Potentially Hazardous Asteroids

What Makes an Asteroid Potentially Hazardous?

NASA classifies an asteroid as Potentially Hazardous when it meets both of these criteria:

1. Its Earth MOID (Minimum Orbit Intersection Distance) is less than 0.05 AU — roughly 19.5 lunar distances, or about 7.5 million km. This means the asteroid's orbital path comes very close to Earth's orbital path.

2. Its estimated diameter exceeds 140 meters. This threshold is chosen because objects of this size could cause regional to continental devastation on impact — a 140m asteroid hitting land would release energy equivalent to thousands of nuclear weapons.

As of 2026, there are approximately 2,400 known PHAs. None are currently predicted to impact Earth in the foreseeable future. However, their orbits are continuously refined as new observations are made.