Greetings from Magrathea

RPG.net forums, Jonny Nexus.

In my last column, I focused on terrain examples on our Big Blue. I'd like to take the same premise, but focus instead on three other bodies in our solar system. There, water is going to be little if any import, which means mountains and valleys are created through other means. There's some fascinating examples of how with a few tweaks, you can have a whole new world.

Io

Io is Jupiter's closest moon, which means that it is strongly affected by Jupiter's mass. Plus, Jupiter has other moons. Europa and Ganymede come close to Io in regular intervals (2:1 for Europa and 4:1 for Ganymede). This causes Io to orbit Jupiter in an eccentric orbit. And this physically changes the shape of Io as it orbits Jupiter, from a sphere to a elongated sphere. Here's some illustrations that go into more detail.

Io's changes in shape (also known as tidal heating) causes a lot of pressure in the moon's core. Because of this, the core is hotter than one would expect; the interior stays at 370 degrees Celsius on average, and surface temperature near the volcanoes range from 100 degrees C to 400 degrees C. Our own moon has bled out its heat; Io has not. Pressure builds, and erupts in the form of volcanoes across the surface of the moon. The largest volcano, Pele, has shot molten iron, sulfur, and magnesium 150 miles in the air, extending 400 miles from the spout. And it's not just a quick eruption either. When Voyager spotted volcanoes in 1979, their position was marked. Galileo reached Jupiter in 1995, and in 1999, Galileo took pictures of Io (it was at the extended part of the mission because the radiation around Jupiter was deemed harmful for the spacecraft's systems). Five of the nine plumes originally captured in Voyager were still active. One of the plumes moved 80 kilometers to the west. Because of all this, Io is the most active object in the solar system in terms of volcanic activity. Unfortunately for gaming implications, any atmosphere that Io would have (which it wouldn't because of its size) immediately bleeds into Jupiter because of the proximity and gravitational pull, but if we overlook that little detail, we would have a world where visibility is hampered, breathing is difficult because of the particulates, the weather and temperature varies because of the volcanic activity mixes with the general coldness of the world, and in general, life is harsh. Perfect gaming world.

Mars

Mars contains the two largest volcanoes in the solar system: Olympus Mons and Alba Mons. It also has the flattest surface in the solar system; the planet's northern hemisphere (the Vastitas Borealis) is a low-lying plain thousands of miles wide split into polygons. Some suspect that this was a large ocean, which both suggests that Mars had a climate that would support liquid water, and suggests that I'm cheating in the "look at other planets where water didn't shape geography" department.

Mars is currently dead, volcanically speaking, but this may be a recent change. As Jonny Nexus mentioned in the forum, the lack of tectonic plate movements has allowed Olympus Mons to accumulate debris and volcanic effusions longer than a typical Earth volcano. The lighter gravity also makes larger fissures in a volcano. This causes more magma to spew out, increasing the size of the volcano. Olympus Mons is twice the size of Mauna Loa (and Mauna Kea, its sister volcano, is a source of a good bar bet ó ask someone to name the tallest mountain). So, what would Mars in its heyday look like? Well, the fact that water would be carving rivers into its surface is familiar. Some of the largest gorges may have been water-related. The typical tectonic plates may not have caused mountain ranges like we are used to, but the volcanic activities do more than create isolated volcanoes. The Tharsis area on Mars can be considered to be a giant volcano, which is really a large asteroid-sized bulge in Mars, enough to possibly have altered its planetary spin. This stress on the crust causes adjoining areas to split away, causing huge rifts and canyons. Smaller canals around the larger volcanoes are created by magma rising to the crust and cooling in place, along with the general stress of the crust caused by the volcano.

Venus

Venus is like Mars in that it is not tempered by plate tectonics. However, Venus also has crippling high atmospheric pressure; this limits the size of volcanoes on Venus. It took a while to penetrate the cloud cover to determine what the surface of Venus looked like; the first four probes sent to Venus (Venera 1 through Venera 4) died on the way to the surface. Venera 7 lasted 22 minutes. Venera 8 lasted an hour, although no images could be transmitted because the cloud cover made the surface dark. Venera 9 and onward came with floodlights and cameras, and radar was added to the mix.

Venus has coronae, large oval-shaped rings 200 to 2600 kilometers in diameter. The center is bounded by a raised rim and deformities, with a moat surrounding this area. This geological structure doesn't exist on Earth to this magnitude, but if it did, it would be an ideal city/city-state/country border. Here's a three-dimensional representation of the largest corona on Venus. The fact that these exist suggests that there is some type of plate tectonics, but not in the typical Earth way we see it. It may be that Venus is just too "mushy" to support the damage and rebuild cycle needed to create true tectonics.

... and back to Earth

Let's turn back to volcanoes on Earth as I think I gave them short shrift. I'm referencing The Year Without Summer: 1816 by William Kingaman and Nicholas Kingaman. In 1815, Mount Tambora erupted. This was one of the largest eruptions in modern times, and the local devastation was both immediate and huge. However, Mount Tambora also ejected 55 million tons of sulfur dioxide gas and millions of ton of ash. The sulfur dioxide gas combined with hydroxide gas to form sulfuric acid, which stayed in the atmosphere in aerosol form.

What did this mean? 1816 was the second coldest year in the Northern hemisphere since 1400. 1817 was the fifth coldest, 1818 was the twenty-second coldest, and 1819 was the twenty-ninth coldest year. In London, the sky turned red, purple, and orange during sunsets. Agriculture in the northern hemisphere died in 1816, with late frosts killing crops. The Aberdeen Journal writes that year, "The fields, in general, are backward and in great want of warm sun, especially the grass and wheat, which in near a month later than ordinary, and are weak and unpromising at present." And no one knew why. They knew about the volcano that erupted, but no one thought that it would have caused such a long-lasting effect. Instead, they blamed sun spot activity, a general trend (1810 was a cold winter), or a series of earthquakes from the New Madrid fault. Others thought it was the end of the world, that God was punishing them. The lack of food caused riots and uprisings, which added to the general chaos.

And now lets look at this in terms of a typical D&Dx/Pathfinder campaign. You have some options:

• A volcano erupts near the player characters. Everyone dies instantly and you break out Arkham Horror. Well, that's no fun. Backing up, perhaps there are "warning shots" a day or two before the main explosion to warn the player characters. Or perhaps someone can look into the future, see the wreckage. So, they may be trying to convince an unbelieving population to leave their homes. Or maybe, just maybe, someone can go inside the volcano and relieve the pressure so it doesn't erupt. With magic!
• A volcano erupts several miles away from the characters. They players are peppered with light ash, which makes things unpleasant. Ash covers crops and makes drinking water unpotable, so until the next rain, people are going to run into problems. One sailor said, "The darkness was so profound throughout the remainder of the day that I never saw anything equal to it in the darkest night; it was impossible to see your hand when held up close to the eye." This lasted several days, with feet of ash accumulating everywhere. The area around the volcano is ravaged, but recovers somewhat quickly. Some of the area is possibly underwater, and some areas previously underwater are now above the surface. Some countries / kingdoms see opportunity to get more land. Right now, that land is useless, but it still may hold value in military terms (somewhere to dock ships, if nothing else).
• A volcano erupts across the world several months ago. The temperature drops, and people start not having food. The player-characters are brought in to help. They can hunt monsters to bring in fresh meat, or protect the existing grain towers against hordes of peasants. With magic!

Next month is looking at ecosystems, unless something else takes my fancy. And I want to end with my shameless plug of my story, Virtual Campus. Until next month.