Friday 17 April 2015

Asteroid 2015 FL passes the Earth.

Asteroid 2015 FL passed by the Earth at a distance of 7 597 000 km (19.8 times the average distance between the Earth and the Moon, or 5.08 % of the average distance between the Earth and the Sun), at about 0.50 am GMT on Saturday 11 April 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a genuine threat. 2015 FL has an estimated equivalent diameter of 130-410 m (i.e. it is estimated that a spherical object with the same volume would be 130-410 m in diameter), and an object of this size would pass through the atmosphere and directly impact the ground with a force of about 65-3000 megatons (roughly 3800-175 000 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater 2-6 kilometers across, and resulting in global climatic problems that could last for years or possibly decades.
 
 The calculated orbit of 2015 FL. JPL Small Body Database.
 
2015 FL was discovered on 16 March 2015 (31 days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 FL implies that it was the eleventh asteroid (asteroid L) discovered in the second half of March 2015 (period 2015 F).
 
2015 FL has an 1606 day orbital period and an eccentric orbit tilted at an angle of 15.7° to the plane of the Solar System, which takes it from 0.94 AU from the Sun (i.e. 94% of the average distance at which the Earth orbits the Sun) to 4.43 AU from the Sun (i.e. 443% of the average distance at which the Earth orbits the Sun, nearly three times 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 while close encounters between 2015 FL and the Earth are rare, it does have fairly frequent close encounters with Jupiter, with the last having occured in April 2012 and the next predicted for September 2047.

See also...
 
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