Nasa to land on asteroid after one nearly clobbers us

Astronomers shared a collective sigh of relief last week when a 100-foot asteroid hurtling toward Earth missed by 50,000 miles—just a fifth of the distance to the moon.

As comforting as the avoided terrestrial calamity was, what remains disturbing is that no one knew it was coming.

The near miss came just days before Nasa plans to launch an $800 million probe that will land on a much larger asteroid, a remnant from the beginning of the solar system that should provide clues to Earth’s origins.