Startup Portola is treating its AI companions like characters in a novel, complete with lore, emotions, and personal lives.

Asteroid Bennu has gone from a dark speck in telescope images to a kind of time capsule, carrying intact chemistry from the ...

A brilliant green fireball racing at roughly 100,000 miles per hour tore across the sky over the United States, flaring into ...

For years, the center of our galaxy has been painted as a place where stars go to meet their end — a region ruled by Sagittarius A*, a black hole so massive that its gravity can stretch, tear, and ...