How Earth-Like Planets Work

Since the Kepler telescope went online, astronomers have found there may be an estimate 40 billion planets like Earth in the Milky Way galaxy alone. What does it take for a planet to be considered Earth-like?

How Mars Works

Sure today Mars would kill you with its thin, toxic atmosphere and cold desert temperature swings of 100 degrees, but early on it and Earth were practically twins. Find out how the two planets diverged and if there might be life on the Red Planet.