Moons Of Saturn, Uranus, & Neptune

Titan: What lies beneath the smog?

Titan

Unlike most other moons in our solar system, Titan has a very thick atmosphere that hides its surface from view. Chemicals in the atmosphere give Titan its reddish color.

Titan's atmospheric composition:

• 90% nitrogen
• 10% mixture of argon, methane, ethane and other hydrogen compounds

Despite its distance from the Sun, Titan's surface temperature is slightly warmer than it otherwise would be due to the greenhouse effect. This is the same process that traps heat on Earth. Some scientists believe Titan's current environmental status may be similar to that of Earth's before life formed.

During the formation of the solar system, Titan formed past the frost line where temperatures in the solar nebula were cold enough for methane, ammonia and water to condense into ice. Titan is composed mostly of ices, including methane and ammonia ice. Some of this ice sublimated long ago to form an atmosphere on Titan. Over billions of years, solar ultraviolet light broke apart the ammonia molecules into nitrogen and hydrogen. The lighter hydrogen escaped from the atmosphere but the heavier nitrogen molecules remained and accumulated to give Titan its nitrogen atmosphere. SHOW METHE MATH

Titan was recently visited by the Huygens probe, which landed successfully on the moon's mountainous surface after being released from the Cassini spacecraft in 2004. The Huygens probe sent back the first real images of Titan's mysterious surface, and scientists are still analyzing the data.

Saturn's Medium-Size Moons

Saturn's Medium-Size Moons(300 — 1,500 km in diameter)

Saturn has 6 medium-size moons. In order of increasing distance from the planet, they are:

• Mimas
• Enceladus
• Tethys
• Dione
• Rhea
• Iapetus

All are heavily cratered, indicating generally ancient surfaces, but each shows evidence of past geological activity. The geological activity may seem surprising when we consider how small these moons are; all are considerably smaller than the Galilean moons. Enceladus, with its grooved terrain, is barely 500 km across (small enough to fit inside Colorado). In fact, the geological activity is probably a demonstration of the effectiveness of low temperature icy geology. Icy combinations of water, ammonia and methane can melt, deform and flow at remarkably low temperatures, producing a variety of volcanic and tectonic features.

The surface of Enceladus shows signs of intense recent geologic activity. The Cassini spacecraft passed by the moon in 2005 and returned images showing ice geysers erupting from the surface. The material spewed out from these eruptions is a primary cause of Saturn's E-ring.

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