Radiant Rhea

Saturn’s moon Rhea, pictured by the Cassini probe in 2012. Credit: NASA/JPL

Saturn’s moon Rhea, pictured by the Cassini probe in 2012. Credit: NASA/JPL

Hello Earthlings!

Let’s take a look at Rhea, one of Saturn’s main moons! This moon may just look like a boring bundle of craters, but several mysterious on-goings happen here! Here are SIX FUN FACTS about the icy moon, Rhea!

1-Rhea has a high reflectivity (or very bright surface), usually meaning a surface composition largely of water ice. At such cold temperatures this far out in the Solar System on Rhea (down to -364 degrees Fahrenheit!), water ice behaves like rock!

2-Images from the Voyager probes showed that Rhea's features could be divided into two regions: the first being heavily cratered, yet bright terrain with craters larger than 25 miles across and a second type of area in parts of the polar and equatorial region with craters less than 25 miles across. 

3-The average age of the plains is thought to be around 4 billion years old! Wow!

4-In 2008, the Cassini spacecraft may have found evidence of material orbiting Rhea, but is still under debate with the ring being rather tenuous, and not a permanent ring structure.

5-The Cassini spacecraft also detected a very thin atmosphere (known as an exosphere), infused with oxygen and carbon dioxide around Rhea in 2010. 

6-Rhea may have once been tectonically active! The Voyager probe imaged “wispy” lines across the surface, then reconfirmed by Cassini in 2006. These wispy lines outline cliffs that are several hundred meters tall!

A recent paper was published regarding these fascinating wispy terrains! You can read their paper here:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL079819

Thank you for reading and come back next week for a look at the South Polar Telescope!

Rhea with brightened wispy terrains! Image credit: NASA/JPL/Space Science Institute

Rhea with brightened wispy terrains! Image credit: NASA/JPL/Space Science Institute

Caitlin Ahrens