Let's Build a Telescope!
Learners will build their very own telescope and experience what it's like to look at different objects through a telescope lens.
What You Need
Materials
Materials needed for 1 telescope:
- Two magnifying glasses
- Bristol board
- Elastics (approximately 5)
- Measuring Tape
- Sharp Scissors
- Duct tape or hot glue
Note: Magnifying glasses, bristol board, elastics, tape and glue are consumables. You will need enough for the number of telescopes your group will make (1 per learner, or working in pairs)
Guide:
Safety Notes
For younger learners, ensure proper support is provided when using scissors.
What To Do
- Hold one magnifying glass close to your eye and look through it.
- Hold the second magnifying glass at arm's length and look through it.
- Move the second magnifying glass closer and further away until you find the distance where objects are clear not blurry, but upside-down. Have a friend measure this distance.
- Roll the bristol board into a tube that is as wide as your magnifying glass. Secure it with the rubber bands.
- Mark the distance that you measured earlier onto the tube. Carefully cut a slot in the tube using the scissors. This slot should be wide enough for the magnifying glass.
- Cut the tube so that it is no more than 1 cm longer than the distance between the lenses.
- Tape the first magnifying glass to one end of the tube, then slip the magnifying glass into the slot and tape it in place.
- Use your telescope to look at distant objects!
Discovery
What is a telescope?
A telescope is a tool used to observe objects that are far away. Telescopes work by collecting and focusing the light that bounces off of objects. Telescopes can be used to focus visible light as well as x-rays and infrared radiation.
How do telescopes work?
Optical telescopes (which are used for visible light) are usually built using either lenses or mirrors (or both!). The first telescopes were refracting telescopes, which only use lenses. In a refracting telescope, the light from a distant object is bent (focusing it) when it passes through the telescope's lens. This light is then refocused a second time before it enters your eye.
Light from the real object travels in a straight line until it hits the first lens. The lens bends the light, causing it to intersect within the tube. Where the light meets, a virtual image is produced. The light is "unbent" by the final lens and enters your eye. Your brain assumes that the light from the "fake" image has travelled in a straight line, producing a virtual image that is larger than the real object!
Canada Science and Technology Museum - How to Build a Telescope - This video demonstrates how to build a telescope. In this version, the distance between the two magnifying glasses is adjustable.
What's Happening?
What is a telescope?
A telescope is a tool used to observe objects that are far away. Telescopes work by collecting and focusing the light that bounces off of objects. Telescopes can be used to focus visible light as well as x-rays and infrared radiation.
How do telescopes work?
Optical telescopes (which are used for visible light) are usually built using either lenses or mirrors (or both!). The first telescopes were refracting telescopes, which only use lenses. In a refracting telescope, the light from a distant object is bent (focusing it) when it passes through the telescope's lens. This light is then refocused a second time before it enters your eye.
Light from the real object travels in a straight line until it hits the first lens. The lens bends the light, causing it to intersect within the tube. Where the light meets, a virtual image is produced. The light is "unbent" by the final lens and enters your eye. Your brain assumes that the light from the "fake" image has travelled in a straight line, producing a virtual image that is larger than the real object!
Investigate Further
Canada Science and Technology Museum - How to Build a Telescope - This video demonstrates how to build a telescope. In this version, the distance between the two magnifying glasses is adjustable.