A small module that contains some useful functions for manipulating celestial bodies.

Celestial.lua

--!strict

local atan2 = math.atan2
local sqrt = math.sqrt

local circleCircumference = math.pi*2

local function getGeoTimeForPointDirection(pointDirection: Vector3, longitudeFactor: number?): (number, number)
	local realLongitudeFactor = longitudeFactor or -1
	
	local latitude = atan2(pointDirection.Z, sqrt(pointDirection.X^2 + pointDirection.Y^2))
	local longitude = atan2(pointDirection.Y * realLongitudeFactor, pointDirection.X * realLongitudeFactor)
	
	local geoLatitude = (latitude/circleCircumference) * 360 + 23.5
	local clockTime = ((longitude/circleCircumference) * 24 - 6) % 24
	
	return geoLatitude, clockTime
end

local function getGeoTimeForInvertedBodies(): (number, number)
	return getGeoTimeForPointDirection(game:GetService("Lighting"):GetSunDirection(), 1)
end

local function applyGeoTimeToLighting(geoLatitude: number, clockTime: number)
	local Lighting = game:GetService("Lighting")
	Lighting.GeographicLatitude = geoLatitude
	Lighting.ClockTime = clockTime
end

return {
	getGeoTimeForPointDirection = getGeoTimeForPointDirection,
	getGeoTimeForInvertedBodies = getGeoTimeForInvertedBodies,
	applyGeoTimeToLighting = applyGeoTimeToLighting,
}