DIY Sci: What in the Flippin’ Moon Shadow?

Okay, that eclipse was totally awesome, right?  Did you notice the banana-shaped moon shadows created by tiny pinholes in paper, colanders, or even the spaces between the leaves of trees?

Did you notice that the banana was backward?  Did your observant kid(s) ask you “why?”, that one simple question, stumping your common knowledge?  

[insert crickets chirping here]

At Science Galaxy, we are all about the process of discovery, so rather than looking up the answer together, give your kid(s) the chance to figure it out for themselves.  Yay Science!


What you need:

2 different colored light bulbs (not white, large Christmas bulbs should do the trick)

2 light cords or lamps without shades

1 piece of white paper

1 piece of black paper

DIY pinhole investigation:

  1. Tape the white paper to the wall.
  2. Poke a small hole in the center of the black paper with the lead of a pencil or a skewer.
  3. Ask someone to hold the black paper about 3 feet from the wall.  Then hold the two lights next to each other about 3 feet beyond the black paper.  
  4. Turn the lights off.
  5. Have your kids play puppeteer by telling you to move around.  Try moving the position of the bulbs.  Move the bulbs closer or farther from the black paper. Move the black paper closer or farther from the wall.  
  6. Ask them to tell you what they notice.

What do you discover?

First of all, light moves in a straight line.  When we make a pinhole, only a few beams of light can pass through.  When the light is passing at an angle, the position that it hits on the wall will be the opposite of its starting position.  

Do you want to take it one step further?  Use your awesome discovery about light to create another “holy cow, wow” moment by building one of my all time favorite science discovery tools:  A camera obscura out of a cardboard box.

What you need:

1 large cardboard box (large enough to easily fit your head inside)

Duct tape

Small square of tin foil

1 sheet of white paper (or tracing paper)

One blanket

DIY Camera Obscura:

  1. Tape up the box to ensure that no light can penetrate it.
  2. Cut away part of one end of the box and fix a screen of white paper or tracing paper across it.
  3. At the opposite end, cut a small hole in the box, cover with tin foil, tape down the edges and bore a neat round hole through the foil that is no larger than the lead of a pencil.
  4. Take the box outside, or to a window, shutting out as much light as possible with a thick blanket.
  5. Put your head in the box facing the screen.

What do you discover?

Get ready to have your mind blown because an inverse image of the scene outside will be seen on the screen!  

If you missed the eclipse, or you just can’t wait until 2024, don’t fret.  You can discover the fascinating properties of light and shadow right now.  It’s all around you.  Use your skills of observation and never stop asking why.  Now go forth and turn your world (and your kid’s) upside down!

Author: Jill Katzenberger