Asteroids are just boring hunks of space rock, right? Well, you might have thought so. But you would be wrong. Well… Mostly wrong. Some of them are rather interesting.
This particular interesting hunk of space rock is 10199 Chariklo, and it’s an asteroid with a ring system! Chariklo is a Centaur – that is, an asteroid which dwells amid the orbits of the gas giants. This one has an orbit which is very close to the orbit of Uranus. It has a diameter of roughly 232 km, it’s listed as a “possible dwarf planet”, and it may have water ice on its surface.
The ring system is a surprise though. It was discovered just a few days ago, as the asteroid passed in front of background stars. As stars are covered and uncovered by a planetary ring system, their light dims briefly as they’re occulted by the dusty material which makes up the ring. As all four of our solar system’s gas giants have rings of their own, this is a pretty well known technique. Saturn’s faint outer rings have been observed this way before. But finding two rings – named Oiapoque and Chuí for two of Brazil’s most well known rivers – orbiting an asteroid? Actually, that raises a few interesting questions.
There’s a lot about planetary rings which we’re not really certain about. How exactly do they form? How long do they last? What kinds of ring systems are possible? From our solar system, we can assume that they must form quite readily around gas giants, and we’ve detected a vast ring system around one exoplanet. Apparently, size is not a prerequisite though. If tiny Chariklo can hold on to a ring system, then it’s likely that any of the objects in the solar system could.
Suddenly, those pretty images of what Earth’s scenery might look like if our planet had rings don’t seem quite so far fetched. Then again, for all we know, maybe Earth did once have rings – at least, before they formed into the Moon.
Image credit: Lucie Maquet