Titan (moon)
Saturn's largest moon, with a thick atmosphere and liquid lakes.
Titan, Saturn’s largest moon, is also the second-largest moon in the Solar System. It stands out as the only moon with a thick atmosphere—denser than Earth’s—and, aside from Earth, the only solid body in the Solar System where stable surface liquid has been clearly confirmed. Often called a planet-like moon, Titan has a diameter 48.16% greater than Earth’s moon and is 80% more massive. Although it is bigger than Mercury, Titan is only 40% as massive because Mercury is dense iron and rock, while Titan is mostly less-dense ice.
Discovered in 1655 by Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn and the sixth planetary satellite ever identified (after Earth’s moon and Jupiter’s four Galilean moons). It orbits Saturn at a distance of 20 Saturn radii, or about 1.2 million kilometers above the planet’s visible surface. From Titan’s surface, Saturn—ignoring its rings—spans an angle of 5.09 degrees, making it more than ten times larger in Titan’s sky than Earth’s moon appears from Earth.
Titan is made mostly of ice and rocky material, with a rocky core surrounded by layers of ice, including a crust of ice Ih and a subsurface layer of ammonia-rich liquid water. Before the Cassini–Huygens mission arrived in 2004, its thick, opaque atmosphere hid the surface, much like Venus before the Space Age. That mission revealed liquid hydrocarbon lakes at Titan’s poles and showed that its atmosphere rotates faster than the moon itself. The surface is geologically young and generally smooth, with few impact craters, though mountains and several possible cryovolcanoes have been spotted.
The atmosphere is mostly nitrogen and methane, with trace components that create hydrocarbon clouds and a heavy haze of organonitrogen compounds. Titan’s climate—including wind and rain—shapes Earth-like surface features such as dunes, rivers, lakes, seas (likely of liquid methane and ethane), and deltas, all driven by seasonal weather patterns. Its methane cycle, involving both surface and subsurface liquids, closely mirrors Earth’s water cycle, but at a frigid temperature around 94 K (−179 °C; −290 °F). For these reasons, Titan is often called the most Earth-like object in the Solar System.
**Discovery and naming**
Christiaan Huygens discovered Titan on March 25, 1655.
Quick Facts
- Mpc Name
- Saturn VI
- Adjectives
- Titanian or Titanean (both t · aɪ · ˈ · t · eɪ · n · i · ə · n)
- Named After
- Τῑτάν Tītan
- Discoverer
- Christiaan Huygens
- Discovered
- March 25, 1655
- Satellite Of
- Saturn
- Eccentricity
- 0.0288
Facts from the source article.
Lore & Background
Discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn and the sixth known planetary satellite. Huygens named it Saturni Luna, and later the name Titan was proposed by John Herschel in 1847, after the Titans of Greek mythology. Titan orbits Saturn at 20 Saturn radii, and from its surface Saturn subtends an arc of 5.09 degrees, more than ten times as large as the Moon in Earth's sky. Titan is tidally locked, showing one face to Saturn, and its rotational period equals its orbital period of 15 days and 22 hours. The small moon Hyperion is locked in a 3:4 orbital resonance with Titan.
Reader's Guide
Titan's significance stems from its Earth-like features despite a temperature of about 94 K. Its atmosphere is mainly nitrogen and methane, with hydrocarbon clouds and heavy organonitrogen haze. Its climate creates surface features similar to Earth's, such as dunes, rivers, lakes, seas (probably of liquid methane and ethane), and deltas, dominated by seasonal weather patterns. The Cassini–Huygens mission in 2004 revealed liquid hydrocarbon lakes in the polar regions and atmospheric super-rotation. Titan's methane cycle nearly resembles Earth's water cycle. The moon is primarily composed of ice and rocky material, with a rocky core surrounded by layers of ice, including a subsurface layer of ammonia-rich liquid water. Its geologically young surface is generally smooth, with few impact craters, though mountains and possible cryovolcanoes exist. Titan is sometimes called the most Earth-like celestial object in the Solar System.
Did You Know?
- Titan is the second-largest moon in the Solar System after Jupiter's Ganymede.
- Titan's atmosphere is denser than Earth's.
- Titan has stable bodies of surface liquid, likely methane and ethane.
- Titan was discovered by Christiaan Huygens in 1655.
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