Tunguska-Size Asteroid Makes Surprise Flyby Of Earth. Comes Within Half The Distance To Moon

Tunguska-Size Asteroid Makes Surprise Flyby Of Earth. 
Asteroid "2018 GE 3" came within half the distance separating the earth from the moon whose average distance from our planet is the equivalent of 48 round trips between San Francisco and Washington D.C. Another useful perspective is to note that the asteroid came within 10 earth diameters of "the third stone from the sun."

http://www.space.com/40315-asteroid-2018-ge3-surprise-flyby.html

Quora: Which Is The Most Mysterious Event That Ever Happened?
See the reply by Puneet Bansal, Director of Forecasting and Strategy at DRG Group 
https://www.quora.com/Which-is-the-most-mysterious-event-that-ever-happened