A house-sized asteroid will fly by Earth on Tuesday, Dec. 13, coming within 1.8 Lunar Distances (LD), or 690,000 kilometers of our planet. The space rock, designated 2016 XW20, was discovered on Dec. 8 by Mount Lemmon Survey. Its closest approach is expected at 00:18 UTC, passing with a velocity of 8.42 km/s.
The asteroid is estimated to be about 21 meters wide, therefore it is similar in size to the meteor that exploded over Chelyabinsk, Russia on Feb. 15, 2013, injuring over 1,000 people. However, 2016 XW20 is not a threat to Earth, as it will pass at a relatively safe distance and is not expected to hit our home planet.
2016 XW20 will also pass at approximately 1.95 LD from the Moon (at 11:55 UTC), one day ahead of its fly-by of Earth.
What is noteworthy, besides 2016 XW20, two other 15-meter-wide asteroids will whizz by Earth on the same day. 2015 XX169 will miss our planet at a distance of 7.5 LD, while 2015 YA at 9.6 LD.
Another significant close approach will take place on Dec. 18, when asteroid 2016 XK18, with an estimated size of about 70 meters, will pass Earth at a safe distance of 5.8 LD.
Currently there are 1,748 potentially hazardous asteroids (PHAs) detected. None of them is on a collision course with our planet, although astronomers are finding new ones all the time.