By default, if you are on the sunny side of a planet you cannot use your flashlight.

Using this mod will allow you to use your flashlight whenever you want (except while in your ship). Works in buildings and space stations as well.

Installation:
 - If you haven't already, install the latest NMSExtender (simply extract the content of the archive to .\No Man's Sky\Binaries\)
 - Extract Flashlight.dll into your .\No Man's Sky\Binaries\NMSE\ directory
 - Use .\Binaries\NMSELauncher.exe to run the game instead of through steam or whichever you use
 - Press T to toggle your flashlight


Credits to Ant2888 for NMSExtender
https://github.com/Ant2888/NMSExtender

You can download NMSExtender here:
http://www.nexusmods.com/nomanssky/mods/9/?