Sand dunes on Earth (top) and dunes on Titan (bottom)

Are tides a peculiarity of our planet? Often, other bodies in our solar system are thought of as static, somewhat boring large rocks that sit around doing nothing. (Ok – they orbit. But what else?)

And yet, when we look at what causes tides, there is no real reason to believe that other planets or satellites should not experience the same phenomenon. Tides on Earth are caused by the Moon’s gravitational pull. Because the Moon is a decent fraction of the Earth’s mass, it is capable of varying the gravitational field we “feel” from the Sun enough to actually make a difference. Water feels the Moon’s field differently than the rest of the crust beneath it, and therefore it is either pulled closer to, or pushed farther away from the Moon, thus creating the effect called tides. Therefore, all that is needed is something that will slightly but significantly alter the main gravitational field on a planet, as well as some sort of fluid that can move around more easily than the  surface beneath it.

So let’s take a look around us. Mars has two satellites, but they are very small and can’t do much of anything. Furthermore, Mars doesn’t really have fluids floating around, there is no atmosphere, and, at least on the surface, no liquid water. One is then inclined to look at the giant gas planets like Saturn and Jupiter—they practically are balls of fluid, and have very large moons. The problem here is that these planets are so large that the moons are minuscule in comparison, and the gravitational field’s variation is minuscule.

Now it’s time to think out of the box: what if a moon, and not a planet, experienced tidal effects? Out of all moons, the one where conditions are perfect for tides is Titan, one of Saturn’s more famous satellites. In fact, when compared to Earth, it’s an even better place to find tides. Titan’s atmosphere is extremely rich and even heavier than Earth’s. Furthermore, even though it does not have a moon of its own, Titan has something better—Saturn. Think of it as the Moon having tides because of effects from the Earth, rather than vice-versa.

The one tricky thing is that Titan, just like our own Moon, is in a locked orbit with Saturn—it is always showing its host planet the same face. (Read more…)