Asteroid (438955) 2010 LN14 passed by the Earth at a distance of about 9 025 000 km (23.5 times the average distance between the Earth and the Moon, or 6.03% of the distance between the Earth and the Sun), slightly before 10.40 pm GMT on Saturday 14 January 2017. There was no danger of the asteroid hitting us, though were it to do so it would have presented a considerable threat. (438955) 2010 LN14 has an estimated equivalent diameter of 110-360 m (i.e. it is estimated that a spherical object with the same volume would be 110-360 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 600-118 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 1.5-5 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.
The calculated orbit of (438955) 2010 LN14. Minor Planet Center.
(438955) 2010 LN14 was discovered on 6 June 2010 by the Tenegra II Telescope at Tenegra Observatries in Arizona. The designation 2010 LN14 implies that the asteroid was the 363rd object (object N14) discovered in the first half of June 2010 (period 2010 L), while the longer designation (438955 indicates that it was the 438 955th 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).
(438955) 2010 LN14 has a 453 day orbital period and an eccentric orbit tilted at an angle of 1.49° to the plane of the Solar System, which takes it from 0.61 AU from the Sun (i.e. 61% of he average distance at which the Earth orbits the Sun, less than the distance at which the planet Venus orbits the Sun) to 1.70 AU from the Sun (i.e. 170% of the average distance at which the Earth orbits the Sun, and considerably outside the orbit of 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 2015 and the next predicted in June 2020 As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, (438955) 2010 LN14 is also classified as a Potentially Hazardous Asteroid.
(438955) 2010 LN14 also has frequent close encounters with the planets Venus, which it is thought to have last passed in April 1962, and is next predicted to pass in April 2019, and Mars which it last came close to in January 1973 and is next predicted to pass in July 2023). Asteroids which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet.
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