Planetary Defense

Science & Astronomy

Apophis is a near-Earth asteroid whose orbit brings it within about one-twentieth of the distance to the Moon, making its trajectory one of the best tracked in planetary defense...

space-science

A new crater on the Moon forms when an asteroid or comet fragment strikes the surface at high speed, excavating a bowl-shaped hole in a single, brief event. Unlike erosion on Ea...

Planetary Science

Asteroid Apophis is a near-Earth object whose close approaches draw public attention, yet its actual dimensions and physical properties are well documented through radar and opt...

space-astronomy

Apophis is a near-Earth asteroid whose close approaches have drawn public attention, yet it is not an extinction-level threat. This profile explains what Apophis is, how its orb...