In recent years, astronomers have broadened their search for habitable planets to include previously ignored stars like M-dwarves.

How do we know that a meteor caused the extinction of the dinosaurs?

Caltech astronomer Michael Brown has proposed the existence of a ninth planet, the existence of which would explain the strange orbits of six KBOs. 

Einstein's groundbreaking theory of general relativity has remained an essential hallmark of modern physics.

We now know there's liquid water on Mars, according to NASA. But at the turn of the 20th century, we believed something else: that Mars had canals.

How buckyballs fit into the formation of new stars.