Saturn’s largest moon, Titan, also will fall under Webb’s powerful gaze. Titan is unique because it is the only moon in our solar system with a substantial atmosphere. In fact, it’s bigger than the planet Mercury. The atmospheric pressure on Titan is about 50% greater than on Earth. Like Earth, that atmosphere is mostly nitrogen, but Titan also has vaporous hydrocarbons like methane. Titan also is much colder than Earth, with a surface temperature around minus 290° Fahrenheit (minus 180°…