>> Our planet's near miss with an asteroid the size of a school bus on Thursday was used to test an early warning system after a similarly sized object wreaked havoc in Russia four years ago. 2012 TC4 named for the year was discovered, was never thought to be in actual risk of collision, but it did pass within 27,000 miles of the Earth.
That's really close. Just a tad further than some satellites in orbit, seen here tracked by an observatory in Japan. The European Space Agency says the early warning system, an international but volunteer effort, came back with mixed results, because one of its radar arrays in Puerto Rico was damaged in Hurricane Maria.
Over 1,000 people were injured in 2013 when an object of around 20 meters in size exploded over Siberia. If it had hit a more populated area, the damage could have been catastrophic.