New NEA passed within 2 Earth radii last March

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ai_sci

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<font color="yellow">Closest by far<br /><br />The Minor Planet Center (MPC) took the highly unusual step overnight of issuing a circular (MPEC 2004-Q22) announcing the discovery of a tiny asteroid, 2004 FU162, observed for less than an hour last March. But what an arc that was, coming to almost one Earth radius from Earth's surface, which is by far the closest ever observed astrometrically (see “Closest observed flyby”).<br /><br />The circular states that “This object passed some 0.000086 AU (=13000 km) from the center of the earth on 2004 Mar. 31.65.” And the MPC Closest Approaches page, which had to add another decimal point to list this asteroid's distance, footnotes the distance as 12,900 km. = 8000 miles. Earth's mean radius is about 6,371 km. = 3,956 miles.<br /><br />Only four observations are reported, all from the U.S. Air Force/MIT LINEAR program early on March 31st. But this was enough for Steve Chesley at the NASA/JPL NEO Program Office to now calculate the object's orbit before and after being perturbed by the close passage.<br /><br />Gareth Williams explains in the circular that, “Although the observed arc is only 44 minutes, the orbit is quite determinate and, given the exceptional nature of this close approach, the object is now receiving a designation.” </font><br /><br />Slashdot <div class="Discussion_UserSignature"> </div>
 
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jitte

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The story went on to say: <br /><br />"From the estimated brightness of 2004 FU162, a standard formula can be used to roughly derive its diameter as six meters/yards. At that size, if it had entered Earth's atmosphere, it would have destructed harmlessly, although spectacularly, before reaching the ground."<br /><br />http://hohmanntransfer.com/mn/0408/22.htm#04fu162<br /><br /><br />Toutatis will pass at a distance of 962,951 miles 9-29-04 and is supposed to be the closest pass of a "known" NEO this century.
 
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jitte

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I should have said the closest pass of a "known" NEO as large as Toutatis. Toutatis is about 2.9 miles long and 1.5 miles wide.<br /><br />They don't have to be as big as Toutatis to cause considerable damage, the Tunguska event was thought to have been caused by an object about 165 feet across.<br /><br />
 
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