James Webb Inspired: Build Your Own Telescope

An exciting event has happened in the world of STEM – the launch of the James Webb Space Telescope (JWST)! Let’s learn a bit about what that is, how Canada is involved (that’s one of our favourite parts), and learn how to build our own telescope inspired by this out-of-this-world event!

The JWST was launched on December 24, 2021, on Christmas Eve. It was launched on Ariana flight VA256 and will be deployed in space about 1.5 million kilometres from earth. One of the coolest things the JWST does is allow us to see some of the earliest formed galaxies and stars. This will allow astronomers to see some of the oldest stars in our universe and maybe even give us some more information about the Big Bang (ask your Mom and Dad about that one) and other questions we have about the history of the universe. Pretty amazing, right?  

The JWST will also allow us to look for habitable exoplanets that we could even live on. An exoplanet is a planet that orbits around other stars outside of our solar system. We can see thousands of exoplanets today by using other telescopes such as the Hubble Space Telescope, but we can’t tell very much about their atmospheric conditions, for example. In other words, we don’t know if humans could live on these planets, and the JWST might just be able to help us know more about that. 

Lastly –  and this is our favourite part – Canada played a very significant role in the construction of the JWST by contributing a scientific instrument that helps study astronomical objects (like planets) and a guidance sensor, that allows the telescope to point at and focus on objects of interest (like planets). You could even say that without Canada’s contribution, the JWST wouldn’t be able to see, which is pretty important when you’re a telescope! Go Canada! 

Did You Know:

The JWST first started being developed in 2006! Holy flying saucers – that’s 15 years ago! Were you even alive in 2006?

Did You Know:

Even though construction was completed in 2016, it took another 5 years to test it. 5 years! I bet you are glad your next science test isn’t that long!

Build Your Own Telescope

Your challenge, if you choose to accept it:  Luke Skywalker has been stranded on the planet of Tatooine without any of his tools or his X-wing fighter. Without any communications ability, he is completely alone. Although Luke has the power of the force to aid him, he would rather not have to confront the Jawas if possible. Luke needs to build a simple telescope (refracting) to help warn him when the Jawas are approaching, and he needs your help! Let’s get to work!

Refractor Telescope

How it Works

In a telescope, the lens held next to your eye is called the eyepiece and is usually a short focal length lens or a combination of lenses. The lens at the other end of the telescope is called the objective lens. Light from a distant object is focused by the objective lens to form an image in front of the eyepiece. The eyepiece acts as a magnifier and enlarges that image. The magnification of the telescope can be found by dividing the focal length of the objective by the focal length of the eyepiece.

What You Will Need

  • 2 Converging lenses (convex lenses available at stores like Walmart or Amazon)
  • 2 Different size telescoping tubes (mailing tubes from local post office)
  • 1 Manila file folder
  • Scissors
  • Knife or saw
  • Glue
  • 1 White poster board
  • Red and black tape


  1. The body of the telescope is made from the two mailing tubes. The smaller one fits into the larger one and can slide back and forth.
  2. But what length should it be? To figure that out you need a bit of math. Ask your parents for help if you need it. The length of the telescope will be a little longer than the sum of the focal lengths of the two lenses. Add the value of the focal lengths of the short and long lens together. Divide that length by two and then add another inch. Cut both tubes to that length with a knife or saw.
  3. Use scissors to cut out two circles from the manila paper that are the same size as the diameter of the mailing tube. These circle frames will mount and center the lenses on the tube. Using your knife, cut out circles that are slightly smaller than the diameter of the lenses in the center of the paper frame circle.
  4. Glue the lenses to the center of the frame. The shorter focal length lens will be the eyepiece (as pictured below). Glue that framed lens to the end of the smaller tube. Glue the other framed lens to the end of the larger tube.
  5. OK, great job getting this far! Now, slide the two cardboard tubes together. You have now built a simple refracting telescope. Look through the eyepiece of your telescope and focus it on a distant object. Slide the two cardboard tubes in and out until you have a clear image. What can you see?

A Diagram to Help

Refractor Telescope Parts

What Have You Learned?

How is your image when you look through the telescope? Is it clear? Why? If not, why do you think that might be?

How was the observed image oriented? Note that the useful magnification of a telescope is limited by diffraction. This diffraction limit is about 10 times magnification per inch of diameter of the objective lens. For example, an objective lens 2 inches in diameter will provide a realistic telescope power of 20 times.

Happy exploring!

Article Sources (Check these out if you want more information!):
Canadian Space Agency Video
Canadian Space Agency
James Webb Telescope Wikipedia Page
NASA: James Webb vs Hubble
NASA James Webb Image Gallery


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