Asteroid (504800) 2010 CO1 passed by the Earth at a distance of about 5 327 000 km (13.9 times the average distance between the Earth and the Moon, or 3.56% of the distance between the Earth and the Sun), slightly after 3.40 am GMT on Saturday 14 September 2019. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. (504800) 2010 CO1 has an estimated equivalent diameter of 82-260 m (i.e. it is estimated that a spherical object with the same volume would be 82-260 m in diameter), and an object at the upper end of this range would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be about 60 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater about 4 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.
(504800) 2010 CO1 was discovered on 31 January 2010 by the NEOWISE system on the Wide-field Infrared Survey Explorer satellite. The designation (504800) 2010 CO1 implies that it was the 38th asteroid (asteroid O1 - in numbering asteroids the letters A-Y, excluding I, are assigned numbers from 1 to 24, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 25, A2 = 49, etc., which means that O1 = 14 + (24 X 1) = 38) discovered in the sixth and seventh weeks of 2010 (period 2010 C), while the designation 504800 implies that it was 5048 00th asteroid ever discovered (asteroids are not given this longer designation immediately to avoid naming double or false sightings).
(504800) 2010 CO1 has a 372 day orbital period and an eccentric orbit tilted at an angle of 24.0° to the plane of the Solar System, which takes it from 0.79 AU from the Sun (i.e. 79% of he average distance at which the Earth orbits the Sun) to 1.23 AU from the Sun (i.e. 123% of the average distance at which the Earth 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 close encounters between the asteroid and Earth are common, with the last having occurred in September 2018 and the next predicted in September 2020. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, (504800) 2010 CO1 is also classified as a Potentially Hazardous Asteroid.
Follow Sciency Thoughts on Facebook.