Space Stuff

How Does a Telescope Work?

There are two types of telescopes that are widely available to the public, those being reflecting and refracting telescopes. These function in two different ways, but both achieve the same effect, but how? Both types utilize a wide hole on one side, the side facing the distant object, to funnel photons (light) into the telescope to enlarge the image so that the distant object can be viewed. Although the overall idea for these telescopes is the same, the way they enlarge the image to be viewed is very different.

Refracting Telescope

Refracting telescopes are what most people think of when they think of telescopes. These types of telescopes work in a relatively simple way:

1. A distant object creates light particles (photons) which travel through space in all directions until they are intercepted or hit something
2. Photons hit the large lens at the front of the telescope (the side facing towards the object of interest), which concentrates and focues the photons the photons into the eyepiece
3. The eyepiece expands the image, allowing the viewer to see the image in detail

These telescopes are a fairly simple choice for beginners, and can easily expand images of the moon, Mars, Venus, and other close space objects. However, these telescopes have certain limitations which makes them a less optimal choice for further objects. They suffer from an inability to scale up for both cost and physical reasons, meaning that the amount of objects they can enlarge to a viewable size are limited, especially for amateur astronomers.

Reflecting Telescope

Reflecting telescopes follow a similar procedure as refracting telescopes, however the internal concentration and focusing of photons is handled differently.

1. A distant object creates light particles (photons) which travel through space in all directions until they are intercepted or hit something
2. Photons hit the large lens at the front of the telescope (the side facing towards the object of interest) and hit a large mirror at the back of the telescope
3. The large mirror then reflects and concentrates the light into a second mirror back near the front of the telescope
4. The eyepiece expands the image, allowing the viewer to see the image in detail

Reflecting telescopes are much more complicated than their refracting counterparts, however they make up for this complexity by being much easier to scale up, as instead of having one large mirror they have several smaller mirrors. They can be more expensive than refractors at a small, but they allow you to see much more of the universe in more detail.

Why Put Telescopes in Space?

While ground-based telescopes are substantially cheaper than space-bound telescopes, they encounter one major downside—the atmosphere. The atmosphere, depending on how much the light travels through (for example, a telescope facing straight up will have to deal with much less atmosphere than one pointing parallel to the ground), will distort images. While this may not be a large issue for amateur astronomers who just wish to view celestial objects and not to study them, for organizations such as NASA, who want to study deep space objects, this distortion can lead to complications. Overall, viewing celestial objects while in space poses less complications with the data, and this is especially important for objects outside of our solar system.

Hubble

The Hubble Space Telescope is perhaps the most famous telescope of all time. Launched in 1990 and named after an influential astronomer, the Hubble Telescope has led to advancements in our knowledge of galaxies and black holes. It has created many famous images, such as the Pillars of Creation, Ultra Deep Field, and the Crab Nebula. Each of these images have improved our understanding of the universe and helped to show the general public why NASA's studies are important.

James Webb

The James Webb Telescope, while not as old or as well known as the Hubble, is still a critical telescope for NASA. Being launched into space in 2021, it has already helped make important discoveries regarding exoplanets and other spatial objects. While it hasn't completely replaced Hubble yet, it has significantly improved our ability to view old and distant objects that Hubble simply could not view. It is currently our most advanced and capable telescope we have launched into space, and holds tremendous potential for the future.