Orbiting 400 kilometers above Quebec, Canada, planet Earth, the International Space Station Expedition 59 crew captured this snapshot of the broad St. Lawrence River and curiously circular Lake Manicouagan.
on April 11
Right of center, the ring-shaped lake is a modern reservoir within the eroded remnant of an ancient 100 kilometer diameter impact crater. The ancient crater is very conspicuous from orbit, a visible reminder that Earth is vulnerable to rocks from space.
Currently, there is no known asteroid with a significant probability of impacting Earth in the next century. But a fictional scenario to help practice for an asteroid impact is on going at the 2019 IAA Planetary Defense Conference.