From The New York Times:
This week, two asteroids — one big enough to destroy a city, and the other so large it could end civilization — are set to fly near our planet.
Don’t panic. Both have a zero percent chance of impacting Earth. And, depending on where you are in the world, you may even be able to see one of them. The bigger of the pair, (415029) 2011 UL21, will travel at a distance more than 17 times farther away than the moon on Thursday at 4:14 p.m. Eastern time. It is a whopping 7,600 feet long, but it will be too far to spot easily without a strong telescope. However, two days later, the smaller space rock, named 2024 MK will get considerably nearer to humanity.