Take a facts-based journey through the universe with the Astronomy Cast. This episode explores the impact our moons, Sun and placement in the Milky Way have on our planet and the evolution of life on our planet. But what if things were different? What would be the implications?
CREDIT: TONY and DAPHNE HALLAS/SCIENCE PHOTO LIBRARY Andromeda galaxy. Optical image of the Andromeda spiral galaxy (M31).