Category Archives: Saturn’s Moons
At the north pole of Saturn’s largest moon Titan lie the largest (and only known) bodies of surface liquid in the Solar System outside of Earth. But on Titan, where temperatures are regularly around negative 300ºF, the liquid isn’t water but rather methane and ethane: compounds which are found as gases here on Earth. Titan’s seas and lakes are exotic environments that scientists are only just starting to understand, and even with radar imaging by NASA’s Cassini spacecraft there’s a lot we just don’t know about them. But one thing some researchers have managed to figure out using simulated Titan environments in the lab is that these lakes may sometimes fizz with bubbles of nitrogen—potentially explaining some of the mysteries of Cassini’s observations.
“Thanks to this work on nitrogen’s solubility, we’re now confident that bubbles could indeed form in the seas, and in fact may be more abundant than we’d expected,” said Jason Hofgartner of JPL, who serves as a co-investigator on Cassini’s radar team and was a co-author of the study.
Read the news straight from NASA here: Experiments Show Titan Lakes May Fizz with Nitrogen
Saturn’s “yin-yang” moon Iapetus (pronounced eye-AH-pe-tus) is seen in this image, a color composite made from raw images acquired by Cassini’s narrow-angle camera on March 11, 2017.
The color difference on Iapetus is due to a fine coating of dark material that falls onto its leading hemisphere, sent its way by the distant moon Phoebe traveling within the recently-discovered giant diffuse ring. This dark coating of dust causes that half of Iapetus’ surface to warm up ever-so-slightly-more than the other, making the underlying water ice evaporate and redeposit on the other side. This in turn reinforces the cycle…a positive feedback loop.
NASA’s Cassini spacecraft captured these images of a propeller in Saturn’s A ring on Feb. 21, 2017. These are the sharpest images ever taken of a propeller and reveal an unprecedented level of detail. This propeller is nicknamed “Santos-Dumont” after the Brazilian-French aviator who is hailed as the father of aviation in Brazil.
The February 2017 imaging was Cassini’s first targeted observation of a propeller. The two views show the same object from opposite sides of the rings. The top image looks toward the rings’ sunlit side, while the bottom image shows the unilluminated side, where sunlight filters through the backlit ring.
Propellers are the term given to small disturbances in Saturn’s rings caused by the gravitational influence of embedded moonlets. They are thematically nicknamed in honor of famous world aviators. The particularly large propeller Santos-Dumont is caused by an object a little over half a mile (1 km) across.
More than just being ring decorations, propellers are important to researchers because they mimic the behavior of objects in an orbiting debris field; they are sort of like miniature protoplanets inside a circumstellar disk. They were first spotted by Cassini in July 2004.
“Observing the motions of these disk-embedded objects provides a rare opportunity to gauge how the planets grew from, and interacted with, the disk of material surrounding the early sun,” said Cassini imaging team leader Carolyn Porco in 2010. “It allows us a glimpse into how the solar system ended up looking the way it does.”
Read the rest of this story here: Cassini Targets a Propeller in Saturn’s A Ring