Where is the Most Fascinating Geology in the Solar System?

By Erik Klemetti | October 23, 2017 4:51 pm

I’ve spent the last few days at the Geological Society of America Annual Meeting in Seattle. What I’ve learned is that geology has definitely left the planet and there are some great questions and locations for studying geologic problems on other planets in our solar system.

This got me thinking about some of my favorite geologic sites in the solar system. Some of them are like features on Earth, others are like terrestrial deposits on steroids and others are like nothing we can find on our home planet.

So, here is a top 10 of cool geologic features across the solar system (in no particular order). By no means is this exhaustive, but it is at least a taste of the amazing geology off the Earth.

The seas of Titan: Cassini’s visit to Saturn recently met its fiery demise, but one of the most important aspects of that mission was the Huygens lander on the giant moon Titan. There, the orbiter and lander took a close look at the remarkable methane seas on Titan. I’m fascinated with what might lurk in those seas under the thick atmosphere — is there life? The ingredients of life? It might be awhile, but a robotic boat on the seas of Titan would be an amazing mission.

Composite Cassini image of Titan, with sunshine reflecting off the moon's methane seas. NASA

Composite Cassini image of Titan, with sunshine reflecting off the moon’s methane seas. NASA

The cracks on Europa: Speaking of intriguing places to potentially find life, the Jovian moon Europa may have a liquid sea underneath the thick ice that covers the smooth moon. Why is it so smooth? Some of it might be due to resurfacing from ice that erupts as water through long cracks on the moon’s surface. The Europa Clipper will take a closer look at this frosty moon. (Of course, we’ve been warned about visiting.)

Composite image of the surface of Europa taken by Galileo. NASA

Composite image of the surface of Europa taken by Galileo. NASA

The plumes of Enceladus: Now, here is a moon where the liquid ocean isn’t hiding. The plumes of ice crystals that erupt from geysers on the Saturnian moon’s Southern Hemisphere betray the liquid interior. However, as Ashley Schoenfeld mentioned in her talk here at GSA yesterday, we don’t know too much about how ice tectonics (think of it like Earth’s plates, except made of ice instead of rock), so what drives these geysers on Enceladus isn’t fully understood.

Plumes from the southern polar region of Enceladus, seen by Cassini. NASA

Plumes from the southern polar region of Enceladus, seen by Cassini. NASA

The plains of Pluto: Everyone expected Pluto to be a frozen, mostly inactive looking former planet. However, when New Horizons whizzed past it, instead we saw a startling dynamic dwarf planet. The vast, light-colored plain in the northern hemisphere of Pluto are bizarre and fascinating features that almost seem like a vast ice sheet on this distant object.

The edges of icy plains where they meet mountains on Pluto, seen by New Horizons. NASA

The edges of icy plains where they meet mountains on Pluto, seen by New Horizons. NASA

The volcanoes of Mars: Martian volcanoes are some of the biggest in the solar system. Yet, a talk by Tanya Harrison emphasized the important of small eruptions on Mars for liberating liquid water by heating the rocks near the surface. So, maybe the signs of Martian life should be found near these small volcanoes. Lujendra Ojha talked about the Medusae Fossae formation on Mars, a vast layer of rock that could be the largest explosive eruption deposit in the solar system, dwarfing the largest on Earth by over 100x (hint: it’s the Fish Canyon Tuff).

Mars Reconnaissance Orbiter HIRISE image of a collapsed lava tube from Olympus Mons. NASA

Mars Reconnaissance Orbiter HIRISE image of a collapsed lava tube from Olympus Mons. NASA

The ice mountain of Ceres: On Earth, we get volcanoes of molten rock. However, across the solar system, there seem to be a lot of volcanoes of ice (or ice-like mixtures). On Ceres, it seems that the giant mountain discovered by the Dawn mission may be an intrusive body of ice that deformed the asteroid’s surface. It is one of the most unique and bizarre features in the solar system.

The steep-sized ice mountain on the surface of the asteroid Ceres, seen by the Dawn orbiter. NASA

The steep-sized ice mountain on the surface of the asteroid Ceres, seen by the Dawn orbiter. NASA

The (lack of) craters on Venus: Our sister planet is a remarkably smooth object considering it doesn’t appear to have the same tectonics that we find on Earth. Very few impact craters can be seen on Venus’ surface so the debate rages on whether Venus may have catastrophically repaved its surface with lava hundreds of millions of years ago or whether we’ve had a gradual resurfacing. Clusters of volcanic vents (like we see on Earth) suggest it might be more of the latter. Future missions of Venus could solve this problem by mapping its surface in much higher detail (or detecting the signs of current eruptions!)

