Just when we think we understand a little bit about our neck of the cosmic woods, something comes up that whacks us upside the head (in a nice way) and spurs lots of questions.
Take the planet Saturn, for example. We’ve all grown up being taught that this planet is a gas giant—made mostly of hydrogen gas, with varying amounts of helium, ammonia, nitrogen, methane, and other gases in its atmosphere. We’ve studied that atmosphere, charting storms that churn through it, and measuring temperature and wind speed variations. Heavy atmosphere, lots of round or semi-round storms in it, fast winds, and steadily thickening layers as you go down toward the core: that’s what we pegged for Saturn.
Still, the nature of planetary science is to study planets—and keep studying them for long periods of time. Planets aren’t static places, not even the “deadest” of them. Not by any means. They change over time, develop new features on their surfaces or in their atmosphees. And, their visible appearances don’t always tell us the full story. Just look at Saturn with infrared eyes, sensitive to thermal radiation (heat), for example, and interesting features pop right into view.
There’s this bizarre, six-sided feature that encircles the North Pole of the planet near 78 degrees north latitude, for example. It was actually discovered back in the 1980s by the Voyager spacecraft missions, but this is the first time we’ve been able to position a spacecraft (Cassini) in a good orbit to get a clear image of the thing. You can read more about the specifics of the image here, but suffice to say, this is the best view we’ve had of this atmospheric phenomenon ever. The hexagon of clouds is long-lived, so we’ll have much more time to study it (at least as long as Cassini pipes images and data back). But what is it? There’s nothing been seen like it at any other planet in our solar system, and nobody expected to see anything like it in Saturn’s thick atmosphere, either. It’s naturally occurring, so now the trick is to come up with a good atmospheric model that can explain the thing. There is a similar type of atmospheric phenomenon on Earth, called the polar vortex, so perhaps using that as a model, astronomers will be able to get a handle on Saturn’s, which is four times the size of Earth.
I remember when Saturn used to be thought strange because it had rings. Now, it turns out that Jupiter, Uranus, and Neptune have rings. And, in the distant past, Earth might have had one, too. What else will we learn about our solar system before we think we can say we know it all??