A 54-pound meteorite from Mars is expected to fetch up to $4 million when it goes up for auction later this month at Sotheby's.

As it flew by Mars, the spacecraft's onboard camera snapped 22 pictures of the planet's surface, sending them back home to Earth – the first-ever close-up photos of Mars obtained by humans, and the very first photos of another planet obtained from a position in deep space.

Compare Mars and Earth in size, atmosphere, gravity, and potential for life. Discover their differences and shared traits. Explore the mysteries of the Red Planet!

Mariner 4, built by JPL in Pasadena, took the images on July 14, 1965. One of the mission's leaders reflects on decades of studying the Red Planet.

A new map shows hidden Martian rivers stretching thousands of miles, offering fresh evidence of a warm, wet ancient Mars.

New discoveries by NASA's Curiosity Mars rover may not only explain why the Red Planet is a dry, lifeless desert, but that it may have been on an inevitable path to being a dead world despite being so similar to Earth.