Examination of Mimas, the closest of Saturn's regular moons, has shown that it has a subtle wobble that is a greater surface displacement than expected. Researchers suggest that it means that the icy surface of the moon hides either a rugby-ball shaped rocky core, or a sub-surface ocean.
Using instruments aboard the Cassini spacecraft to measure the wobbles of Mimas, the closest of Saturn’s regular moons, a Cornell University astronomer publishing in Science, Oct. 17, has inferred that this small moon’s icy surface cloaks either a rugby ball-shaped rocky core or a sloshing sub-surface ocean.
“After carefully examining Mimas, we found it librates – that is, it subtly wobbles – around the moon’s polar axis,” Radwan Tajeddine, Cornell research associate in astronomy and lead author of the article. “In physical terms, the back-and-forth wobble should produce about 3 kilometers of surface displacement. Instead we observed an unexpected 6 kilometers of surface displacement,” he said.
“We’re very excited about this measurement because it may indicate much about the satellite’s insides. Nature is essentially allowing us to do the same thing that a child does when she shakes a wrapped gift in hopes of figuring out what’s hidden inside,” Tajeddine said.
The astronomy team used a technique called stereo-photogrammetry to interpret images taken by the Cassini Imaging Science Subsystem to measure the libration. In this technique, astronomers employ Cassini photographs of Mimas taken at different times and from various vantage points to build precise 3-D computer models of the locations of hundreds of surface reference points. From these, the researchers determined the moon’s shape and were able to notice that the satellite didn’t rotate smoothly but rocked back and forth a bit as well.
(Score: 2) by aristarchus on Wednesday October 22 2014, @06:49AM
The most amazing thing about Mimas is that it was really discovered after the Star Wars movies, even though it looks uncannily similar to the Death Star! (Remember to reverse you memes at this point, we are entering actual science: "That's no Death Star, it's a moon!" See how that works, in reverse?) But it is even cooler to imagine that the interior of the moon may actually be liquid! I don't know why, but it is cool.
(Score: 2) by monster on Thursday October 23 2014, @10:52AM
Just for clarification, Mimas [wikipedia.org] wasn't discovered after the Star Wars movie, it had been in 1789. It was the Herschel crater (the "superlaser") what was discovered.
(Score: 2) by aristarchus on Saturday October 25 2014, @12:31AM
Ah, yes, right! Thanks for the correction.
(Score: 1) by Valkor on Wednesday October 22 2014, @06:58AM
(Score: 2) by aristarchus on Wednesday October 22 2014, @07:27AM
See Europa Report before you go off the deep end. As a recall, early in the film they had footage of Neil de Grasse Tyson saying that he would love to go ice fishing on Europa. Well, maybe. In the movie, things do not end very well. SunTzu: know yourself and not know your enemy, and it's a 50/50 deal.
(Score: 2) by sudo rm -rf on Wednesday October 22 2014, @11:57AM