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There have been instances of flashes in space that were attributed to sprites and fairies. Now, I know these phenomena can be explained by natural means such as blue/purple lightning. But the concept made me wonder: how could sprites or fairies, as typically represented in folklore, theoretically survive in space?

I use the words fairies loosely, but I refer to the Tinkerbell kind rather than the fae that are biologically similar to humans. My fairies are small: about 2 inches high, and they have wings. In space, their wings serve to stabilize them so they can float through the hydrogen/helium atmosphere. If brought to Earth, they can flap their wings and fly like birds. They have some primitive form of speech, but their chatter is at sufficiently high frequency that humans can't hear them (>20,000 Hz).

Like Superman, they get their energy from electromagnetic radiation from the sun (or stars). They convert the solar energy into kinetic energy for flight. Because they get their energy to perform life functions from EM radiation, they have no need for any outside sources of nutrition. They also don't need oxygen to breathe.

My fairies could be captured and bought to Earth as pets. However, they are further away from the stars, their main source of energy in space. This makes them extremely weak because they can't produce sufficient energy. They are soon unable to fly, and eventually to move at all. If they are kept on Earth for a sustained period, they could die. Not to worry - my characters have found a way to sustain them using either light therapy such as the lamps used to treat SAD, or feeding them a form of liquid starlight which they harness from the stars.

Edit: Let's assume, for argument's sake, that my fairies do exist (at least in my fantasy setting). Is the science I use to explain the existence of my creatures in outer space valid? Or are there modifications I can make to their anatomy/physiology that would make their energy-converting, space-propelling superpowers more believable?

(I apologize if this edit in any way undermines or invalidates existing answers, but I was advised to make the question less science-based.)

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Jan 3, 2023 at 5:15

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Science-wise, this doesn't stand

I'll only go over a few points, there are surely others. To be consistent throughout it, I will define the Kàrmàn's line as the beginning of outer space, so ~62 miles (100 km) above our head. Kàrmàn's line starts within the thermosphere and this would be where most fairies live.

Feeding

Let's try to have diner first : Following known biology you can't really feed from light only. Sure, there are plants's photosynthesis, but there are lots of other atoms and molecules involved : soil, air... Those are needed in most biochemical reactions because you just need solid matter at some point to sustain yourself, grow and multiply.

Unfortunately, you don't have enough of those atoms in space. To give a rough yet meaningful idea, the troposphere (starting at 3.7 miles -6 km- above ground) holds ~80% of the total mass in the atmosphere. In comparison the thermosphere holds a mere 0.02% of said total, even though it spans a much greater distance1. As far as I know, there isn't a way to convert photons to atoms, either. Therefore, properly feeding fairies will be nigh impossible up there.

Flying

Flying like butterflies or hummingbirds doesn't work meaningfully in outer space. Such flight requires a medium, some atmosphere with molecules to generate lift. As told above, the thermosphere isn't capable of providing that medium, so normally you use thrusters in place of wings there.

But let's try a broader interpretation instead. The closest thing I know about space flight with "wings" and using the sun are solar sails. Alas, their power-to-size ratio is incredibly mediocre. This means solar wings would be disproportionate to the body3, so very far from a Tinkerbell look. Even then, they would still be quite weak. To pin the last nail, those wouldn't be useable at all on Earth due to the size and weight.

The best you could have is to somehow throw your feys at high-speed orbiting around Earth like the ISS, but they won't move through their own will2. In other words, this is not really flying.

Ok, but honestly?

I'm now going to frame-challenge your question because you'll benefit much more from these lasting words than absolutely everything I wrote above.

Long ago, when I raised my doubts about Santa Claus and company, I was told this :

Well, this is a very beautiful story.

And this is indeed the most important. It's not to make hardcore scientists happy. It's whether it makes you happy with your creation. It's about making your world blossom, not letting the real-world take control of you. If this doesn't work realistically and yet you really want it, there's always the path of leaving some magic, some mystery. A story.

So here's what I'm going to tell you about joyful fairies playing in the starry nightsky : This can be a very beautiful story.


1 : Reference
2 : And eventually fall because there is still some air to drag them down. Litterally down.
3 : Easily by a factor of 100 of the body's size. From wikipedia, a ~0.5x0.5 mile (800x800m) provides 5 Newtons, which is not even a tenth of the force needed to keep you standing on Earth.

