January 20, 2022
Titan (or Saturn VI) is the largest moon on the planet Saturn. It is the only known natural satellite in our solar system that has atmosphere, and the only known object outside the earth with stable bodies of liquids on the surface. Titan is the sixth ellipsoidal (true moon) from Saturn. It is planet-like, has a diameter that is about 50% larger than the Earth's moon and has about 80% more mass. By diameter, it is the second largest in the solar system, after Jupiter's moon Ganymede. In volume, it is larger than the smallest planet, Mercury, even though it is only half as massive. Titan became the first known moon of Saturn at the discovery made by the Dutch astronomer Christiaan Huygens in 1655, and the fifth moon discovered around a planet other than Earth (the first four were the Galilean moons around Jupiter discovered in 1610). Titan consists primarily of ice and rocks. As with Venus, the dense, opaque atmosphere made it difficult to understand the surface of Titan before the space age. In 2004, the Cassini-Huygens spacecraft arrived, collected new data and discovered floating lakes of hydrocarbons at the polar regions. The landing craft Huygens landed on solid ground 14 January 2005. The surface is geologically young; although rocks and several possible cryovolcanoes have been discovered, the surface is slippery and few impact craters have been found. Titan's atmosphere consists largely of nitrogen - smaller components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. The climate - including wind and rain - forms surface formations, including dunes, rivers, lakes and oceans (probably of liquid methane and ethane) and deltas. They are governed by the weather patterns of the seasons, as it were on earth. The liquids (both on and below the surface) and the robust nitrogen atmosphere mean that Titan's methane cycle is considered an analogue to the Earth's water cycle, but with a much lower temperature. The satellite is believed to contain microbial life or, at the very least, a prebiotic environment rich in complex organic chemistry with a possible subterranean ocean acting as a biotic environment.