We all at some point in our childhoods thought that the moon is made out of cheese. As such, I thought: under what circumstances can a planetary surface form in such a manner that it is edible (and ideally, nourishing) for human beings?

Since the idea of something like this was never (according to my knowledge) discussed in science fiction, I have decided to ask the relevant question here:

  • Which (realistic) (bio)chemical and geological compositions and structures of planetary surfaces (which shall be defined as "going several meters down from the ground") make them edible for humans, e.g. non-poisonous, at least slightly nutritious and, if possible, well-tasting?

Bacterial decomposition can be ignored (unless it plays a role in the formation of such a consumable layer in your solution). It is up to you whether the underlying processes are purely chemical (and the planet, which is ideally Terran in mass and size, does not require life as such) or whether microorganisms (or other lifeforms) significantly contribute to the formation.

The surface should ideally be easily harvestable by means of shovels or other simple tools.

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    Rock salt is edible. But you are looking for complex organic compounds (proteins, carbs, fat), right? – Alexander Nov 13 at 18:30
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    this is one of those questions where no coherent answer makes sense, in terms of existing biology. anything edible gets eaten, or sequestered below something that isn't. – theRiley Nov 13 at 18:52
  • @theRiley What if there is nothing left alive on the planet? See my answer :) – kingledion Nov 13 at 19:49
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    We have that on earth, its called salt. we mine it so we can eat it. – John Nov 13 at 22:41
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    Dang, until I read the word 'realistic' I was thinking along the lines of marzipan... – Penguino Nov 13 at 23:43

10 Answers 10

The big rock candy planet

  1. A planet is entirely covered in oceans.
  2. Microbial life develops on this planet. This microbial life gains energy by transforming carbon dioxide into sugar.
  3. The ocean becomes very sugary.
  4. The planet's star suddenly increases in luminosity. The planet's oceans are boiled dry and all life is extinguished.
  5. The entire planet is now covered in a hard candy crust. There might be some other stuff mixed in, but none of it is too toxic and by mass it is mostly sugar.
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    @anon Not until 160 C. In any case, a planet covered with caramel is still edible. – kingledion Nov 13 at 18:51
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    Alternatively have it pull a mars, and have the oceans disappear through freezing out at the poles. – John Nov 13 at 22:40
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    On the big rock candy planet, you never change your socks. And the little streams of alcohol come a trickling down the rocks.... – Wildcard Nov 14 at 1:27
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    @Wildcard all the cops have wooden legs? I don't need to click on that link :) – kingledion Nov 14 at 2:17
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    @kingledion Pure booze will not kill you. I am still here. – J. Joscak Nov 14 at 10:26

On a planet without life fatty acids could build up, or imagine the ocean just before life developed, loaded with amino acids, lipids, and simple sugars. Then the planet gets yanked out of orbit or the star burns out, either way the planet freezes, and now you you have a planet covered in frozen broth. It will be a thin broth but some places may have have higher concentrations due to freeze separation (similar to making applejack). It will be a bit salty though.

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You don't have to look very far, all you need is limestone or chalk.

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Limestone (or the crumbly version of it: chalk) is made primarily of calcium carbonate, CaCO3. You probably know it better as antacid:

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This might be extremely useful if you have a candy-covered planet as suggested in one of the other answers!

Calcium carbonate is nontoxic and easily digestable by our stomach acids. It is a rich source of calcium (obvisouly) but also other important mineral nutrients such as magnesium, occasionally iron, manganese, and phosphporus.

Bottled mineral water that flowed through limestones is usually very tasty, because it absorbed all the minerals (and carbonate) from the water.

The problem is that is has no energetic value since it has no organic material in it, but it's a great supplement for those minerals and to improve the taste of several things.

