Asteroid 2016 QA2 passed by the Earth at a distance of 86 570 km (0.23 times the average distance between the Earth and the Moon, 0.06% of the average distance between the Earth and the Sun, or 2.42 times the distance at which communication satellites in geostationary orbits orbit the Earth), slightly after 1.25 am GMT on Sunday 28 August 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2016 QA2 has an estimated equivalent diameter of 16-52 m (i.e. it is estimated that a spherical object with the same volume would be 16-52 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 25 and 8 km above the ground, with only fragmentary material reaching the Earth's surface.
Image of 2016 QA2 taken on 28 August 2016 from Ceccano in Italy. The asteroid is the point in the center of the picture. The longer lines are stars, their elongation being caused by the telescope traking the asteroid over the length of the exposure, in this case 60 seconds. Gianluca Masi/Virtual Telescope.
2016 QA2 was discovered on 27 August 2016 (only hours before its closest approach to the Earth) by the Southern Observatory for Near Earth Asteroids Research (SONEAR) at Oliviera in Minas Gerais State, Brazil. The designation 2016 NA implies that it was the fifty first asteroid (asteroid A2) discovered in the second half of August 2016 (period 2016 Q)
The calculated orbit of 2016 QA2. JPL Small Body Database.
2016 QA2 has a 350 day orbital period, with an elliptical orbit tilted at an angle of 15.7° to the plain of the Solar System which takes in to 0.76 AU from the Sun (76% of the distance at which the Earth orbits the Sun and slightly outside the orbit of the planet Venus) and out to 1.18 AU (18% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in August 2015 and the next predicted in August 2017. 2016 QA2 also has frequent close encounters with the planet Venus, with the last thought to have occurred in November 1996 and the next predicted for June 2045. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2016 QA2 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid.
See also...
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