How could my solar-powered fairies exist in outer space?

Question

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.)

Answer 1

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.

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^{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.}

Answer 2

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:

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.

Answer 3

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.

Answer 4

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.