Year of the Solar System, February 2011: Small Bodies – Big Impacts
Source: NASA
Excerpt: There are many types of small bodies in the solar system, but none may be as dramatic as comets. …Comets also have a big influence when they collide with Earth. …Some scientists argue that colliding comets early in Earth's development contributed much of Earth's water. Some scientists also postulate that comets could have delivered organic molecules critical to the formation of life....