solar-balloonWe didn't include this particular experiment in our shopping list, as the tube's kind of expensive and can only be used for one particular experiment, BUT it's an incredible blast to do in the summer.

Here's the main idea - an incredibly loooooong and super-lightweight black plastic garbage bag is filled with air and allowed to heat itself in the sun. In a few short minutes, the entire 60-foot tube tube rises into the air. Before you try this experiment, try the Hot Air Balloon first!

Order the Solar Tube here.

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Your kids will actually get to see several science principles in action, including: hot air is less dense than cool air (when the balloon rises); black objects heat up faster (when the air heats up inside); gases expand when heated (you'll see the bag self-inflate as it heats up).

Here's what you do:

1. In the morning during summer, when there's no wind and it's still cool, stretch your tube out flat in the shade. If it's already hot, fill the tube indoors with a fan. It's the temperature difference that will make this bag rise. If the temperature of the air inside the tube is nearly the same as the outside air, then it will simply remain on the ground.

2. Open one end of the tube and (with a few friends to help you), walk (or run) to fill it full of air, and tie off the end when it's full. It may still be a bit baggy in some places - don't worry - it will fill itself out when it heats up.

3. Tie off a length of lightweight string (like kite string) to one end. This will make sure you can get your tube back!

4. Bring it into the sun and watch it slowly rise of the ground.

NOTE: Kids can get a bit overexcited when they do this experiment, so watch they don't puncture the bag. You can seal it back up with a thick strip of lightweight packing tape if needed.

DO NOT let the solar tube rise without the string. If it gets loose at higher altitudes, it's a serious threat to airplanes.

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Comments

6 Responses to “Gigantic Solar Balloon”

  1. Thanks! I corrected the typo.

  2. under the note it says “think strip” of tape.

  3. Oops – you’re right! Sorry – I fixed it today. 🙂

  4. Stacey Thomas says:

    Aurora had a mis-type during this experiment. I think she was too excited with this experiment to proof-read. Aurora meant “thin strip” of lightweight packaging tape.

  5. Rani John says:

    Thin strip of lightweight packaging?