Asteroid
2016 UD passed by the Earth at a distance of 72 540 km (0.21 times the
average distance between the Earth and the Moon, 0.05% of the average distance
between the Earth and the Sun), slightly after 11.30 pm GMT on Monday 17
October 2016. There was no danger of the asteroid hitting us, though had it
done so it would have presented no threat. 2016 UD has an estimated
equivalent diameter of 9-28 m (i.e. it is estimated that a spherical object
with the same volume would be 9-28 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 32 and 20 km above the ground, with only fragmentary
material reaching the Earth's surface.
The calculated orbit of 2016 TO11. Minor Planet Center.
2016 UD was discovered on 19
October 2016 (two days after its closest approach to the Earth) by the
University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount
Lemmon in the Catalina Mountains north of Tucson. The designation 2016 UD
implies that the asteroid was the fourth object (object D) discovered in the second half of October 2016 (period 2016 U).
2016 UD has a 695 day orbital period and an elliptical orbit tilted at an angle of 10.3° to the plain of the Solar System that takes it from 0.51 AU from the Sun (i.e. 51% of the average distance at which the Earth orbits the Sun, between the orbits of Mercury and Venus) to 2.56 AU from the Sun (i.e. 256% of the average distance at which the Earth orbits the Sun, almost twice the distance at which the planet Mars orbits the Sun). 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 2016 UD has occasional close encounters with the Earth, with the next predicted for June 2174.
See also...
Asteroid 2016 TO11 passes the Earth. Asteroid
2016 TO11 passed by the Earth at a distance of 895 500 km (2.33 times the
average distance between the Earth and the Moon, 0.60% of the average distance
between the Earth and the Sun), slightly after 7.00 pm GMT on Wednesday 12...
Asteroid (462959) 2011 DU passes the Earth. 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%...
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...
2016 UD has a 695 day orbital period and an elliptical orbit tilted at an angle of 10.3° to the plain of the Solar System that takes it from 0.51 AU from the Sun (i.e. 51% of the average distance at which the Earth orbits the Sun, between the orbits of Mercury and Venus) to 2.56 AU from the Sun (i.e. 256% of the average distance at which the Earth orbits the Sun, almost twice the distance at which the planet Mars orbits the Sun). 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 2016 UD has occasional close encounters with the Earth, with the next predicted for June 2174.
See also...
Asteroid 2016 TO11 passes the Earth. Asteroid
2016 TO11 passed by the Earth at a distance of 895 500 km (2.33 times the
average distance between the Earth and the Moon, 0.60% of the average distance
between the Earth and the Sun), slightly after 7.00 pm GMT on Wednesday 12...Asteroid (462959) 2011 DU passes the Earth. 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%...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...
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