Telescopes have the ability to see objects from hundreds of thousands of miles away in space, but how do they work? Truth is, telescopes come in many shapes and sizes, and they range from the little plastic tube that you can buy at the toy store for $2 to the Hubble Space Telescope. On the middle end of the spectrum, you have amateur telescopes that fit in the middle, and while they are not as powerful as the Hubble, they can still accomplish incredible things like read the writing on a dime from more than 150 feet away. When it comes to the amateur telescopes of today, you have two types: a refractor telescope and a reflector telescope.
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The Two Telescopes
Instead of using lenses, the reflector telescope uses mirrors while the refractor telescope uses glass lenses. They both accomplish the same thing, but they do it in different ways. To understand what makes telescopes work, first, let’s look at why you cannot see far away. For example, why can’t you read a dime from 150 feet away without a telescope? The answer is that the object does not take up enough space on your eye screen. To give an analogy, it is like how digital cameras couldn’t see the writing on a dime because it does not cover enough pixels on your retinal sensor.
Using a bigger eye, you can collect light from the object and create a bright image that will magnify the image to stretch it over more pixels on the retina. This is what lets you see further away.
The Objective Lens and the Eyepiece Lens
The objective lenses, also known as the primary mirror, will collect light from distant objects and bring the light to a point of focus. On the other hand, you have the eyepiece lens, and this takes bright light from the objective lens, and it focuses the objective lens. In other words, it spreads out and magnifies the primary mirror. Telescopes operate using the same principle that you find with a magnifying glass. In essence, the idea behind it is to collect as much light as possible to form images inside the telescope, and the light magnifies it like a glass that takes up the space on your retina.
The Ability to Collect Light
Your telescope’s light collecting capabilities relate directly to the diameter of the lens or mirror that is known as the aperture or objective lens. The aperture gathers light, and the larger your aperture, the more light that your telescope can collect and bring into focus. The more light that you have, the brighter the final image will be. How does a telescope magnify things? A telescope’s ability to magnify images will depend on the lenses and the combinations that are used. The eyepiece will perform a magnification, and that magnification can achieved with almost all telescopes.
Why Can’t the Eye See Objects at a Distance?
While human eyes do have the ability to see for long distances, most of it will appear to be a tiny point in the sky. For example, humans can see the Andromeda Galaxy, which is more than 2.5 million light years away, but even in a massive galaxy like Andromeda, it appears as a tiny point in the sky to the naked eye. As an object gets further away, the harder will be to see, but that is why telescopes have proven an invaluable tool for exploring the known universe.
Will a Bigger Lens Yield a Bigger Image?
If you want to make a distant object appear bigger and brighter, you want to collect more light. You can create a brighter image so that it takes up more space on your retina. In fact, the big lens of telescopes will collect more light than what the naked eye has the ability to collect, and this focuses the light to a point from inside the telescope. Your telescope’s ability to collect light will largely depend on the objective lens, which will gather and focus the light from a narrow portion of the sky. The performance of your telescope will depend almost entirely on the size of your objective lens, which is why you should look for a telescope with a larger objective lens.
Refracting telescopes have sometimes been seen as inferior. If you have ever watched light bend through a prism, then you know where the problem comes in at with a refracting telescope: the lens. As light passes through the glass, it will slow down, and while lenses have the shape to bend light, the amount of bending will depend on the wavelength. Understanding this, however, you can make an informed decision on the best choice for a telescope. Reflecting telescopes can be much larger, and they look deeper into space because of the design.