Wednesday 18 October 2017

Asteroid 2017 RV1 passes the Earth.

Asteroid 2017 RV1 passed by the Earth at a distance of about 6 820 000 km (17.7 times the average distance between the Earth and the Moon, or 4.58% of the distance between the Earth and the Sun), slightly before 4.45 am GMT on Thursday 12 October 2017. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2017 RV1 has an estimated equivalent diameter of 180-570 m (i.e. it is estimated that a spherical object with the same volume would be 180-570 m in diameter), and an object of this size 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 12 000-600 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater over 2-8 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 2017 RV1. Minor Planet Center.

2017 RV1 was discovered on 12 September 2017 (thirty days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2017 RV1 implies that it was the 46th asteroid (asteroid V1) discovered in the first half of September 2017 (period 2017 R).

2017 RV1 has a 1377 day orbital period and an eccentric orbit tilted at an angle of 2.04° to the plane of the Solar System, which takes it from 0.89 AU from the Sun (i.e. 89% of he average distance at which the Earth orbits the Sun) to 3.94 AU from the Sun (i.e. 394% of the average distance at which the Earth orbits the Sun, considerably more than twice the distance at which the planet Mars orbits the Sun). 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). This means that the asteroid has occasional close encounters with the planet Earth, with the last thought to have occurred in September 2002 next predicted to occur in September 2036. It is also calculated to have occasional close encounters with the planet Jupiter, with the last thought to have happened in October 1970 and the next predicted for February 2031. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2017 SN2 is also classified as a Potentially Hazardous Asteroid (it comes no closer to the Sun than 105% of the average distance at which the Earth orbit's the Sun, but the Earth's orbit is not completely circular).

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