Asteroid 2020 JB1 passed by the Earth at a distance of about 857 900 km (2.23 times the average distance between the Earth and the Moon, or 0.57% of the distance between the Earth and the Sun), at about 6.40 am GMT on Sunday 10 May 2020. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2020 JB1 has an estimated equivalent diameter of 9-30 m (i.e. it is estimated that a spherical object with the same volume would be 9-30 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 33 and 16 km above the ground, with only fragmentary material reaching the Earth's surface.
2020 JB1 was discovered on 13 May 2020 (three days after its closest approach to the Earth) by the Atlas MLO Telescope at Mauna Loa Observatory in Hawaii. The designation 2020 JB1 implies that the asteroid was the 26th object (object B1 - in numbering asteroids the letters A-Z, 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 B1 = 24 + 2 = 6) discovered in the first half of May 2020 (period 2020 J).
2020 JB1 has a 474 day (1.30 year) orbital period and an eccentric orbit tilted at an angle of 1.01° to the plane of the Solar System, which takes it from 0.75 AU from the Sun (i.e. 75% of he average distance at which the Earth orbits the Sun) to 1.62 AU from the Sun (i.e. 162% of the average distance at which the Earth orbits the Sun, and more than 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 2020 JB1 has occassional close encounters with the Earth, with the last having happened in May 2010, and the next predicted in July 2024. The asteroid also has occassional close encounters with the planet Mars, with the next predicted in June 2050.
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