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  • $\begingroup$ This is great. Really addresses both the science and the mystery of it. Love that last paragraph! $\endgroup$ Jan 2, 2023 at 6:01
  • $\begingroup$ About the nutrition aspect: do my fairies really need to eat? Or if they can convert solar energy into ATP to perform life functions (which is the purpose of photosynthesis or any nutrition, after all) maybe glucose isn’t necessary. $\endgroup$ Jan 2, 2023 at 6:03
  • $\begingroup$ @TheresaKay If you ask your favorite gardener/florist, they'll tell you plants breathe and that would be true. Look at the Calvin and Krebs cycle, you'll see that CO2 is needed for instance. But this is even a more fundamental issue : Life is made of atoms. You (almost) don't have atoms in space. Then how can you form a thriving life there? Chemically-wise you don't have nearly enough pounds -or more accurately, moles- for the task. $\endgroup$ Jan 2, 2023 at 9:50
  • $\begingroup$ Lol ;) Assume they evolved on earth and migrated to space... The topic under discussion is whether they could survive in space without nutrition, assuming they do exist and have evolved to convert solar energy to chemical/kinetic energy. $\endgroup$ Jan 2, 2023 at 19:56
  • $\begingroup$ @TheresaKay Let's not enter the evolution process, there are only more troubles there. The path you're trying to go leads right down to a rabbit hole and it's certainly the reason you got downvoted; there are lots, lots of issues to make anything live in space, let alone flying, sun-feeding, speaking, etc. It would be too long to talk about, and anyway talking about them is missing entirely my point. $\endgroup$ Jan 2, 2023 at 20:49
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Space is not dense enough for winged flight.

In space, their wings serve to stabilize them so they can float through the hydrogen/helium atmosphere.

The interplanetary medium and interstellar medium are typically around 10^6 particles per m^3 at the high end, 70% of which is hydrogen and 28% of which is helium. Those contribute, respectively, 1.171e-21 kg and 1.861e-21 kg for a total density of ~3.032e-21 kg / m^3. The interplanetary medium is a bit denser, while the intergalactic medium is significantly less dense. These are really rough numbers, but at the exponents we're working at, it won't really change the result — 99% of the interstellar medium is significantly less dense than the numbers I'm using, so this is already a better-than-best-case-scenario setup for the density of space.

For comparison's sake, the density of air at sea level is 1.222 kg / m^3. I didn't forget the scientific notation: the density of air at sea level is ~4e20, or 400,000,000,000,000,000,000, times denser than the interstellar medium.

In order to gain velocity, the fairy will need to exert an equal and opposite force against the medium in which it is flying. Think of it as being put in space while holding a heavy object. If you weigh 100kg and the object weighs 50kg and you push the object at 10m/s, you will gain the equivalent velocity in the opposite direction, moving you at 5m/s (as 100kg x 5m/s = 50kg x 10m/s). The fairies have no such objects: they're pushing against the interplanetary/interstellar medium (or air when on earth).

If we assume that their wings cover the same area/volume per flap between space and earth, that means that in order to have equivalent mobility between space and earth, the mass of matter displaced (the volume, which is the same, times the density, which varies) multiplied by the speed of that matter must be the same between space and earth. If the fairy flaps 10x as quickly it will displace 10x as much matter at 10x the speed, for a 100x increase in total velocity.

As the matter on earth is 400 quintillion times denser than in space, the fairy will need to flap 20 billion times faster on space than on earth. Even if the fairy is so light that the air on earth is like swimming through molasses and they can fly by flapping once per second, that would require them to flap at 20GHz in space. For reference, hummingbirds flap at 10-80Hz. So let's look at speeds!

A ruby-throated hummingbird weighs 2.4 - 4.5g, is 7.5 - 9.5cm long, and has a wingspan of 10 - 12cm. You said the fairies are ~2" tall, or ~5cm tall, so I'll assume they have a wingspan of ~6.5cm. If their wing arc covers 120 degrees, the wing tip moves ~6.81cm:

diagram of how far the wing tip moves

If they're flapping at 20GHz, the wing tip is covering that 6.81cm 40 billion times per second (as it goes forward and back), or moving at 2.724x10^9 m/s. The speed of light is 2.998x10^8 m/s. It's not plausible that the same creature would be able to fly both in space and on earth via winged flight.

