At Home With Hands On!

Safely Watch the Solar Eclipse (8/2/17)

Make an Eclipse Projector

MATERIALS:

  • A medium-large cardboard box, or a cardboard tube
  • Scissors
  • Aluminum Foil
  • Duct Tape
  • Thumbtack
  • Cardboard Cutter or a Sharp Knife
  • Sheet of White Paper
  • Glue or Clear Tape
  • Adult Assistant

 

CARDBOARD BOX PROJECTOR INSTRUCTIONS:

  1. Using Duct Tape, seal the bottom flaps of a cardboard box.
  2. Cut a piece of white paper to cover the inside wall of the box’s shorter sides. Tape or glue the sheet of white paper onto the inside of the cardboard box.
  3. Ask your Adult Assistant to carefully cut a 2-inch square opening in the other short side of your cardboard box (the end opposite to the white paper) using a knife or a cardboard cutter. (Note: For a larger projection of the eclipse, use a larger (especially longer) cardboard box. You could even tape together two boxes for this project.)
  4. Then cut a rectangular viewing hole in one of the longer sides of the box (About 2-inches by 6-inches). It should closer to the end with the white paper.
  5. Use the scissors to cut a square piece of Aluminum Foil that is slightly larger than the square hole in the box (we recommend a 4-inch square). Smooth out any wrinkles or crinkles in your aluminum foil.
  6. Tape the aluminum foil over the square opening in the end of the cardboard box.
  7. Use a thumbtack to poke a small hole in the very center of the aluminum foil.
  8. Using Duct Tape, seal the top flaps of the cardboard box to keep any light from shining in through the sides.
  9. During the eclipse, aim the pinhole end of the box toward the sun. Adjust the angle of the box until you can see a small projection of the eclipsed Sun on the white paper inside of the box!
solar eclipse - box

CARDBOARD TUBE PROJECTOR INSTRUCTIONS:

  1. Make sure that the end caps have been removed from both ends of your cardboard tube.
  2. Cover one end with a sheet of aluminum foil, and secure it in place with Duct Tape.
  3. Gently smooth out any wrinkles or crinkles in the aluminum foil (but it doesn’t have to be perfect).
  4. Use the thumbtack to poke a small hole in the center of the aluminum foil.
  5. Tape a piece of white paper over the far end of the cardboard tube as a projector screen.
  6. Close to the end with the white paper, cut a small viewing hole using a sharp knife.
  7. With your back facing the Sun, aim the pinhole end of the tube toward the sun. Angle the tube until its shadow is a nearly-round circle (this shows that it is angled along the rays of the Sun). Look through the viewing window to see a projected image of the eclipsed sun on the paper screen!

HOW DOES IT WORK:

The Eclipse Projector is an example of a very old technology, known as a Camera Obscura (or a Pinhole Camera). The bright light from one room passes through a small opening, or aperture, that separates it from a much darker room.

When the light strikes a screen inside of the darkened room, an image will appear. But strangely, the projected image appears upside down! If you find this is a bit confusing (like I did), then check out the diagram below. Light will travel in straight lines. Notice how the blue line (which represents light reflecting from the candle holder) actually intersects the red line (representing the candlelight) and hits the screen at the top!

Amazingly, our eyes work the same way as the camera obscura: by letting in light through a small pinhole opening (the pupil) and then collecting the inverted image at the back of the eye (with our light-sensitive rod and cone cells). Luckily for us, our brain automatically corrects the image by flipping it right-side up!

THE MORE YOU KNOW:

Eclipses happen when the Sun, Moon, and Earth are in alignment, causing shadow effects that seem almost magical. Syzygy is the term given to this special straight-line configuration of multiple objects in Space. When objects in space are aligned, they are “in syzygy.”

Lunar Eclipses happen when the Earth moves between the Moon and the Sun, causing the Moon to pass through the shadow cast by the Earth.

Solar Eclipses happen when the Moon moves between the Earth and the Sun, causing the Moon to visually block out some (or all) of the Sun.

There are actually different types of Solar Eclipses:

 solar eclipse - types

During a Partial Eclipse, the Sun and Moon are not perfectly aligned, and the Moon only partially blocks out the Sun. Partial Eclipses can be seen by a larger part of the Earth outside of the line of totality, and so they are more popularly observed.

During an Annular Eclipse, the Sun and Moon are precisely aligned; however, the apparent size of the moon is a bit smaller than the apparent size of the Sun. The Moon actually orbits the Earth in an elliptical path, meaning that it is sometimes further away from Earth (causing it to appear slightly smaller in the sky) and it is sometimes closer to Earth (causing it to appear slightly larger.) During an Annular Eclipse, the Moon blocks much of the Sun’s surface, but a bit of the Sun is still visible in a ring around the silhouette of the Moon.

During a Total Eclipse, the Moon appears to completely block out the disc of the Sun. When this happens, a glowing ring of illuminated Solar atmosphere (called the Sun’s corona) can be observed around the silhouette of the moon. Total Eclipses are very rare because totality only occurs along a thin line on the surface of the Earth.

solar eclipse - alignment

For even more information about Solar Eclipses and how to safely view them, check out this awesome article from NASA’s website!

https://eclipse2017.nasa.gov/eclipse-who-what-where-when-and-how

GOING ONE STEP FURTHER:

  1. Solar Eclipse projections can be made in a number of unexpected ways. Any small opening (or aperture) that allows the light of the eclipse through will cast sun-projections on the ground! Try this: stand with your back to the sun, hold your hand above your head and make a tiny opening with your thumb and pointer finger. Now look at your shadow…how does the light coming through your hand appear on the ground?
  2. Or try this: With two paper plates, punch a hole in the center of one plate using the point of a pencil or pen. Now hold the un-holey plate so that it directly faces the Sun and wave the plate with a hole above it. Try experimenting with extra holes punched in one plate, or cutting small shapes into the plate. How does this affect the projected light?

And don’t forget to stare (safely) at the Sun on August 21st, 2017!