In this month’s Let’s Discover!, we are going to make water glow — or fluoresce, rather. You’ll need a few simple items and one special item: water, a washable highlighter or two, a container that can get dirty, some needle-nosed pliers and a black light.

The black light is the least common, but they can be found in various forms for $15 or much less, whether as a handheld device or a bulb to go into a home fixture. You can extend this activity with other things that fluoresce, but we’ll cover that below.

There is one part that you’ll need to do for your child, and that is removing the end cap of the highlighter. Find a safe, mess-friendly place for all of this. What we want to do is break off the back end (the non-felt-tipped end) and remove the felt ink reservoir. To make some water that glows beautifully, we dip our felt ink reservoir into the water. You will immediately see the bright highlighter ink swirl out as it disperses into solution, and you can speed up the process by squeezing it. It may glow a little in sunlight or under fluorescent light, but it will glow the best when the rays from a black light hit it (which works in the light, but best in the dark).

Highlighters appear to be brighter in colour than regular markers because they fluoresce: they actually emit visible light (in a variety of colours, nowadays) when they are struck by UV light, which is what a black light emits (take care not to look directly into black lights if you can help it). Highlighters aren’t the only fluorescent materials however: your teeth will likely glow under the black light, as will many laundry detergents (which dye your clothes to fluoresce in sunlight) and new paper money. It can be lots of fun finding things that glow — certain flowers even have a fluorescent “nectar guide” that leads bees and butterflies to their pollen.

For a video of this experiment check out http://www.youtube.com/watch?v=R65G2Rd91MI

And, don’t forget to check-out the Discovery Centre’s brand-new exhibit, TANKED: An Atlantic Aquarium Exhibit. It has loads of Nova Scotia fish, a giant lobster and touch tanks full of fascinating sea creatures. Wednesday evenings, we’re open until 8:00, and our touch tanks are often open all evening!