Tuesday 21 November 2017

Asteroid 2017 VV12 passes the Earth.

Asteroid 2017 VV12 passed by the Earth at a distance of about 714 200 km (1.86 times the average distance between the Earth and the Moon,  or 0.48% of the distance between the Earth and the Sun), slightly before 3.15 pm GMT on Wednesday 15 November 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 VV12 has an estimated equivalent diameter of 4-15 m (i.e. it is estimated that a spherical object with the same volume would be 4-15 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 43 and 25 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2017 VV12. Minor Planet Center.

2017 VV12 was discovered on 14 November 2017 (the day before its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2017 VV12 implies that it was the 321st asteroid (asteroid V12) discovered in the first half of November 2017 (period 2017 V).
2017 VV12 has a 767 day orbital period and an eccentric orbit tilted at an angle of 0.15° to the plane of the Solar System, which takes it from 0.97 AU from the Sun (i.e. 97% of he average distance at which the Earth orbits the Sun) to 2.31 AU from the Sun (i.e. 231% of the average distance at which the Earth orbits the Sun, 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 2017 VV12 has occasional close encounters with the Earth, which it last came close to in February 199, and is next predicted to pass in January 2020, as well as the planet Mars, which it last came close to in April 1997.
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