  • So I was going to upvote this because its really the only realistic answer unless you count my hack ice planet one. Then I realized its not realistically possible to coat the whole planets surface in calcium carbonate. The biology and geology needed to refine it defies reason. – anon Nov 14 at 1:57
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    @anon I don't think it's reasonable to expect any planet or moon to have a 100% homogenous surface composition. I'm all for half limestone half jelly beans planet. – Gimelist Nov 14 at 3:26
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    By that right Earth in many ways satisfies the scenario. You can eat ice, drink water, eat salt, eat limestone. There are plenty of minerals that you can consume from the ground. You can even get edible organics from soil. – anon Nov 14 at 15:56
  • @Gimelist The Empire will be surprised to hear this. – Azor Ahai Nov 15 at 5:53

1) On an ocean world

2) A simple algae evolves that stores its sugar externally in the form of long filaments. These algae like many other thrive on the surface and clump together forming films.

3) The filaments dissolve into the water.

4) As time progresses the algae grow across the planet at the same time the dissolved sugar content makes the water gelatinous and allows the algae to cover the whole surface of the planet.

5) Now that the Algae cover the surface and beneath becomes too crowded the filaments grow into the air like hair.

6) Because the oceans have been covered by the algae, less water is evaporated from the oceans resulting in less rainfall and resulting in less surface moisture and more sunlight.

7) Because of decrease surface moisture and storm systems the filaments begin to grow long and brittle. The winds whips up the filaments into balls forming a:

Complex global terrain of Cotton Candy

Of course the algae dies off in places where the cotton candy accrues so much that it blocks out the sun. But then where it isn't accruing it is still growing which leads to the formation of complex terrain. At some point its possible for all the algae to be wiped out.

Ps the cotton candy solves snowball Earth by acting as an insulator and trapping heat inside.

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    You're missing the best part of this scenario...cotton candy tumbleweeds! – chif-ii Nov 14 at 15:48

Water is nutritious so how about an ice planet

for kicks you can throw in a photosynthesizing bacteria that lives on the ice that adds nutrients and flavors. It would be a snowcone planet

Food is a blend of complex organic molecules.

Complex organic molecules for the most part don't form naturally. There are simpler organic molecules that do form naturally but they wouldn't make for good eating.

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    Water is... nutritious?? I’m not sure that word means what you think it means... – Joe Bloggs Nov 13 at 21:53
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    @JoeBloggs Water is a vital nutrient, in fact you die if you don't ingest enough. – John Nov 13 at 22:49
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    @JoeBloggs I had to google it just to be sure....goddam technically correct – Shadowzee Nov 13 at 23:14
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    But nutritious doesn’t mean ‘is a nutrient’. Calcium is a vital nutrient: you would never say a block of chalk was nutritious. – Joe Bloggs Nov 14 at 6:52
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    @JoeBloggs It's 'nutritious' in the same way the Trix is "part of a balanced breakfast", so long as that breakfast includes everything needed to be considered 'balanced' even if the bowl of Trix wasn't included. – Theo Brinkman Nov 14 at 19:42

Many soils are already edible.


In fact, clay is harvested and purified as a nutritional supplement. It doesn't add nutrition but it is used in that manner...you can eat clay to help detox the body from bad foods or from toxic materials.

Check out: https://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/french-green-clay

It would be unreasonable for the core fo the planet to be edible. Just the way planets are formed, it's not gonna happen.

But an edible crust a few km thick? Sure, not a problem.

Initially, cover the whole planet with a single thin mat of teeming bacteria. Differentiate that mat into layers - the photosynthesizers in the top layer, and those that eat the leavings of the top layer, while providing structure and support below, and converting the surface into minerals which get passed up.

The support layers build deeper and deeper, each layer having to bear nutrients, hydration, etc to the layer below.

You essentially have a giant single-planet blob of mushroom. Cut into it and the support structures must be built thicker and stronger the deeper you go.

Whether it tastes of mushroom or sugar candy or processed beef or chalk doesn't matter - the whole thing is either alive, or support structure, and the vast mass of it is needed to transport nutrients from below and energy from above. There's competitive pressure to build the layer higher to compete locally for nutrients (the same pressure that exists making our forests taller), and to dig for minerals deeper and faster. So the layer of biological stuff gets deeper.

