Tuesday 13 March 2018

Asteroid 2017 VR12 passes the Earth.

Asteroid 2017 VR12 passed by the Earth at a distance of about 1 445 000 km (3.76 times the average distance between the Earth and the Moon, or 0.97% of the distance between the Earth and the Sun), slightly before 7.55 am GMT on Wednesday 7 March 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2017 VR12 has an estimated equivalent diameter of 1040-450 m (i.e. it is estimated that a spherical object with the same volume would be 140-450 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 8250 to 175 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 2-8 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.

 Short animation of 2017 VR12 (still object at centre of image). Animation made up of 120 individual images taken on 7 March 2018, when the asteroid was at its closest.  Gianluca Masi/Virtual Telescope/Michael Swartze/Tenegra Observatory.
2017 VR12 was discovered on 10 November 2017 by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2017 VR12 implies that it was the 317th asteroid (asteroid R12) discovered in the first half of November 2017 (period 2017 V).

The calculated orbit of 2017 VR12. Minor Planet Center.

2017 VR12 has a 585 day orbital period and an eccentric orbit tilted at an angle of 9.22° to the plane of the Solar System, which takes it from 1.00 AU from the Sun (i.e. the average distance at which the Earth orbits the Sun) to 1.73 AU from the Sun (i.e. 173% of the average distance at which the Earth orbits the Sun, and more distant 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). This means that close encounters between the asteroid and Earth are extremely common, with the last having occurred in June 2010 and the next predicted in March 2026. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2017 VR12 is also classified as a Potentially Hazardous Asteroid.

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