How Does a Telescope Work?
A telescope works by collecting much more light than your eye can and then magnifying the image. Refracting telescopes do this with lenses, and reflecting telescopes do it with mirrors. The first telescope, in 1608, made things look about three times larger.
How does a refracting telescope work?
The front lens, called the objective lens, collects light from a distant object. The bigger the lens, the more light it gathers. The lens bends the light towards the focus, the point where all the light comes together to make a sharp image. Then the eyepiece magnifies that tiny image. Where the light beams cross at the focus, the image flips upside down.
Key facts
- Hans Lippershey tried to patent the first telescope in 1608.
- The first telescope made objects look about three times larger.
- Galileo’s telescopes magnified up to thirty times.
How does a reflecting telescope work?
Early telescopes had an annoying problem: different colours of light bend differently in glass, so bright objects had blurry, coloured edges. In 1668, Isaac Newton fixed this by using mirrors instead of lenses. Light enters the tube, the curved primary mirror focuses it onto a small flat secondary mirror, and that mirror redirects the light to the eyepiece. Most modern observatory telescopes still use a version of this design.
Where can I read the full story?
This is a short version of “How Does a Telescope Work?” from OYLA Junior #12. The full article in OYLA Junior shows the path of light through both kinds of telescope in step-by-step diagrams.
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