A large phosphorescent sheet with a “smiley” has been made from some black duct tape, exposed to the sun for 5 minutes and brought inside. The tape was removed leaving a “shadow” seen here. The candle is the “standard” light source.
“Continue reading” for more examples of phosphorescence and links…
The sheet is a square yard of “Kryptonite” from Scitoys. It is made of Strontium Magnesium Aluminate, doped with Europium and Dysprosium. It can be charged with an hour of sunlight and give 12h of phosphorescence.
After 1 hour it has faded considerably.
Fluorescence is the immediate emission of light less than 10 ns after the initiating exposure.
i.e. Glows while lit (most dramatically with UV)
Phosphorescence (Wikipedia) is the delayed emission of light more than 10 ns after the initiating exposure.
i.e. Glows in the dark after being lit.
Radioluminescence Glows constantly due to radioactivity.
Alternatively, it can be light-painted with a bright torch once it has become dark again.
Feeling artistic, I tried some leaves. 
Generally disappointing.
Related pages
PhosphorescenceTry something else
Can Crusher for the UniExternal links
Photo Date: Feb 28, 2015