albedo

The albedo is a unit understood to be between 0 and 1 which measures the sunlight reflected back into space by a planet. The brighter the planet, like a block of ice for example, the more light it reflects and the less heat it keeps. It will have an albedo of around 1. By way of example, the houses with white facades in Greece insulate against heat by reflecting light. Conversely, the darker the planet, the more it will absorb light and heat, its albedo will be around 0.