Asteroid (369264) 2009 MS passed the Earth at a distance of 10 410 000 km (about 27.1 times the distance between the Earth and the Moon or 6.96% of the distance between the Earth and the Sun), slightly before 8.30 pm GMT on Wednesday 30 November 2016. There was no danger of the asteroid hitting us, though if were to do so it would present a significant threat. (369264) 2009 MS is estimated to be between 1000 and 3300 m in diameter, and an asteroid of this size would be expected to pass directly through the atmosphere, striking the Earth's surface and creating a crater over 13 km in diameter, as well as causing devastation over a wide area and global climatic effects that would potentially last for centuries.
The calculated orbit of (369264) 2009 MS. Minor Planet Center.
(369264) 2009 MS was discovered on 19 June 2009 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 2009 MS implies that the asteroid was the 18th object (object S) discovered in the second half of June 2016 (period 2009 M), while 369264 indicates that it was the 369 264th asteroid discovered overall (asteroids are not given this longer designation immediately, to ensure that numbered objects are genuine asteroids that have not been previously described).
(369264) 2009 MS is calculated to have a 1037 day orbital period and an elliptical orbit tilted at an angle of 52.4° to the plain of the Solar System that takes it from 0.86 AU from the Sun (i.e. 86% of the average distance at which the Earth orbits the Sun) to 3.14 AU from the Sun (i.e. 314% of the average distance at which the Earth orbits the Sun, more than twice 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 November 1999 and the next predicted in December 2033. As an asteroid possibly larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, (369264) 2009 MS is also classified as a Potentially Hazardous Asteroid.
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