Friday 30 October 2020

Asteroid 2000 TU28 passes the Earth.

Asteroid 2000 TU28 passed by the Earth at a distance of about 9 884 000 km (25.7 times the average distance between the Earth and the Moon, or 6.61% of the distance between the Earth and the Sun), at about 4.45 pm GMT on Friday 23 October July 2020. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2000 TU28 has an estimated equivalent diameter of 130-410 m (i.e. it is estimated that a spherical object with the same volume would be 130-410 m in diameter), and an object of this size 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 1800-18 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater roughly 2-7 km in diameter and devastation on a global scale, as well as climatic effects that would last years or even decades.

The closest approach of 2000 TU28 to the Earth on 19 October 2020. JPL Small Body Database.

2000 TU28 was discovered on 3 October 2000 by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research Laboratory in Socorro, New Mexico. The designation 2000 TU28 implies that it was the 692nd asteroid (asteroid U28 - 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 U28 = (24 X 28) + 20 = 692) discovered in the second half of August 2003 (period 2003 Q) while the designation 480936 implies that it was 480 936th asteroid ever discovered (asteroids are not given this longer designation immediately to avoid naming double or false sightings).

The orbit of 2000 TU28, and its current position. JPL Small Body Database. 
2000 TU28 has a 406 day (1.11 year) orbital period, with an elliptical orbit tilted at an angle of 15.6° to the plain of the Solar System which takes in to 0.88 AU from the Sun (88% of the distance at which the Earth orbits the Sun) and out to 1.27 AU (1.27% of the distance at which the Earth orbits the sun). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in April 2012 and the next predicted in June next year (2021). 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). As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2000 TU28 is also classified as a Potentially Hazardous Asteroid.
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