Magellan radar image of Sapas Mons, a volcano on Venus. The lighter colors are younger lava flows. NASA

Magellan radar image of Sapas Mons, a volcano on Venus. The lighter colors are younger lava flows. NASA

This does beg the question of what the right word might be for these studies. If you go by the book, geology is defined as the science that deals with the earth’s physical structure and substance, its history, and the processes that act on it. So, all this work looking the rocks and features of other planets might be not be “geology” but something new. Exogeology? Or do we just expand the definition to be any planetary body? It is an exciting time when we can consider what we might consider the field that pulls apart of the features and materials that make up other planets and moons!

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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Titan is life: Liquid methane/ethane is nobody’s life solvent. Europa, Enceladus re life: Bingo! Alas, likely nothing more interesting than a crab. Will it have all protein L-amino acids and all reducing D-sugars? Drilling through a few klicks of ice is easy – a nice lump of Pu-(238)O_2. Finessing shaft refreezing is difficult.

    Ceres! NASA don’t play that game. When failure is assured, a zero-risk business plan emerges. A chance of success is unfundable for its DCF/ROI. Venus: The solar system’s carbuncle. When will it pop? Imagine what has distilled and crystallized in the highlands.

    Tread with care. This is the only solar system with chocolate.

  • OWilson

    For me, there’s no place like home.

    Within an hour or so I can be walking on layered limestone sedimentary rock comprised of marine fossils, laid down by countless ancient oceans, or walking on glacier scraped smoothed and rounded roots of ancient mountain ranges, that display bands of brightly covered intrusions from fomenting hell deep within the earth.

    It’s called the Canadian shield (Georgian Bay) see Google images, and not only is is a geological wonder, it is also beautiful to the human beholder in a way that alien worlds can never be. (see Group of Seven artists).

    I’m sure many others feel the same way about their own favorite places on this Blue Marble!

  • https://www.facebook.com/pages/My-Original-Music-written-arranged-produced-by-ME/195887277117017 JohnnyMorales

    The northern plains of Mars sport mud volcanoes, likely the last place liquid water flowed on the planet before it all froze. Being at or near the bottom of the supposed ocean that covered the northern basin it was also under water for the longest amount of time making it the 1 of the 2 most likely places on Mars to find life.

    They and the Hellas Basin which sports an ice rich bottom land twisted and warped like taffy as well as atmospheric pressure 2x the Martian average as well as vulcanism that lasted for eons make it just as likely to be the place to have been the life’s last refuge there, and perhaps buried not far below the surface life itself.

    That’s why all efforts to explore the Surface of Mars have stayed as far away from those places as possible, and no missions have been planned.

    Calling Ceres an Asteroid is silly. It’s the only asteroid to be rounded by its own gravity and in hydrostatic equilibrium. A state that not even all planets can claim. It sports huge deposits of mineral salts that are further proof of frozen water near the surface and perhaps still liquid water further down.

    When humanity finally gets serious about expanding into our system, Ceres’ Ahuna Mons is the best place to make a base. It is significantly further from the sun than Mars significantly decreasing the danger from solar radiation, and it’s minimal gravity makes it a fantastic place to locate a space port. The gravity of Mars is 12X approx. stronger and is thus a huge barrier to making it a base for exploration.

    No other place so far has so much of what humanity needs to explore while having so little gravity, and it is conveniently located in the asteroid belt where the asteroid mining that would motivate and pay for the effort are located. We can do it all from Ceres and completely avoid the problem of having to build huge rockets to overcome deep gravity wells Etc.

  • Rick20112

    Top Ten? I counted seven. They are very interesting, but … is there something missing?

  • TKal

    Icy surfaces? Volcanoes? …Yawn. Venusian coronae are where it’s at! Huge magmatic welts surrounded by uneroded, Himalaya-scale mountain belts that show evidence of contraction coupled with core complex-style extension. What else could you ask for?

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Rocky Planet

Rocky Planet covers all the geologic events that made and will continue to shape our planet. From volcanoes to earthquakes to gold to oceans to other solar systems, I discuss what is intriguing and illuminating about the rocks beneath our feet and above our heads. Ever wonder what volcanoes are erupting? How tsunamis form and where? What rocks can tell us about ancient environments? How the Earth might change in the future? You'll find these answers and more on Rocky Planet.
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