Examine the spectra produced by other light sources, such as light-emitting diodes (LEDs), sodium-vapor streetlights, and neon tubes.
When you look at an incandescent light and a fluorescent light by eye they might appear to be the same shade of white, yet looking at them with a spectroscope reveals that they are composed of two totally different spectra.
In 1788, Comte de Buffon said that he was sure we would never know what the sun was made of. You can look through your spectroscope and prove him wrong. Be careful not to look directly at the sun, but you can use the spectroscope to look at sunlight reflected off white clouds, white walls, or white paper to see the spectrum of the sun. If you make an excellent top slit on a long tube (24 in or 60 cm) you may even see thin dark lines in the solar spectrum; these are called Fraunhofer lines and reveal what the sun is made of.
In the 1860s, William Huggins discovered what the stars were made of by viewing them through a spectroscope.
Your CD spectroscope connects you to a long history of discovery!