Check out a useful free toolkit.

Ricardo Viana shared a free custom procedural environment shading toolkit for Blender. The system features a number of customizable parameters letting you set up different scenarios. 

Features

• Sun direction 
• Night with/without stars
• Sun and horizon colors
• Sun intensity and scale
• Floor height

Please note that it works with both Cycles and Eevee. Please note that in Cycles you need bigger sun sizes. A moon is not included.

You can learn more and get the pack here.