If a scary asteroid will actually strike Earth, here's how you'll know

This story, originally published in June 2021, has been republished as part of Mashable's "Space Rocks" series. On April 13, 2029 (which happens to be Friday the 13th), something unsettling will happen. A decent-sized asteroid, the 1,100-foot-wide Apophis, will pass so close to Earth it'll be visible in the sky from certain places. Crucially, the giant rock will not strike our humble planet. But it will pass closer than 20,000 miles from the surface, which is closer than where some of the United...