Saturday 12 December 2015

Asteroid 2015 SV2 passes the Earth.

Asteroid 2015 SV2 passed by the Earth at a distance of 14 800 000 km (38.5 times the average distance between the Earth and the Moon, or 9.89% of the average distance between the Earth and the Sun), at about 3.45 pm GMT on Saturday 5 December 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a considerable threat. 2015 SV2 has an estimated equivalent diameter of 120-390 m (i.e. it is estimated that a spherical object with the same volume would be 120-390  m in diameter), and an object of this size would pass through the atmosphere and directly impact the ground with a force of about 50-2500 megatons (roughly 2940 to 147 000 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater about 1.5-5.5 kilometers across, and resulting in global climatic problems that could last for decades or even centuries.
 
 The calculated orbit of 2015 SV2. JPL Small Body Database.
 
2015 SV2 was discovered on 21 September 2015 (75 days before its closest approach to the Earth) by the Defense Advanced Research Projects Agency's Space Surveillance Telescope. The designation 2015 SV2 implies that it was the 71st asteroid (asteroid V2) discovered in the second half of September  2015 (period 2015 S).
  
2015 SV2 has an 1423 day orbital period and an eccentric orbit tilted at an angle of 6.48° to the plane of the Solar System that takes it from 1.06 AU from the Sun (i.e. 106 % of the average distance at which the Earth orbits the Sun) to 3.89 AU from the Sun (i.e. 389% of the average distance at which the Earth orbits the Sun, considerably over twice times the distance at which the planet Mars orbits). It is therefore classed as an Amor Group Asteroid (an asteroid which comes close to the Earth, but which is always outside the Earth's orbit). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in October 1972 and the next predicted in January 2047. 
 
See also...
  
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http://sciencythoughts.blogspot.co.uk/2015/12/asteroid-2004-xk14-passes-earth.htmlAsteroid 2004 XK14 passes the Earth.   Asteroid 2004 XK14 passed by the Earth at a distance of 14 720 000 km (38.3 times the average distance between the Earth and the Moon, or 0.84% of the average distance between the Earth and the Sun), slightly after 7.40 pm GMT on Friday 28...
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