Vacation Exploration: Star Projectors

shining-stars-kidAh, winter. It’s cold and dark out, yes. But one of the best parts of winter is the star gazing. The stars come out early enough for even your youngest children to observe…just make sure you bundle up when you go out to see them!

After you’ve stargazed a few times, and picked out a few constellations with your kids, you can bring the learning inside by creating your own constellation projectors. This activity is based on “Shining Stars” from Boston Children’s Museum’s Beyond the Chalkboard curriculum. Click here for those more detailed instructions. Constellations are pictures that people have imagined in the patterns of the stars, and they are familiar in some form or another to most children. Creating homemade projections of these constellations is a fun way to connect to astronomy at home. This activity is a good follow-up to Constellation Creation, posted on this blog earlier this week, and also from Beyond the Chalkboard.

Materials

  • Flashlights (see Preparation below for notes on these)
  • Paper cups (a few per child) (see Preparation)
  • A thumb tack, paper clip, sharp pencil, or wood skewer
  • Pen or thin marker

Preparation

Flashlights – The kind of flashlight you use for this activity is important. LED flashlights are preferred, but whatever kind you use, it is best if you can remove the reflector from the head of the flashlight. The reflector is the shiny, silver cone that lies just inside the lens, and the bulb of the flashlight typically shines inside it. Here’s what it looks like:

flashlight-reflector

Some LED flashlights make it impossible for you to remove the reflector, so check your flashlight before you start. Old school flashlights with removable bulbs almost always work, and are less expensive than LED lights, but are not as bright as LEDs.

Cups – the paper cups should fit over the lit end of your flashlight, and the flashlight should fit at least part of the way into the cup. It might be a good idea to have a few different sizes of cup available for testing.

Remove the reflectors from your flashlights, and make sure all of the flashlights are working.

Instructions

  1. Talk about constellations you know, or look some up online, or in a book. You could also try the Constellation Creation activity, posted earlier this week, before you make your fancy projectors.
  2. Look at the constellations you found, and choose one you like.
  3. Notice how a cup will fit over the flashlight, and turn the flashlight on with a cup on it. What do you notice? You should see the cup is all lit up. Poke a few holes in the bottom of a cup, then slide it on the lit-up end of the flashlight again. Turn off the lights, and point the flashlight (with the cup on it) at a wall. What do you notice? You should see a projection of the holes you made as points of light on the wall. If the holes look fuzzy, you may not have taken the reflector out (see above).
  4. Make some new cups with holes representing stars in a constellation.

You may notice that if you poked the holes going in from the bottom of the cups, so that the constellations look correct on the bottom of the cup, then they will look backwards when projected. Try either poking the holes in the correct configuration from inside the cup, or draw the constellation dots with a heavy, dark marker (like a Sharpie) on a piece of paper, flip the paper over, hold that paper over the bottom of the cup, and poke the holes of this backwards constellation through the cup. Your constellations should now project correctly.

Some children who have made these projectors have used black construction paper circles on the bottoms of the cups, before poking the holes. Some kids have trimmed long cups so that they were shorter and easier to handle. Some children have even decorated the outsides of their cups with themes that match their chosen constellations. What could you do?

Notes

  • Mag Lites are the best flashlights for this activity, as they are LED, bright, and have removable reflectors. The Mag Lite Mini LED 2-Cell AAA Flashlight is around $15, and the AA model is around $20. You can find Mag Lites at Amazon (click here for an example), Home Depot, Lowe’s, etc. You can try this activity with less expensive, incandescent bulb flashlights – just be certain the reflector is removable, and that your room is nice and dark to accommodate the dimmer lights.
  • Doing a simple image search for familiar constellations like Orion, Cassiopeia, Ursa Major, and others will yield many results.

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