PHA

Abbreviation: Potentially Hazardous Asteroid. An asteroid is classified as potentially hazardous if it meets the following criteria:

• The distance between the point where the asteroid’s orbit intersects the Earth’s orbit is less than 0.05 AU (about 19.5 LD or 4,600,000 miles).
• The diameter of the asteroid is at least 100-150 meters.

As of 2017 there are 1,786 asteroids that meet the definition.