Monday 30 March 2020

Asteroid 2020 FX4 passes the Earth.

Asteroid 2020 FX4 passed by the Earth at a distance of about 18 206 000 km (47.4 times the average distance between the Earth and the Moon, or 12.2% of the distance between the Earth and the Sun), slightly after 0.10 am GMT on Wednesday 25 March 2020. There was no danger of the asteroid hitting us, though were it to do so it would have presented a considerable threat. 2020 FX4 has an estimated equivalent diameter of 88-280 m (i.e. it is estimated that a spherical object with the same volume would be 88-280 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 60 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater over 4 km in diameter and devastation on a global scale, as well as climatic effects that would last years or even decades.

The calculated orbit of 2020 FX4. JPL Small Body Database.
  
2020 FX4 was discovered on 24 March 2020 (the day before its closest encounter with the Earth) by the University of Hawaii's PANSTARRS telescope. The designation 2012 DJ61 implies that it was the 119th asteroid (asteroid X4 - 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 X4 = 23 + (24 X 4) = 119) discovered in the second half of March 2020 (period 2020 F).

2020 FX4 has a 1389 day (3.80 year) orbital period, with an elliptical orbit tilted at an angle of 9.88° to the plain of the Solar System which takes in to 0.97 AU from the Sun (97% of the distance at which the Earth orbits the Sun) and out to 3.90 AU (3.9% of the distance at which the Earth orbits the sun and more than twice as from the Sun as the planet Mars). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in April 2001 and the next predicted in March 2043. 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, 2020 FX4 is also classified as a Potentially Hazardous Asteroid.
 
See also...
 
https://sciencythoughts.blogspot.com/2020/03/asteroid-2020-fp5-passes-earth.htmlhttps://sciencythoughts.blogspot.com/2020/03/asteroid-2000-bo28-passes-earth.html
https://sciencythoughts.blogspot.com/2020/03/asteroid-2020-fd-passes-earth.htmlhttps://sciencythoughts.blogspot.com/2020/03/asteroid-2020-fc2-passes-earth.html
https://sciencythoughts.blogspot.com/2020/03/asteroid-2004-re84-passes-earth.htmlhttps://sciencythoughts.blogspot.com/2020/03/asteroid-531060-2012-dj61-passes-earth.html
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