Asteroid 2018 TP passed by the Earth at a distance of about 6 949 000 km (18.1 times the average distance between the Earth and the Moon, or 4.64% of the distance between the Earth and the Sun), slightly after 9.05 pm GMT on Tuesday 2 October 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2018 TP has an estimated equivalent diameter of 78-250 m (i.e. it is estimated that a spherical object with the same volume would be 78-250 m in diameter), and an object at the upper end of this range would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 35 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater more than 3.5 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.
The calculated orbit of 2018 TP. Minor Planet Center.
2018 TP was discovered on 1 October 2018 (the day before its closest approach to the Earth) by the Atlas MLO Telescope at Mauna Loa Observatory in Hawaii. The designation 2018 TP implies that the asteroid was the fifteenth object (object P) discovered in the first half of October 2018 (period 2018 T).
2018 TP has an 581 day orbital period and an eccentric orbit tilted at an angle of 19.0° to the plane of the Solar System, which takes it from 0.73 AU from the Sun (i.e. 73% of he average distance at which the Earth orbits the Sun, slightly outside the orbit of the planet Venus) to 1.99 AU from the Sun (i.e. 199% of the average distance at which the Earth orbits the Sun, and further from the Sun than 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). As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2018 TP is also classified as a Potentially Hazardous Asteroid.
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