Asteroid 2007 TV18 passed by the Earth at a distance of 2 841 000 km (a little under 7.4 times the average distance between the Earth and the Moon), slightly after midnight on Friday 18 April 2014. There was no danger of the asteroid hitting us, though had it done so it would have presented a genuine threat. 2007 TV18 is estimated to be between 33 m and 100 m in diameter, and an object towards the upper end of this range would be predicted to be able to punch straight through the Earth's atmosphere and impact the ground. This would result in an explosion over 2000 times as large as the one caused by the Hiroshima bomb, and create a crater over a kilometer in diameter, as well as devastation over a much wider area and climatic effects that would last for several years.
The calculated orbit of 2007 TV18. JPL Small Body Database Browser.
2007 TV18 was discovered on 9 October 2007 by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2007 TV18 implies that the asteroid was the 471st object (object V18) discovered in the first half of October 2007 (period 2007 T).
2007 TV18 has a 503 day orbital period and an eccentric orbit that takes it from 0.81 AU from the Sun (i.e. 81% of the average distance at which the Earth orbits the Sun) to 1.67 AU from the Sun (i.e. 167% of the average distance at which the Earth orbits the Sun, outside the orbit of the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).
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