Stars, as we all know, are essentially giant burning balls of gas floating in the vastness of space. The sun that gives our planet life and serves as the center of our solar system is probably the most well-known example of a star. (If any of your students don’t know that the sun is a star, give them the biggest F possible for the whole year. That’s day one stuff. Maybe day two.)
However, though the sun appears to be the biggest star in the sky, this is actually not true. It’s of rather average size, in fact. And, though it also appears to be the brightest, this is also not true—again, rather average. Perhaps unsurprisingly, the size of a star can affect its apparent brightness. In this case, the sun only appears to be both the largest and brightest of stars because of its close proximity to Earth. (In cosmic terms, 93 million miles is actually quite close.)
This handy dandy Demo Science science demo will help you demonstrate the correlation between a star’s size and its brightness to your students. Have at it, Hoss!
Easy Peasy Classroom Stars
For this one, you’ll need two flashlights, a pencil, two sheets of blank paper, and a roll of aluminum foil. (Fun fact: Aluminum exhibits excellent natural corrosion resistance, though that has nothing to do with its use in this experiment. Why note that, you ask? Because I like fun facts, all right?! Lay off me!)
First, cover the shiny end of one of the flashlights with a piece of aluminum foil. Using your pencil, poke a hole about the size of your pointer finger in the middle of the foil. Position the two paper sheets a few inches apart on a table or desk. (Note: You will also need a table or desk for this experiment, but it seems like a no-brainer that you’d have one of those in your classroom, so I didn’t mention it.*)
Hit the lights and hold one flashlight about six inches above each sheet of paper. Then, turn on the flashlights (obviously) and have your students observe the differences in the light patterns that appear on the paper.
Bigger = Brighter
Prepared to have your mind blown: the uncovered flashlight will produce a bigger and brighter circle of light than the foil covered one. Similarly, in the darkness of space, the size of a star affects its brightness. At an equal distance, the light of a larger star will appear brighter than that of a smaller star when observed from Earth.
* “But you mentioned it just now!”**
** Yeah, I did. Hush up, wisenheimer.