I has this idea for quite a while. I searched for information on the internet but I could see no reference. All searches gave results on the same idea but the effect was not what I'm looking for.
The constraints: a space colony on a planet away from its star, an underground colony or a hostile climate may create discomfort to colonists who desire a 24-hour day-and-night cycle.
The idea: To create a dome which mimics the blue sky and the cycles of the moon and sun. It uses the planetarium dome with some changes. The dome may or may not cover the whole colony, depending on building constraints: Underground/undersea domes will only cover the smaller gathering areas and garden areas. Some private houses may have smaller, private domes on their "balconies".
How it works: I thought of using a planetarium dome. A projector at the center will project a scenery with blue sky, clouds and the moon. A strong spotlight shoots a strong beam that will radiate light once it hits the dome. The dome is made out of unpolished aluminum. This is highly reflective but not mirror-like, allowing scattering of light from the dome, mimicking the sun. The light source on the dome is concentrated enough to make objects cast shadows. Spotlight and scenery may change colors to mimic sunrise, sunset and seasons. Seasons are important if colonists pursue their hobbies of raising plants and animals they brought from Earth, and which depend on the seasons. Domes designated for food culture and recreation may have a more comfortable weather year-round.
Question: Is this dome worth spending some time under it? Does it create the effects that I'm looking for? I'm aware that an aluminum dome above a garden area must be proofed against humidity, corrosion and mold, and cleaned regularly, but does it create a realistic day-and-night cycle?