Earth has a new sidekick. Astronomers have spotted a small asteroid traveling around our sun in the same general path as our planet. The 300-meter-wide rock, dubbed 2010 TK7, is Earth's first so-called "Trojan" asteroid, a class of bodies that gets its name from the asteroids that orbit the sun at the gravitationally stable points 60° ahead of and 60° behind Jupiter—which, according to astronomical convention, are individually named after prominent figures from the Trojan War (Brad Pitt excepted). Besides the thousands of Trojans that co-orbit the sun with Jupiter, astronomers have discovered a handful that co-orbit the sun with Neptune and Mars. 2010 TK7 isn't a threat to Earth. For one thing it's ahead of us, not behind us. And its current orbit brings it no closer than 20 million kilometers or so once every 395 years. Call it a partner for life, or at least for the next 5000 years, the period for which astronomers can reliably predict its chaotic orbit (which, relative to earth, is depicted in green loops).
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