In conjunction with the first total solar eclipse in the continental U.S. in 99 years, Science Channel celebrates by presenting a definitive series on Earth's closest neighbors in the solar system. Former NASA astronaut Mike Massimino hosts, guiding viewers through hourlong episodes that detail Venus, Mars, the newly discovered Planet 9, Exoplanets and more. A best-selling author, Massimino is a veteran of two missions in the Hubble Space Telescope and four space walks. He's also credited as the first person to tweet from space.