Saturn's Unique Moon: Iapetus

I always found the solar system to be something of great interest for myself. Therefore, when I found the article "Solving a Tonal Mystery in Orbit Around Saturn" in the New York Times, I decided to post something about it on this Earth Science blog.





Ever since Iapetus (one of Saturn's several moons) was discovered in 1671 by Giovanni Cassini, it has been a mystery. The mystery that always remained until just recently was the appearance of Iapetus. Iapetus appeared to have a surface that consisted of two totally different tones- one dark and one light. A picture from the article that was taken back in September of 2007 is shown on the left.

This solar mystery is probably one of the oldest. And for the longest time, scientists believed that the darker shaded areas of the moon were a result of dust that lands on this moon while in orbit around the planet. They also believed the dust came from one of Saturn's other moons that were also in orbit.

However, recent studies and experiments have caused scientists to redirect their thinking when it comes to figuring out the cause of the two-toned Saturn moon. Recently, scientists have decided not to base Iapetus's appearance soley on the dust theory dealing with its orbit. Instead, they've come up with a theory regaurding the moon's rotation on its axis.

Iapetus has a significantly slow rotation that takes up to eighty Earth days. With this slow rotation, the sun is able to warm areas of water ice into water vapor. this wate vapor than migrates to other locations on the moon. When this wator vapor reaches areas that are much colder (because they are in avoidance of the Sun), the water vapor freezes once again into ice. Therefore, the areas that are shaded in bright color are the areas in which more ice has been formed, whereas, areas that darker in appearance are those areas in which ice has been evaporated and transferred somewhere else.

I feel as if scientists can learn a lot more about the solar system as a whole after figuring out this long lasting mystery. After reading this article, I begin to wonder what other effects are caused by the tilt of a moon or planet.