Asteroid (462959) 2011 DU passed by the Earth at a distance of 5 828 000 km
(15.2 times the average distance between the Earth and the Moon, or 3.90% of
the average distance between the Earth and the Sun), at about 8.30 pm
GMT on Thursday 6 October 2016. There was no danger of
the asteroid hitting us, though had it done so it would have presented a
considerable threat. (462959) 2011 DU
has an estimated equivalent
diameter of 130-380 m (i.e. a spherical body with the same mass would be 130-380 m in diameter), and an asteroid of this size
would be expected to pass through the atmosphere and directly impact the ground with a
force of 31-2500 megatons (1800-147 000 times the
explosive energy of
the Hiroshima bomb), causing devastation over a wide area and creating a
crater roughly 4.6-7.5 km across, and resulting in global climatic problems
that
could last for decades or even centuries.
The calculated orbit of 2016 TD. Minor Planet Center.
(462959) 2011 DU was discovered on 22 February 2012 by the University of Arizona's Kitt Peak-Spacewatch Project at the Steward Observatory in
the Catalina Mountains north of Tucson. The designation 2011 DU implies
that it was the twentieth asteroid (asteroid D) discovered in the second
half of February 2011 (period 2011 D), while
the designation 462959 implies that it was 462 959th asteroid ever
discovered (asteroids are not given this longer designation immediately
to avoid naming double or false sightings).
(462959) 2011 DU has a 464 day orbital period and an eccentric orbit tilted at an angle of 2.95° to the plane of the Solar System, that
takes it from 0.80 AU from the Sun (i.e. 80% of the average distance at
which the Earth orbits the Sun) to 1.54 AU from the Sun (i.e. 154% of
the average distance at which the Earth orbits the Sun,
outside the orbit of the planet Mars). 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 close encounters between the
asteroid and Earth are extremely common, with the last having occurred
in December 2011 and the next predicted in April 2020. As
an asteroid possibly larger than 150 m in diameter that occasionally
comes within 0.05 AU of the Earth, (462959) 2011 DU is also classified
as a Potentially Hazardous Asteroid. (462959) 2011 DU also has occasional close encounters with the planet Venus, with the last thought to have happened in August 1983 and the next predicted for December 2022.
See also...
Asteroid 2016 TH passes the Earth. Asteroid
2016 TH passed by the Earth at a distance of 128 300 km (0.34 times
the average distance between the Earth and the Moon, 0.09% of
the average distance between the Earth and the Sun), at about 4.30 pm GMT on Monday 3 October 2016...
Asteroid 2016 TD passes the Earth. Asteroid
2016 TD passed by the Earth at a distance of 226 200 km (0.59 times
the average distance between the Earth and the Moon, 0.15% of
the average distance between the Earth and the Sun), at about 5.15 pm GMT on Friday 30 September 2016... 
Fireball over the Eastern Great Lakes region. The American Meteor Society has
received reports of a bright fireball meteor being seen over parts of
the Eastern Great Lakes region slightly after 10.35 pm on Tuesday 4
October 2016 Eastern Daylight Time (slightly after 2.35 am on Wednesday 5...
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