Apollo 8 astronauts discuss their historic flight at the Newseum as the flight's 40th anniversary approaches.

Celebrating the 40th anniversary of Apollo 8, astronauts Frank Borman, James Lovell and William Anders discuss the flight.

Celebrating the 40th anniversary of Apollo 8, astronauts Frank Borman, James Lovell and William Anders discuss the flight. Part 2 of 3

Celebrating the 40th anniversary of Apollo 8, astronauts Frank Borman, James Lovell and William Anders discuss the flight. They are introduced by Senator John Glenn

The Universe is a black void, with a scattering of stars, nebulae and galaxies – or so it appears to observers using visible light. But if we include other forms of radiation invisible to us, the picture changes completely...

Athabasca Valles is a young 'outflow' channel system in the equatorial region of Mars. Most researchers agree that it was carved by catastrophic floods of water, and some believe that frozen floodwaters survive to this day on the channel floor.

STS-126 Spacewalkers at Work - 11/22/08 - Astronauts Heidemarie Stefanyshyn-Piper and Steve Bowen work on the starboard solar alpha rotary joint during the third STS-126 spacewalk.

Second Spacewalk for STS-126- 11/20/08 - Astronauts Heidemarie Stefanyshyn-Piper and Shane Kimbrough tackle the second spacewalk of the STS-126 mission.

STS-126 EVA 1 - Astronauts perform first spacewalk on the STS-126 mission.

Using a piece of transparent plastic and some tape, STS-126 Mission Specialist Don Pettit Builds a Coffee Cup that works in a weightless environment.