Answers to science's most provocative questions.
Scientists explore Pluto from its discovery in 1930 to the New Horizons spacecraft mission due to arrive in 2015.
How the earth's atmosphere came to be; the one man to have braved the atmosphere's upper reaches and survived.
Ice may have entombed Earth for hundreds of millions of years, spawning the complex animals that evolved in the greenhouse heat wave that followed.
The search for the building blocks of life on Mars; an attempt to prove life was, or is, possible on the red planet.
The Cassini-Huygens spacecraft has been sending images and a wealth of scientific revelations from Saturn's orbit since 2004.
