1 Empty, clean and dry jar
1 Blue Glow Stick
1 Tsp of diamond glitter (any will do if you can't get any)
1 Pair of gloves
1 Pair of scissors or sharp knife
1) Put 1/3 teaspoon of glitter in the bottom of the jar.
2) Put on the gloves
3) RE-READ STEP 2!!!
4) Take the scissors or sharp knife and cut off one end of the glowstick.
The plastic of the glow stick is quite thick so be careful cutting the plastic
5) Empty the contents of the glow stick into the jar. Make sure the glass tube inside does not break (yet) and don't put it in the jar.
6) Swirl the liquid and glitter round inside the jar to make sure all the glitter is wet and fluid.
7) If the glass tube has come out, put it back inside the glowstick and make sure the open end is pointing UPWARDS.
8) Gently bend and snap the glowstick. This will release the 2nd chemical inside the glass tube and CAREFULLY pour the second liquid into the jar and make sure no glass shards leave the glowstick.
9) Screw the lid on the jar tightly and shake.
10) If the effect isn't as good as you like, take the lid off and sprinkle some more glitter in, then repeat 9)
10) Enjoy your moon in a jar
:: UPDATE ::
I found that the fine glitter doesn't work as well as expected.
I'll try glitter that's quite chunky and see how that looks and post an update.