Asteroid 2014 AY28 passed the Earth at a distance of roughly 6 418 000 km (over 16 times the distance between the Earth and the Moon), slightly before 3.35 am GMT on Monday 17 March 2014. There was no danger of the asteroid hitting us, though had it done so it would have presented a realistic threat. 2014 AY28 is calculated to be between 82 and 260 m in diameter, and an object towards the upper end of this range would be expected to punch straight through the Earth's atmosphere, impacting the ground directly in an explosion over 460 times as large as that caused by the Hiroshima bomb, and creating a crater over 4 km in diameter. Such an event would cause devastation over a wide area, and could potentially cause climatic disruption lasting decades.
The calculated orbit of 2014 AY28. JPL Small Body Database Browser.
2014 AY28 was discovered on 4 January 2014 by the University of Hawaii's PANSTARRS telescope on Mount Haleakala. The designation 2014 AY28 implies that it was the 724th asteroid discovered in the first half of January 2014 (period 2014 A).
While 2014 AY28 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 262 day orbit that takes it from 1.02 AU from the Sun (1.02 times the distance at which the Earth orbits the Sun), slightly outside our orbit, to 1.82 AU from the Sun, (1.82 times the distance at which the Earth orbits the sun and outside the orbit of the planet Mars). As a Near Earth Object that remains strictly outside the orbit of the Earth it is classed as an Amor Family Asteroid. However, unlike most of the Amor Family, it is classed as a Potentially Hazardous Asteroid, due to its large size, and the closeness to which it approaches our orbit.
See also Potentially Hazardous Asteroid 357622 (2005 EY95) passes the Earth, Asteroid 2014 AM29 passes the Earth, Asteroid 2014 AZ32 passes the Earth, Asteroid 2014 AW32 passes between the Earth and the Moon on the day it is discovered and Asteroid 2014 AD16 passes by the Earth.
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