DANGER ZONE Pictured above: the orbits of the over 1,000 known Potentially Hazardous Asteroids, or PHA’s. These documented tumbling boulders of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth — about 20 times the distance to the Moon. Although none of them will strike the Earth in the next 100 years, not all PHA’s have been detected — and many of their orbits can become hard to predict. Time for some ion cannons, methinks. (Photo and caption via NASA APOD)
(via inothernews)
