A World With Two Moons and No Oceans

[D. Gray Warrior]

My fantasy world is set on a planet with no oceans, instead it is dotted with lakes and rivers. The lakes are pretty large, like the Great Lakes in North America. Since there are no oceans or seas, the world is mostly land (the opposite of what Earth is) The planet also has two moons, so how would they affect the lakes?

 

[CupofJoe]

Lakes are affected by tides the same as the oceans are. That said, even with a huge lake I don't think there would be anywhere near as much of water mass so the effect would far more limited. There just wouldn't be the same momentum to build up as you get here on earth the the oceans all around the planet.
[you've got to love the internet... Water levels in the Great Lakes change primarily because of meteorological effects]
I don't know enough celestial mechanics to talk about what the effect of two moons would be as it would depend on their orbits... I've tried and gave up with a headache.
I have a sneaking feeling that I learnt long ago that the seas are salty because when they evaporate [back in to clouds] the salt gets left behind. I think that given enough time all your lakes would become salty if there was no place for them to drain into. The great lakes drain in to the Atlantic if my North American geography is right... and that's what keeps the fresh.
If I'm wrong someone will say...

 

[Steerpike]

I'll let someone else tackle the moon issue. If you're looking at a realistic portrayal of this planet, they may be the least of your problems. I think without oceans the planet is going to be quite dry and hot, and it may be difficult to maintain the water of the lakes and rivers.

The oceans on earth are instrumental in terms of the types of climates we have. They absorb the majority of solar radiation (whereas in your world most of it will hit land, tending to make the place hotter, though without water vapor in the atmosphere maybe more of the heat will escape, I don't know), and that solar radiation also causes a good deal of evaporation, which makes our atmosphere moist (whereas in your case th atmosphere will be much drier, making it hard to maintain lakes and rivers). The water vapor in the atmosphere is also an important greenhouse gas.

Oceans drive wind currents and the distribute heat around the planet. The have a big impact on global cloud formation. They're key in the earth's carbon cycle and greatly impact the amount of CO2 in the atmosphere. Weather is influenced both regionally and globally by oceans.

I don't think having a number of lakes and rivers, even large ones, dotting the land is going to have the same impact as the massive concentration of water found in oceans. So, setting the moon issue aside for the moment, I think there is a lot to consider in term of what this planet would actually be like. Maybe you've gone through all that already, but I thought I'd point out the above just in case.

 

[stephenspower]

There is a great book on exactly this subject: WHAT IF THE EARTH HAD TWO MOONS by Neil Comins, which is the sequel to his equally great book WHAT IF THE MOON DIDN'T EXIST?

 

[Steerpike]

There is a great book on exactly this subject: WHAT IF THE EARTH HAD TWO MOONS by Neil Comins, which is the sequel to his equally great book WHAT IF THE MOON DIDN'T EXIST?

I guess to conclude anything, you'd have to assign some values to the mass and distance of the moons? Two moons the size of our current moon would be significantly different from two moons the size of the moons of Mars.

 

[D. Gray Warrior]

I'll let someone else tackle the moon issue. If you're looking at a realistic portrayal of this planet, they may be the least of your problems. I think without oceans the planet is going to be quite dry and hot, and it may be difficult to maintain the water of the lakes and rivers.

The oceans on earth are instrumental in terms of the types of climates we have. They absorb the majority of solar radiation (whereas in your world most of it will hit land, tending to make the place hotter, though without water vapor in the atmosphere maybe more of the heat will escape, I don't know), and that solar radiation also causes a good deal of evaporation, which makes our atmosphere moist (whereas in your case th atmosphere will be much drier, making it hard to maintain lakes and rivers). The water vapor in the atmosphere is also an important greenhouse gas.

Oceans drive wind currents and the distribute heat around the planet. The have a big impact on global cloud formation. They're key in the earth's carbon cycle and greatly impact the amount of CO2 in the atmosphere. Weather is influenced both regionally and globally by oceans.

I don't think having a number of lakes and rivers, even large ones, dotting the land is going to have the same impact as the massive concentration of water found in oceans. So, setting the moon issue aside for the moment, I think there is a lot to consider in term of what this planet would actually be like. Maybe you've gone through all that already, but I thought I'd point out the above just in case.

The problem is that the nation in which my story takes place is temperate and forested.

But a hot, dry planet with no oceans sounds interesting though. Would the coasts of the lake be fertile regions, then?

 

[Queshire]

Just remembered that as a fantasy writer you don't have to stick with what would actually happen. If you want temperate and forested then by all means go for it. Similarly with the moons, I don't think the average reader has enough knowledge of how tides work to actually be able to know what having two moons would do to the tides. If you just come up with some tidal weirdness and chalk it up to the two moons then that should be enough.

 

[Steerpike]

The problem is that the nation in which my story takes place is temperate and forested.

But a hot, dry planet with no oceans sounds interesting though. Would the coasts of the lake be fertile regions, then?

