off toward the dwarf planet Ceres. Expect to see photos of it in 2015, assuming NASA's still in business.


    by acanuck on Thu, 07/28/2011 - 5:27pm