Asteroid 2015 TA206 passed by the Earth at a distance of 18 560 000 km (48.3 times the average distance between the Earth and the Moon, or 12.4% of the average distance between the Earth and the Sun), slightly after 4.20 pm GMT on Friday 23 October 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a genuine threat. 2015 TA206 has an estimated equivalent diameter of 36-110 m (i.e. a spherical body with the same mass would be 36-110 m in diameter), and an object towards the upper end of this range would pass through the atmosphere and directly impact the ground with a force of about 45 megatons (about 2650 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater about 1.5 km across, and resulting in global climatic problems that could last for years or even decades.
The calculated orbit of 2015 TA206. JPL Small Body Database.
2015 TA206 was discovered on 13 October 2015 (ten days before its closest approach to the Earth) by the European Space Agency's Optical Ground Station on Tenerife in the Canary Islands. The designation 2015 TA206 implies that it was the 5151st asteroid (asteroid A206) discovered in the first half of October 2015 (period 2015 T).
2015 TA206 has an 1726 day orbital period and an eccentric orbit tilted at an angle of 9.84° to the plane of the Solar System that takes it from 1.09 AU from the Sun (i.e. 109 % of the average distance at which the Earth orbits the Sun) to 4.54 AU from the Sun (i.e. 454% of the average distance at which the Earth orbits the Sun, over three times the distance at which the planet Mars orbits and close to the orbit of Jupiter). 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).
See also...
Asteroid 2015 TG144 passed by the Earth at a distance of 5 109 000 km (13.3 times the average distance between the Earth and the Moon, or 3.42% of the average distance between the Earth and the Sun), slightly before 9.00 am on Friday 16 October...
Asteroid 2015 TC179 passed by the Earth at a distance of 4 733 000 km (12.3 times the average distance between the Earth and the Moon, or 3.16% of the average distance between the Earth and the Sun), slightly after 8.15 pm on Wednesday 14 October...
Asteroid 2015 TB25 passed by the Earth at a distance of 3 658 000 km (9.51 times the average distance between the Earth and the Moon, or 2.45% of the average distance between the Earth and the Sun), slightly before 7.55 pm GMT on Sunday 11 October...
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