Wright Mons, supposedly a cryovolcano on Pluto. Image credit: NASA/SwRI/JPL. 

Wright Mons, supposedly a cryovolcano on Pluto. Image credit: NASA/SwRI/JPL. 

Happy New Year and welcome back, Earthlings!

When we think of lava, we think of hot, molten, spewing pieces of fiery rock from a volcano. While that may be true to Earth, the outer Solar System does not have much in the way of fire. But they do have cryovolcanoes. So what does a cryovolcano spew out?

The answer: cryolava. Literally, cold lava. Now that may seem like an oxymoron, but in the outer Solar System, cryolava could act just as destructive and geyser-like as molten lava. Earth does not have cryolava because the Earth's interior is hot and molten. But the outer Solar System bodies, like Titan or Pluto, have swirling, frozen, possible sub-surface oceans that churn the water ice and gases.

So how does cryolava act like lava? The main component is water ice and gases. But the secret ingredient is ammonia hydrates, or rather ammonia salts. Ever put salt out on your sidewalk in the winter to help the melting process of snow? It's kind of like that. The ammonia salts lower the freezing point of the water ice to keep it in a liquid state. 

How does cryolava "spew"? The constant churning of the salts, gases, and ice from small icy bodies usually come from tidal influences from either a larger planet (like Titan with Saturn) or from another moon (Pluto with Charon). These tidal pulls churn the interiors of these icy bodies and eventually spews through a vent system (cryovolcano). 

Ganesa Macula, a possible cryovolcano with flow features on the surface of Titan. Image credit: IAG Planetary Geomorphology Working Group/PSI. 

Ganesa Macula, a possible cryovolcano with flow features on the surface of Titan. Image credit: IAG Planetary Geomorphology Working Group/PSI. 

Cool, huh?

Thank you for reading and come back next week for a look at our 7th planet!