NASA has put together an image showing the orbits of all known
Potentially Hazardous Asteroids
(PHAs) currently threatening Earth. That's 1,400 in total — making this map uncomfortably busy.
To qualify as a PHA, an asteroid needs to be fairly large — at least 460 feet (140 meters) in size — and follow orbits that pass close to the Earth's orbit — within 4.7 million miles (7.5 million kilometers).But a PHA is not necessarily on a collision course with Earth. And in fact, none of these PHAs is considered a threat for the next 100 years. But by continuing to observe and track these asteroids, NASA hopes to refine their orbits so that they can make more precise predictions in the future....MORE, including interactive map.
