Asteroid 2019 FB passed by the Earth at a distance of about 1 142 400 km (2.98 times the average distance between the Earth and the Moon, or 0.76% of the distance between the Earth and the Sun), at about 4.05 am GMT on Friday 15 March 2019. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2019 FB has an estimated equivalent diameter of 12-39 m (i.e. it is estimated that a spherical object with the same volume would be 12-39 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 30 and 12 km above the ground, with only fragmentary material reaching the Earth's surface.
2019 FB was discovered on 16 March 2018 (the day after its closest approach to the Earth) by the Atlas MLO Telescope at Mauna Loa Observatory in Hawaii. The designation 2019 FB implies that the asteroid was the second object (object B - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, so that B = 2) discovered in the second half of March 2019 (period 2019 F).
2019 FB has an 1275 day orbital period and an eccentric orbit tilted at an angle of 3.16° to the plane of the Solar System, which takes it from 0.97 AU from the Sun (i.e. 97% of the the average distance at which the Earth orbits the Sun) to 3.63 AU from the Sun (i.e. 363% of the average distance at which the Earth orbits the Sun, or more than twice the distance at which the planet Mars orbits). 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).
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