Titan
Titan was discovered in 1655 by Dutchman Christiaan Huygens. It orbits Saturn. Huygens named it Luna Saturni. When more moons were discovered, it was re-named Saturn II, then IV, then VI, which stuck as the official title, even though there are at least 19 moons in closer orbit of Saturn. It's also been referred to as "Saturn's ordinary satellite," but Titan is anything but ordinary.
Titan is the only body in the solar system, aside from Earth, with stable liquid bodies at its surface* and a dense atmosphere. Its landscape is relatively smooth, although there are mountains. As on Earth, the air is primarily composed of Nitrogen. Methane and Ethane clouds produce rain, wind and weather that give it seasons. It also has subsurface oceans*.
