ESA keeps tracks of upcoming asteroids close approaches of earth. It is good fun to play around with the visualizer on ESA official web page and also a little scary :-). The next really close encounter is the asteroid 2018VP1 which will pass in a distance of 62397 km or 0.000417 astronomical unit which seems a lot closer ;-). You can view the list here. ESA keeps track of 876710 asteroids so far adding new objects every day.