Monday 18 September 2017

Asteroid 2017 RV2 passes the Earth.

Asteroid 2017 RV2 passed by the Earth at a distance of about 832 100 km (2.17 times the average distance between the Earth and the Moon, or 0.56% of the distance between the Earth and the Sun), slightly before 2.25 am GMT on Tuesday 12 September 2017. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2017 RV2 has an estimated equivalent diameter of 11-34 m (i.e. it is estimated that a spherical object with the same volume would be 11-34 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 30 and 15 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2017 RV2  Minor Planet Center.

2017 RV2 was discovered on 14 September 2017 (two days after its closest approach to the Earth) by the Atlas MLO Telescope at Mauna Loa Observatory in Hawaii. The designation 2017 RV2 implies that the asteroid was the 71st object (object V2) discovered in the first half of September 2017 (period 2017 R). 

2017 RV2 has a 691 day orbital period and an eccentric orbit tilted at an angle of 0.21° to the plane of the Solar System, which takes it from 0.98 AU from the Sun (i.e. 98% of he average distance at which the Earth orbits the Sun, slightly inside the orbit of Venus) to 2.08 AU from the Sun (i.e. 208% of the average distance at which the Earth orbits the Sun, considerably more than the distance at which the planet Mars orbits). 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 close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in June 2002 and the next predicted in June 2019. 

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