Even casual observers are gobsmacked by a first glimpse of the rings of Saturn. But keen-eyed beginners will notice a prominent orange “star” near Saturn which follows the planet from night to night. This is no star… it’s Saturn’s largest moon, Titan, one of the largest moons in the solar system and the only moon with a thick atmosphere…
By far the largest of Saturn’s moons, Titan makes up nearly 96% of the mass of all bodies orbiting Saturn, including the rings. Titan ranks as the second-largest moon in the solar system after Jupiter’s Ganymede, with twice the mass of Earths’ moon. Titan is larger than the planet Mercury.
Titan is also the only Moon with a substantial atmosphere, which is made mostly of nitrogen along with traces of methane and other organic molecules. Titan has lakes of liquid hydrocarbons and hills and dunes and boulders of frozen water (see image above). The presence of organic molecules suggests Titan may have the right chemistry for simple forms of life to develop, so planetary scientists intensely study this massive moon.
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For us backyard observers, Titan presents an easier target than Saturn’s rings. You can see this big moon with binoculars, while the rings are visible only in telescopes. In a larger scope, some observers can even resolve Titan into a tiny orange disk… a tantalizing glimpse of this distant, icy world.
While Titan is the biggest of Saturn’s satellites, the planet has some 62 moons with confirmed orbits. Of this large collection, nine were discovered with telescopes before the age of spaceflight. They are, in increasing distance from Saturn: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, and Phoebe. The moons were named after the Titans of ancient Greek legend.
With a 6″ or 8″ telescope, you can see as many as five of Saturn’s moons– Titan, Enceladus, Dione, Tethys, and Rhea. The moons move from night to night, much like Jupiter’s moons, so they are tricky to track. Sky & Telescope publishes a free Javascript utility to help you sort out which moon is which. You can find it here…