I'm not a geologist or climatologist, so I'm basing a lot of this from my general knowledge of science and having a science background. I should add, as a caveat, that there's no reason in a fantasy world that you have to worry about this stuff being realistic, but since you were asking about moons, I figured that's the direction you wanted to go.

It seems like areas around the lakes would be fertile regions in much the same way that areas around rivers (like the Nile, or the Tigris/Euphrates) have been fertile areas on earth. When it comes to large forested areas, it seems like you might have more difficultly, because if you don't have the type of atmosphere that is going to provide a lot of rainfall, you have to consider whether there is enough water making it to these regions to sustain the forests.

Again, though, if you want to have it a certain way and aren't caught up in making it all realistic in terms of the science behind the planet, I wouldn't worry too much about it. If you do want it to be realistic, but still want no oceans and lots of wooded areas, etc. maybe there is some other aspect you could add to the planet that would explain the presence of water vapor in levels greater than expected (maybe there is some kind of canopy in the upper atmosphere) while still allowing for a lack of oceans. Maybe there is a lot of water underground that is venting vapor into the atmosphere, but in areas where oceans might be able to form, the water that rains down goes back underground. I don't know, I'm just making up some things here.

The important thing is not to hung up on this too much unless you really want the kind of story that gets hung up on it.

 

[D. Gray Warrior]

There are swamps in the forests.

 

[Terry Greer]

I love developing rationales for worlds like this.

You could get it to work if:
The planet had one large 'continental mass bulge' that was a few miles higher than the rest of the planet then the lower air pressure and altitude could make it more temperate. Especially if this 'bulge' was at or near one of the poles. any run off from these lakes would go down into the hot lowlands where it would be evaporate or sink into subterranean water courses.

What water vapour there was in the atmosphere would just precipitate out only in cooler climes i.e. over the continental bulge.

The lowlands would be hot and dry, any water would be in salt lakes - in fact a flat salt pan would probably cover most of the lowland areas (much like what happened several times to the Mediterranean when it was cut off from the ocean.

The bulge could be caused by volcanic upwelling, the remains of a collision with another planet in the distant past.

Two moons wouldn't affect any lakes much (as far as tides go) - a few inches at most. BUT if there is still water trapped deep below the salt crust you could get geysers like those on Europa at high tide as water tries to force itself out of any weakspot. This could be exceptionally strong when the two moons are in conjunction - at those times you might even get the salt flats splitting and cracking - so very dangerous.

You could have one mass at each pole - so you have two oases - separated by thousands of miles of inhospitable landscape - each with a civilization that doesn't know of the other until their technology allows one or both to make the journey.

 

[ThinkerX]

My primary world is something like the one described in the OP.

It boasts one true ocean, a round body of water larger than the Atlantic, extending from roughly latitude +50 to about latitude -20, and likewise spanning a good 70 degrees of longitude. Northern edge is just shy of the ice cap. Almost but not quite landlocked - it connects to a couple other sea's somewhat larger than the Mediterranean. I envision a major clockwise ocean current providing a bit of a balancing effect, though I don't go into detail with this in my stories.

The result is the region around this ocean is fairly normal: you got forests and swamps and good cropland around much of the perimeter, extending inland for as much as a thousand miles in places. This region is where most of the civilizations on my world are found.

Likewise, there are descent patches of land along the shores of the smaller seas.

But much of the world is arid plains country. Long rivers originating in the ice caps or large lakes wind through these plains. Those river valleys often boast forests and farmland - but grassland or outright desert is just a few days travel off.

As to the moon, my world has but one, smaller than earths.

I do have another world which has two moons, but it is almost entirely ocean, apart from some islands and a couple of continents, one of which is highly unusual.

 

[stephenspower]

I should add, as a caveat, that there's no reason in a fantasy world that you have to worry about this stuff being realistic

I heartily disagree. I put GoT down after 30 pages (before seeing Dinklage's Tyrion and picking it up again) because I didn't buy a world with seasons of variable length, nor could I buy a 700' wall, whose weight would pulverize the stones at the base. I still can't look at a map of Middle-Earth without wondering what plate was pushed up into the mountain around Mordor. I think worlds should start with their geology so you know how areas work and their cultures developed over time.

 

[Steerpike]

I heartily disagree. I put GoT down after 30 pages (before seeing Dinklage's Tyrion and picking it up again) because I didn't buy a world with seasons of variable length, nor could I buy a 700' wall, whose weight would pulverize the stones at the base. I still can't look at a map of Middle-Earth without wondering what plate was pushed up into the mountain around Mordor. I think worlds should start with their geology so you know how areas work and their cultures developed over time.

Certainly you are entitled to your view, but I am speaking in broader terms. You can find novel after novel on the shelves that don't bother much with this sort of realism and nevertheless find readers. So, empirically, a fantasy writer shouldn't feel compelled to go that route. They may lose you as a reader, but the evidence suggests that this issue will not be important to many other readers, and maybe not to the majority portion of them.

