Red Planet Inhabitants Face Constant Turmoil in 'Mars' Episode 2

In the second episode of National Geographic's "Mars" Season 2, airing tonight (Nov. 19), the inhabitants of Olympus Town grapple with personal turmoil as well as the harsh realities of sharing Mars with a private, profit-driven enterprise.

What Is a Spiral Galaxy?

A spiral galaxy has a distinct winding shape. Most of the galaxies observed by astronomers are spiral galaxies.

Pegasus, the Flying Horse, Marks Mid-Autumn Skies

Step outside this week between 6 and 8 p.m. local time and look overhead and toward the south to see one of the landmarks of the mid-autumn sky: the Great Square of Pegasus, the flying horse.