Asteroid 2009 TK passed by the Earth at a distance of 6 747 000 km (17.5 times the average distance between the Earth and the Moon, or 4.51% of the average distance between the Earth and the Sun), slightly after 11.50 am GMT on Monday 5 October 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a considerable threat. 2009 TK has an estimated equivalent diameter of 65-210 m (i.e. a spherical body with the same mass would be 65-210 m in diameter), and an object towards the upper end of this range would pass through the atmosphere and directly impact the ground with a force of about 275 megatons (about 16 200 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater over 3 km across, and resulting in global climatic problems that could last for years or even decades.
The calculated orbit of 2009 TK. JPL Small Body Database.
2009 TK was first observed by Siding Spring Observatory in New South Wales on 8 October 2009. The designation 2009 TK indicates that it was the 10th asteroid (asteroid K) discovered in the first half of October 2009 (peroid 2009 T).
2009 TK has a 547 day orbital period and an eccentric orbit tilted at an angle of 20.2° to the plane of the Solar System that takes it from 1.04 AU from the Sun (i.e. 104 % of the average distance at which the Earth orbits the Sun) to 1.57 AU from the Sun (i.e. 1.57% of the average distance at which the Earth orbits the Sun, slightly over the average distance at which the planet Mars orbits). It is therefore classed as an Amor Group Asteroid (an asteroid which comes close to the Earth, but which is always outside the Earth's orbit). This means that close encounters between the asteroid and Earth are fairly common, with the most recent having occurred in October 2012 and the next predicted in October 2018. 2009 TK also has occasional close encounters with the planet Mars, the last having occurred in March 1967 and the next predicted for January 2018.
See also...
Asteroid (445830) 2012 CL19 passed by the Earth at a distance of 6 687 000 km (17.4 times the average distance between the Earth and the Moon, or 4.47% of the average distance between the Earth and the...
Asteroid 2015 RM83 passed by the Earth at a distance of 15 580 000 km (40.5 times the average distance between the Earth and the Moon, or 10.4% of the average distance between the Earth and the Sun), slightly before 6.20 am GMT on Saturday 12...
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