Saturday 17 November 2018

Asteroid 2018 VX1 passes the Earth.

Asteroid 2018 VX1 passed by the Earth at a distance of about 381 300 km (0.99 times the average distance between the Earth and the Moon, or 0.25% of the distance between the Earth and the Sun), at about 6.20 pm GMT on Saturday 10 November 2018. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2018 VX1 has an estimated equivalent diameter of 5-19 m (i.e. it is estimated that a spherical object with the same volume would be 5-19 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 40 and 24 km above the ground, with only fragmentary material reaching the Earth's surface.

120 second image of 2018 VX1 taken with the Elena Planetwave 17" Telescope at Ceccano in Italy on 10 November 2018. The asteroid is the small point at the centre of the image, the longer lines are stars, their elongation being caused by the telescope tracking the asteroid over the length of the exposure. Gianluca Masi/Virtual Telescope.

2018 VX1 was discovered on 4 November 2018 (six days before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2018 VX1 implies that the asteroid was the 48th object (object X1) discovered in the first half of November 2018 (period 2018 V).

The calculated orbit of 2018 VX1. Minor Planet Center.

2018 VX1 has an 583 day orbital period and an eccentric orbit tilted at an angle of 2.79° to the plane of the Solar System, which takes it from 0.94 AU from the Sun (i.e. 94% of he average distance at which the Earth orbits the Sun) to 1.79 AU from the Sun (i.e. 179% of the average distance at which the Earth 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). As such the asteroid has occasional close encounters with the planet Earth, which it last came close to in December 2010, and is expected to do so again in October 2026. The asteroid also has occasional close encounters with the planet Mars, which it last came close to in April 1986 and is next predicted to pass in December 2026.

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