Asteroid 2017 WG28 passed by the Earth at a distance of about 644 500 km (1.68 times the average distance between the Earth and the Moon, or 0.43% of the distance between the Earth and the Sun), at about 10.00 pm GMT on Friday 24 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 WG28 has an estimated equivalent diameter of 5-18 m (i.e. it is estimated that a spherical object with the same volume would be 5-18 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 25 km above the ground, with only fragmentary material reaching the Earth's surface.
The calculated orbit of 2017 WG28. Minor Planet Center.
2017 WG28 was discovered on 27 November 2017 (three days after 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 2017 WG28 implies that the asteroid was the 807th object (object G28) discovered in the second half of November 2017 (period 2017 W).
2017 WG28 has a 1458 day orbital period and an eccentric orbit tilted at an angle of 0.75° to the plane of the Solar System, which takes it from 0.99 AU from the Sun (i.e. 99% of he average distance at which the Earth orbits the Sun) to 4.04 AU from the Sun (i.e. 404% of the average distance at which the Earth orbits the Sun, more than twice 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 VC14 has occasional close encounters with the Earth, which it last came close to in January 2010. The asteroid also has occasional close encounters with the planet Mars, which is last passed in November 2010.
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