Michelle Nichols from the Adler Planetarium explains why scientists were blindsided by the “city-killer” asteroid that just passed Earth

This illustration provided by NASA depicts the OSIRIS-REx spacecraft and the Earth. On Friday, Sept. 22, 2017, the probe will use Earth's gravity to put it on a path toward the asteroid Bennu. (Conceptual Image Lab/Goddard Space Flight Center/NASA via AP)

On July 25th, Asteroid 2019 OK, measuring 57 to 130 meters wide (187 to 427 feet), got really close to Earth. Bill and Wendy speak to Michelle Nichols, Director of Public Observing at the Adler Planetarium, to talk about why the ‘city-killer’ asteroid went undetected for so long, how many near-earth asteroids have been discovered so far, how NASA would handle a “killer” asteroid, why faking the moon landing was impossible, and more.

You can find Bill and Wendy on Twitter,  Facebook, and Instagram. The Bill and Wendy Show airs Monday through Friday from 10 a.m. to noon, then streaming on WGN Extra from noon to 1 p.m.

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