It's like a tree, if trees were umbrellas and treetrunks never developed the solidity of wood so the umbrellas had to float on top of supportive goo.

Titan has a hydrospheric cycle based on methane, which leads to simple carbohydrates forming naturally and depositing. With proper sedimentation you can end up with rocks composed of alcohol, sugar, caffeine or psilocin - without any biological activity.

  • Caffeine and psilocin will still take some handwaving, though. – Renan Nov 15 at 10:23

At first there was an Earth-like planet. An evolutionary arms-race with giraffes has pushed apple trees to grow ever larger. The fruits also grew, until they reached astronomical proportions.

The original planet has since then shrunk considerably, and now shares its orbit with a dozen Moon-size apples. You can land a spaceship on them and have a taste!

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    Not my downvote, but... with questions that have the "science-based" tag, answers like this, while imaginative, get downvotes because they throw out every part of science. Fruit typically wouldn't grow larger than could be eaten; fruit couldn't grow bigger than the available water; trees couldn't grow that tall, animals certainly couldn't grow that tall, getting a giant fruit into orbit involves massive tangential velocities for it to miss the planet on the way down, apple wouldn't remain edible and cells wouldn't remain intact past the surface layer, etc ad infinitum. – Dewi Morgan Nov 15 at 15:07
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    Thanks, good points! On the other hand, plants that don't bear space-faring fruit are inevitably doomed to live and die in a single star system. Plants with space-faring fruit are thus at an evolutionary advantage over cosmic time scales and will eventually dominate. They would likely have some differences from the common apple of course. – Daniel Darabos Nov 15 at 16:04
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    I agree: Panspermic seeds would need a LOT of differences, yes: you want something light, resistant to radiation, cold, heat and acceleration. Edibility wouldn't be a necessary trait, so fruit would be a waste of mass. Escaping from the planet would mean reaching escape velocity (mach 33, 11km/s, 25,000mph), no matter how tall the tree was, unless it was some kind of orbital elevator, which isn't feasible. – Dewi Morgan Nov 15 at 16:21
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    Being edible would help with dispersal in a galaxy with space-faring planet-sized herbivores. (I totally deserve the downvote. I apologize for this answer.) – Daniel Darabos Nov 15 at 16:54
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    Mooncows! Of course! Tipsy mooncows lurching through the solar system, drunk on fermented moonapples. It might not be super-hard science, but it'd be hard cider, and a damn good story! And if we relax the size of the planets a little (OK, OK, maybe a LOT!), it becomes close to reasonable. Say, a planetary disk that never coalesced beyond the planetoid stage? Lots of little planets and asteroids and other solar system objects with space-plants on, growing from the ice and minerals. Avoids the gravity-well problem and prettymuch FORCES them to try to move to other bodies. – Dewi Morgan Nov 15 at 17:03

Earth is like that in some places.

In the north and south polar regions, you can eat snow. Granted, it'd better be fresh snow from areas far from cities. It is nourishing because your body needs water, though it's a bit tasteless when compared to about anything else.

In the Andes, you have dome areas where the top-most layer of the soil is pure salt. That's because millions of years ago the Andes were underwater - the mountains went up when their tectonic plate passed over another, and they are still "growing" a little every year. A lot of oceanic salt got trapped. Some of it was taken from the underground by lakes, and when the lakes dry, they form regions called salares. The largest one is in Bolivia:

Salar de Uyuni

Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat, at 10,582 square kilometers (4,086 sq mi). It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes and is at an elevation of 3,656 meters (11,995 ft) above sea level.

The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average elevation variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine (...)

Salar de Uyuni is estimated to contain 10 billion tonnes (9.8 billion long tons; 11 billion short tons) of salt, of which less than 25,000 t is extracted annually.

Look at some people literally harvesting the floor for salt!

The floor is kitchen salt!

Now imagine actual Earth is the oceans dried, for whatevdr reasons. More than 75% of the planet's surface would be covered by meters of salt.

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