Sunday 12 March 2017

Asteroid 2017 EV passes the Earth.

Asteroid 2017 EV passed by the Earth at a distance of 1 068 000 km (2.78 times the average distance between the Earth and the Moon, 0.71% of the average distance between the Earth and the Sun), slightly before 7.35 pm GMT on Sunday 5 March 2017. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2017 EV has an estimated equivalent diameter of 8-26 m (i.e. it is estimated that a spherical object with the same volume would be 8-26 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 35 and 20 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2017 EV. Minor Planet Center.

2017 EV was discovered on 4 March 2017 (the day before its closest encounter with the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2017 EV implies that it was the 21st asteroid (asteroid V) discovered in the first half of March 2017 (period 2017 E).

2017 EV is calculated to have a 592 day orbital period and an elliptical orbit tilted at an angle of 7.06° to the plain of the Solar System that takes it from 0.92 AU from the Sun (i.e. 92% of the average distance at which the Earth orbits the Sun) to 1.82 AU from the Sun (i.e. 183% of the average distance at which the Earth orbits the Sun, considerably more than 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 close encounters between the asteroid and Earth are extremely common, with the last having occurred in April 2017 and the next predicted in March 2015. 2017 EV  also has frequent close encounters with the planet Mars, with the last calculated to have happened in February 2011 and the next predicted for May 2022.

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