Asteroid 2019 EW1 passed by the Earth at a distance of about 611 260 km (1.59 times the average distance between the Earth and the Moon, or 0.41% of the distance between the Earth and the Sun), slightly after 2.05 am GMT on Monday 11 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 EW1 has an estimated equivalent diameter of 7-23 m (i.e. it is estimated that a spherical object with the same volume would be 7-23 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 37 and 20 km above the ground, with only fragmentary material reaching the Earth's surface.
2019 EW1 was discovered on 9 March 2019 by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2019 BU1 implies that it was the 46th asteroid (asteroid W1 - 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 W1 = 22 + 24 = 46) discovered in the first half of March 2019 (period 2019 E).
2019 EW1 has a 344 day orbital period, with an elliptical orbit tilted at an angle of 7.21° to the plain of the Solar System which takes in to 0.63 AU from the Sun (63% of the distance at which the Earth orbits the Sun, and slightly less than the distance at which Venus orbits the Sun) and out to 1.29 AU (29% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in 18 May lat year (2018) and the next predicted in February next year (2020). Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2019 EW1 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. This also means that the asteroid has occasional close encounters with the planet Venus, with the last calculated to have occurred in September 2013, and the next predicted for November 2027.
Follow Sciency Thoughts on Facebook.