Earth is rising 384,000 kilometers from the Moon's barren, cratered terrain. Its vast oceans and thick atmosphere make it appear predominantly blue from space. Situated 150 million kilometers from the Sun, the Earth is the only planet in the solar system where conditions allow liquid water to exist at the surface. As a result life has thrived, continually modifying Earth's environment for over three quarters of its 4.6 billion-year history. This photograph was taken during the Apollo 8 mission in December 1968.