 

[ThinkerX]

I heartily disagree. I put GoT down after 30 pages (before seeing Dinklage's Tyrion and picking it up again) because I didn't buy a world with seasons of variable length,

I have suspected for a long while now the variable seasons thing is not a random or 'cool' element, but something central. An indicator that the world was 'pushed' out of 'balance' somehow. Consider the name of the series: 'A song of ICE and FIRE': Ice = winter, Fire = Summer, with both out of whack, and what magic there is directly linked to one or the other.

nor could I buy a 700' wall, whose weight would pulverize the stones at the base.

The Wall is made of ice and bound with magic. Glaciers are often that thick, or close to it. Somebody determined enough probably could make an ice wall that high, as long as the base were proportionally thick.

I still can't look at a map of Middle-Earth without wondering what plate was pushed up into the mountain around Mordor.

The mountains partly encircling Mordor are a bit odd. Mount Doom as a volcano seems feasible, which makes me wonder if some of the other mountains in the area are of volcanic origin, rather than plate tectonics. Then again, given some of the devastating events caused by supernatural sources in Middle Earths past - like the entire western portion of the continent submerging (catastrophic plate drop combined with the mother of all tsunami's?) maybe some of those mountains have a supernatural origin.

I think worlds should start with their geology so you know how areas work and their cultures developed over time.

Some try. (I did). However, what it ultimately comes down to is the story and the characters.

 

[Penpilot]

I heartily disagree. I put GoT down after 30 pages (before seeing Dinklage's Tyrion and picking it up again) because I didn't buy a world with seasons of variable length, nor could I buy a 700' wall, whose weight would pulverize the stones at the base. I still can't look at a map of Middle-Earth without wondering what plate was pushed up into the mountain around Mordor. I think worlds should start with their geology so you know how areas work and their cultures developed over time.

Here are a couple of sources that explain how the variable seasons are scientifically possible. The youtube video describes a real planet that has this property.

https://www.youtube.com/watch?v=WrHG3jgSFCA
5 Scientific Explanations for Game of Thrones' Messed-Up Seasons

Sometimes what's intuition says is impossible is very much possible and the reverse is true too. Some things that one would think are very much possible aren't, like a penny dropped from a great height being able to punch through cement. Just check out an episode of Mythbusters for things that conceptually seem to work but really don't.

I'm of the opinion of never underestimate the power of cool. Tons of things in movies, tv, and books are impractical and impossible, but are portrayed as being useful and possible because it's cool, stuff like using two guns, stuff like breaking the speed of light, etc. And they're all accepted by the audience.

On the other side of that, some things that are completely in line with reality won't jive in a story. Coincidences happen all the time in reality, but when used in a story, will stretch the audience's ability to suspend disbelief. Reality doesn't always make for a good story, nor a believable one, no matter how exciting reality was/is.

It's all about the type of story being told. If you're consistent in applying the rules of your reality and you ground that with common sense, you'll be fine. Everything else is minutia that you can manipulate how ever you want.

 

[Terry Greer]

SF demands (or at least expects) explanation and rationale for the fantastical.
Fantasy doesn't give a f**k - (but its better when the rationale is consistent).

E.g.
In GOT - the season's can be variable over generations - it doesn't matter why - they just are (though I can imagine lots of reasons why they could vary that would work scientificallyits not important to the story so its on the back burner).

In the Brian Aldiss' Helliconia series (which is SF) there's an exact same set up - variable seasons over generations. But in this case the scientific rationale (and the evolved ecology) are far more central and play an important part of the story.

In fairness they're not a full match - Helliconia is far more severe - and goes into a lot more detail of the effect the changes have on the societies that live there.

 

[Terry Greer]

Actually to see a well worked out fantasy world just check out Robert Crosby's Harn source books for his RPG game.

It's a fairly standard medieval world really - but the depth of detail is astounding - and the main Harn World book has diagrams and maps showing everything in detail - and i do mean everything - geology, climate and plantcover, linguistics, plate tectonics, ethnic groups, languages, trade winds, ocean currents, night sky - and far more - basically everything - all in an 'atlas form' that's full of images and maps.
The main book/package is called Harn World and is worth tracking down as an example of how detailed you could be if you wanted to nail down every aspect of your fantasy world.

 

[SBDanes]

The problem with not having an ocean, minus the fact that you're missing out on some amazing sightings, is that there is going to be a complete different atmosphere on your planet. Weather comes from the ocean so without the seas, the planet will dry up. Think about the Great Lakes, they are connected to the ocean. Rain would not be able to keep them filled at all times.
With two moons, you will have a semi tidal effect, but it does depend on how they orbit the planet.

 

[Queshire]

Are you sure about the Great Lakes? I'm pretty sure their connections to the ocean are either man made or flow from the great lakes to the ocean.

 

[Jesse]

True. If the great lakes were fed from the ocean they would 1. be saltier, and 2. be at a lower elevation than the ocean, which would mean that Chicago would get quite wet.