#vtt rambles

For the sake of this, I am assuming that it is a carbon-based life system as earth with similar molecular building blocks (as much as I love the idea of a different molecular building block [i believe sulfur or phosphorus has been proposed in the past as potential "life starters"] I am not smart enough to build on that).

Homeworld is larger/denser than earth with a greater gravitational pull & atmospheric pressure, with a thick/humid atmosphere, and a temperate-polar climate throughout.

(1) Planet: Larger &/or Denser than earth

This is mainly pulled from our first introduction to alien Izuku, as he leaps at Katsuki from the shuttle cockpit to the ground with ease. I had pictured Izuku as sitting prior -- or at least an awkward crouch since he was hitting the panel from the inside -- before launching himself out of the ship.

Him being accustomed to greater gravity, then landing somewhere with less pull, would give him a greater advantage in mobility

The gravitational difference wouldn't be too different however -- think about the moon landing videos and how slowly they move. With an actual atmosphere pressing downward, there may be a different effect.

(2) Atmosphere: greater pressure

Couple reasons for this one. Firstly, because of the planet being larger/denser would in turn create a greater pressure.

This would also be supported by point (1) when Izuku leaps: less gravity, less pressure holding you down, increased jumps.

Second, his shuttle was highly pressurized when they finally got the panel off -- "like a cap blowing off a soda bottle". Admittedly, idk how the crash might impact internal pressure, or the pressurizing process of our own space rockets. My assumption is that his ship would be pressurized to (or close to) Homeworlds pressure for comfortability and health of their astronauts.

I'd like to think of the difference being only slightly more extreme than human at sea-level climbing to mountain-elevation -- lest Izuku be turned into a blobfish upon exiting the shuttle lol

(3) Atmosphere: increased humidity

Like walking through fog, the kind of fog that makes it hard to breath, you know the kind.

The only 'obvious' connection is based on Katsuki's description of Izuku's skin being "delicate" (frog) -- constant humidity, less need for thickened skin.

Now here's my outlandish theory: it's because Izuku is greenish-blue.

Assuming Izuku can see (maybe a little more than) the human-visible-light spectrum (IR-ROYGBP-UV), what purpose does being green have in his environment if he can't blend in?

Well, what if the atmosphere is so humid/dense, that not all the wavelengths can penetrate it?

^This is how light penetrates the ocean on earth. Only blue & green light are visible at deeper depths, and anything yellow/red/purple would appear more grey(blue)-scaled (unless there is the introduction of a visible-wavelength light source separate from the sun).

A lot of deep sea creatures are actually pigmented with reds & purples, but in their natural depths they would appear as their colors value (light/dark -- very often dark)

So, being blue-green in color would mean blending in with your surroundings, arguably better than if you fell somewhere else of the spectrum. And, because you are a visible color, it would make it easier(?) to identify your own kind for species-prosperity or whatever.

I know I've been talking about the deep deep dark ocean, but I'm really only proposing a limited visible-light spectrum seen below for Homeworld's atmosphere. (For logic's sake and for my own selfish reason).

[Notice how the only colors not visible are oranges and reds? :) ]

[Imagine being capable seeing all the colors and more, but never actually getting to see them. Then you crash arrive on a new planet, and you're greeted by a field of pink flowers, an orange sunset, scarlet eyes, blushing cheeks. I think red would immediately become my new favorite color. ]

[there's also the red marker and the markings on the map, the "red building"/barn that loosely means salvation (because your night-blind savior is no longer tense beyond belief at the sight of it), corn fields (probably yellow but shush), fucking All Might -- but these aren't as important to my point]

(4) Atmosphere: it's a dim world

Pulling from point (3) above, not all light is able to penetrate the atmosphere, which would result in it being darker. Examples supporting this: (A) Izuku is bioluminescent (eyes & freckles), which is only really beneficial in darker environments where those lights can actually be seen.

(B) Izuku can see in the dark. Again assuming he sees normal color, and not some other form of vision. This would be an adaptation for limited light environments that would quickly become overstimulating/painful in a well lit environment (good thing Izuku crashed at dusk).

(5) Climate: Temperate & Colder

This is supported by how we know Izuku is endothermic (able to generate own heat). Katsuki mentions multiple times at how warm Izuku is, and gives the impression that he's warmer than the average human.

["only now realizes how warm Izuku’s palms are" ; "He’s warmer than Katsuki would have thought"]

While endotherms are found in every climate, ectotherms (requiring external heat for function) are restricted to warmer zones (with some species being able to function at colder zones).

On earth, endotherms in colder/polar climates have two methods of regulation: first would be natural insulation (combination of fur and fat), secondly (the one that applies to Izuku) is to have an increased core temperature (typically above 100°F/38°C). [which is real unfortunate for Izuku since he crashed in what sounds like the US Corn Belt lol].

(6) Foliage:

I think foliage on Homeworld would have to be red-ish in color for any chance at photosynthesis or like-processes to occur. Objects absorb colors that they don't possess and reflect colors that they do (example: it's why you where black in the winter (to absorb all light) and white in the summer (to reflect all light) (because light is a form of energy)), so if red light doesn't reach wherever this plant is growing, then all other light get absorbed and turned into energy (min-maxing the system) (this might also explain why many deep sea creatures on earth are red-ish -- gotta get as much light-energy as possible in harsher environments).

^this still works with point (3) because the reds would fall on the grey-scale of the environment.

End Thoughts:

What does all this mean for Alien Izuku on earth? I've kinda mentioned this previous posts, but he would probably become very overstimulated by how bright our world is. He would also likely "dry out" the longer he stayed without having a constantly high humidity. He would also start losing muscle mass if he doesn't put any additional effort in remaining fit due to the lessened gravity/pressure if he ever stayed (like how astronauts have specialized work out routines to remain strong in space).