Potentially dangerous asteroids could wipe out major city says ex-astronaut 1

Potentially dangerous asteroids could wipe out major city says ex-astronaut

This NASA graphic shows the orbits of all the known Potentially Hazardous Asteroids (PHAs), numbering over 1,400 as of early 2013.
This NASA graphic shows the orbits of all the known Potentially Hazardous Asteroids (PHAs), numbering over 1,400 as of early 2013.
Photo Credit: NASA/JPL-Caltech