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    $\begingroup$ Wow. Looks like you researched this well. That is an even more in-depth answer than I expected! $\endgroup$ Jan 2, 2023 at 5:52
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    $\begingroup$ "that would require them to flap at 20GHz in space. For reference, hummingbirds flap at 10-80Hz" now do the energy requirements per second and how quickly that would kill an organism of their size and weight 😁 $\endgroup$
    – Pelinore
    Jan 2, 2023 at 8:10
  • $\begingroup$ @Pelinore Assuming no losses, and assuming incredibly light wings, the energy requirements aren't that high. $\endgroup$
    – wizzwizz4
    Jan 2, 2023 at 23:23
  • $\begingroup$ @wizzwizz4 I would have chosen "unbelievably light" since, quite honestly, I can't bring myself to believe it. I guess a graphene wing membrane would be light enough, but the structural members would add a little. $\endgroup$
    – Corey
    Jan 3, 2023 at 9:03
  • $\begingroup$ For a comparison: Solar sails are a potentially upcoming interplanetary drive technology which uses solar winds in stead of a giant propeller. Maybe that could be a starting point $\endgroup$
    – Hobbamok
    Jan 3, 2023 at 15:44
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A mix of science and fantasy. This is how most fantasy novels set things up, anyway. There are rules for how things work, and they are internally consistent within the author's universe, but doesn't necessarily reflect reality.

For the EM radiation part, you could say that the faeries require UV radiation, which is mostly (but not entirely) blocked by the atmosphere. You could keep them happy by using UV lamps on them.

This is a bit shaky, really, because UV radiation is hazardous to life as we know it, but if these fairies live in space then we must assume that they are well adapted to all forms of radiation (x-rays, gamma rays, ultraviolet radiation, nom nom).

For flight, I'd consider having their wings emit something. Emitting light might actually be enough? In space, they essentially use light emissions as thrust. Or perhaps something like an ion thruster. In an atmosphere, that doesn't work but they can use normal flight.

But I'd also consider just having them use more exotic (fantasy) elements. It's common in fantasies for fairies to be, basically, creatures that are from (or exist partially in) another dimension. The rules for how that interaction with another dimension enables their movement in our dimension could simply be your own invention, or not explained in depth at all.

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  • $\begingroup$ Thanks! This was insightful on a lot of levels. Some follow-up questions: (a) Solar panels typically use visible and infrared light. Could UV radiation be converted into chemical/kinetic energy? (b) Propelling a spacecraft by emitting light works because a huge amount of photons are emitted. Is there a way emitting light could be effective in a creature so small? (c) I'm not very familiar with an ion thruster but just did some preliminary research based on your suggestion. What anatomy/capabilities would my fairies need in order to use ion thrust to move in space? Thanks! $\endgroup$ Jan 2, 2023 at 20:03
  • $\begingroup$ @TheresaKay a) No idea actually. Research topic! I wonder if NASA makes solar panels differently to account for UV. b) You might read Andy Weir's "Hail Mary" which is really where I got that idea. Being lightweight would help the fairies use light for propulsion. c) No clue lol. Really you probably want some kind of ram scoop? Maybe the wings can unfold to a huge size to both utilize the solar wind and act as a scoop to provide material for the ion thruster... You could possibly try any of these as a separate, stand-alone question here. $\endgroup$
    – JamieB
    Jan 3, 2023 at 4:27
  • $\begingroup$ Thank you. Sounds like I have some research to do ;) $\endgroup$ Jan 3, 2023 at 17:38
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Realistically, no. There are not real creatures with these powers, and no reason to believe such a creature could exist. It is also hard to believe why such a creature would that way.

Unrealistically, yes your fairies can exist if you declare they do. You are the author and what you say goes.

You should decide how hard you want your science to be. It is not especially helpful to ask unqualified "can this exist" questions. The answer is usually no.

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    $\begingroup$ Why could such beings not exist? $\endgroup$
    – Mary
    Jan 1, 2023 at 23:21
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    $\begingroup$ @Mary Because their eyeballs will be sucked out by Space. $\endgroup$
    – Daron
    Jan 2, 2023 at 13:27
  • $\begingroup$ @Daron So blind space faeries then? 😁 $\endgroup$
    – Pelinore
    Jan 2, 2023 at 18:44

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