I've been doing some world-building lately for a drama/horror/science-fiction story I've been working on and have been researching habitable worlds. One planet that has caught my attention recently is TRAPPIST-1e.
This planet is fascinating because it is both in the goldilocks zone for its star (TRAPPIST 1) and tidally locked. So, like our moon, one side is perpetually facing the sun while the other is the other side is dark. I thought these conditions would make for an exciting lighting environment within Unity to help me visualize life on TRAPPIST-1e.
The notes below are summarized from this excellent article: Alien Skies: The View from TRAPPIST-1e.
TRAPPIST 1 is much cooler than our sun, but also much closer. With the right atmosphere the result could be temperatures that could sustain life. However, due to frequent solar flares, the bright side would be too hot depending on the atmosphere, so life is more likely to occur in the twilight zone at the terminus between the light and dark sides of the planet.
TRAPPIST-1 lacks blue light in its spectrum and appears only about 0.5% as bright as our sun does on earth - this would cause the sky to have a yellow or possibly greenish-yellow appearance. The atmosphere would reflect light that appears bright reddish-orange against a very dark yellowish sky.
TRAPPIST-1 would appear on the horizon as a perpetual setting sun with a deeper red colour than it would typically have when viewed high in the sky.
CREATE YOUR MATERIAL
UPDATE THE MATERIAL SHADER
SELECT YOUR PROPERTIES
Tip: Adjust your camera in your scene so you can see the sun.
ADJUSTING THE SUN POSITION
The position of the sun in the skybox is based on the rotation of the directional light its attached to. If you are unsure which light it is attached to or no light is set you can find that information by checking Window > Rendering > Lighting Settings).
I made the following adjustments to the directional light in our scene.
As it is a very dark primitive planet. Those living near the terminus would also be able to see the stars. Next I'll be looking at create my own procedural skybox shader using Shader Graph so I'll be looking up to the heavens for more inspiration soon.