While reading about a sidewalk astronomer in another location recently, I learned about a great little experiment that is used to illustrate and teach children about the powerful effects of the Sun, specifically the UV radiation.
We all know the harmful effects of Ultra Violet radiation from the Sun. When our skin is exposed to prolonged periods of sunlight, it will either tan or burn, neither of which is healthy for our bodies.
UV radiation from the Sun’s light destroys the chemical bonds in the tissue of our skin and over time, with prolonged exposure, the skin will wrinkle or cancers may occur. This reaction is a signal by the skin that the cells under the skin are being damaged by the UV radiation.
While light is a common term to describe all different types of light including fluorescent light, incandescent light and sunlight, it is not all the same. UV radiation is a particular form of light energy, invisible to the eye; in different wavelengths and used for variable purposes, some beneficial. For example some wavelengths are commonly used to destroy bacteria, while different wavelengths of UV light are often used in theatrical productions as “black” light.
To illustrate how this light energy can affect us, some sidewalk astronomers arrange for the making of solar bracelets. There seems to be a variety of methods used but the two I read about simply involve stringing a few of these UV beads on a piece of rawhide or even a pipe cleaner (making sure you don’t pick yourself with the ends while doing so) and then going outside into the sun. The light from the sun immediately causes the white solar beads to change a variety of colours.
Variations of the demonstration include covering some of the beads with your favourite sunscreen and watching the result as the beads change less in colour.
Another option is to put the beads in separate baggies and coat the bags with different SPF sunscreens or cover them with different sunglasses to see the degree of protection each offers.
The solar beads demonstration is a great way to illustrate to young children how the Sun can affect us. While I would like to offer this as an option for some of the young children who visit my solar scopes, it is more appropriate to a field demonstration, unless the bracelets were previously assembled and maintained in a darkened container.
For those sidewalk astronomers who want to do something simple in their area at a neighbourhood star party, it is a great idea and easy to do.