Radioactive Decay

Well, maybe not now but it used to be the case that glow-in-the-dark watches were made with radioluminescent paint containing radium.

The instrument dials in old WWII aircraft were radioactive too so if the enemy didn't get you then your plane might! Take a look at old Spitfires and Messerschmitts at the National Museum of Flight at East Fortune, East Lothian but don't expect to be allowed to get into the cockpit!