The City Lights Appearance control contains settings for the on-screen appearance of an object's city lights.
The checkbox on the left of the control determines whether the city lights of the object are displayed. The color setting on the right of the control sets the color of the city lights.
The City Lights Appearance control is located in the Layers section of the Appearance tab of an object's properties panel.
The displayed city lights have three settings that control their appearance, listed below the City Lights control in the Appearance Tab.
The Illuminate setting determines the condition under which the city lights are displayed. If Always is selected, then the city lights will always be visible on the night side of the object. If the other option, If Habitable, is selected, then city lights will only appear on the night side if liquid water exists on the object's surface.
The Light Map setting determines the distribution of the city lights. If Earth is selected, the Earth's city lights map is displayed on the objects surface. If Procedural is selected, a randomly generated city lights map is used instead, and the Random Seed setting becomes visible.
The Random Seed setting is an integer representing the randomly generated city lights map used when Light Map is set to Procedural. The dice icon to the right of the text box can be clicked to generate a new Random Seed.