Most giant moon of Saturn and the second biggest moon in our solar system after Ganymede (Jupiter's Moon), with a diameter of 3,200 miles (5,149.4 kilometers) and 1.8 times bigger than our moon. Titan was discovered on 25 March 1655 by Dutch astronomer Christiaan Huygens and 300 years later, in 1944 when Dutch-American astronomer Gerard Kuiper discovered one of the characteristics that make Titan exceptional: this distant moon has an atmosphere.
Image Source- images.newscientist.com
In the solar system "Titan" is the only moon which has a dense atmosphere and has standing bodies of liquid, including rivers, lakes, and seas, on its surface. Like Earth. Its atmosphere is primarily made of nitrogen and a small amount of methane. This is the only world that has a cycle of liquids raining from clouds, flowing across its surface, filling lakes and seas, and evaporating back into the sky (akin to Earth’s water cycle) and might have a subsurface of an ocean of water.
Image Source- https://www.researchgate.net
This massive moon has a radius of 1600 miles (2,575 kilometers) and is nearly 50 percent wider than Earth's moon. Titan is about 759,000 miles (1.2 million kilometers) from Saturn and about 886 million miles (1.4 billion kilometers) from the sun. Because of the distance, sunlight takes 80 minutes to reach titan and this is why sunlight is 100 times fainter at Titan.
It takes 15 days and 22 hours to complete one orbit of Saturn and Titan is also tidally locked in synchronous rotation with Saturn, like Earth's Moon.
Saturn itself takes 29 Earth years to complete one orbit of the sun( a Saturnian year). Saturn's axis of rotation is also tilted like Earth's, Which results in seasons. But due to the long period of years, it's one season last for seven Earth years to complete. Titan seasons are also aligned with Saturn's seasons because of roughly alignment with Saturn's equatorial plane and its tilt relative to the sun is about the same schedule as Saturn.
Image Credit- https://solarsystem.nasa.gov
On the basis of Cassini-Huygen's mission, Titan is made up mainly of five layers, The innermost layer is a core rock about 2,500 miles (4,000 kilometers) in diameter, surrounded by a shell of water ice (a special type called ice-6 that is only found at extremely high-pressure) and this layer is covered by high-pressure of salty liquid water and after that a layer of a crust of water ice. This surface is coated with organic molecules that have rained or otherwise settled out of the atmosphere in the form of sands and liquids. The surface has a dense atmosphere.
Titan's surface is most like Earth's surface but it has a temperature of -290 degrees Fahrenheit or - 179 degrees Celsius where water ice plays the role of rock, scientist believe that Titan may have volcanic activities but with a liquid of water instead of "lava" of molten rock. Its surface is mainly a composite of methane and ethane which makes river channels and fills great lakes with liquid natural gas.
Image Credit- https://www.astronomy.com
More than 150 moons live in our solar system but only Titan uniquely has a thick atmosphere and has 60 percent greater atmospheric pressure than on Earth which equals to a person would feel swimming about 50 feet (15 meters) below the surface in the ocean on Earth.
Image Source- https://en.wikipedia.org
The numerous gravity measurements of Titan by the Cassini spacecraft revealed that it is hiding an underground ocean of liquid water likely mixed with salts and ammonia. This makes a strong potential it can have a habitable environment and it also has lakes, rivers, and seas of liquid methane and ethane which allow a habitable atmosphere which makes a possibility of life like Earth. But its complex chemistry and unique environments are certain to make it a destination for continued exploration.