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How Do Stars Look Through a Telescope?

girl looking at stars with telescope
» Telescopes » How Do Stars Look Through a Telescope?

Stars in a telescope are probably the most beautiful sight to see in the clear night sky. What you can see in the sky is not even close to what is actually happening there. What is revealed to our eyes is a very diminished past of our universe. Therefore, when it comes to the stars, a person usually either has an image of bright dots in the sky, or something very reminiscent of our Sun floating in the depths of space. So, let’s take a closer look at how do stars look through telescope.


Observing Stars in a Telescope

In fact, most of the stars are these “boring” gas, brightly glowing balls. But there is something incredible in the vastness of space. Even though to us, it looks as a small and dim dot in the sky. This is where the telescope comes in, with which you can get a few hundred kilometers closer to the real picture of space.

Nearly everyone can imagine what do stars look like in space up close, but I’ll try to describe it from a more scientific view.

Things are upside down

Many people who first encounter such an optical instrument as a telescope will be greatly surprised to find that the image is reversed or mirrored. One might even think that the telescope is malfunctioning. However, this is far from the actual case. It is important to understand that the correct mirror or inverted image is determined by a number of design features of the telescope itself. Let’s understand why a telescope produces an inverted image?

The main reason a telescope turns the image upside down is due to the design features of its main elements, the lenses. When converting the light beams obtained an upside-down picture because the collecting lens makes two crossed from two parallel rays. If the rays are crossed once (when using one lens), the image comes out inverted.

How important is it that the image is upside down? There is no up and down in space, and when observing astronomical objects, it doesn’t really matter if the telescope is straight or upside down.

For example, the star Sirius is probably not the object you observe every day. And if you see this star, it is unlikely that you can accurately determine whether its image is upside down.

Nevertheless, in some cases, the “correctness” of the image is important, especially when observing terrestrial objects. In such situations, you can install an additional rotating prism on the telescope, which will correct the image.

sirius star

There are more stars than we think

The question of how stars can be seen through a telescope is one of the major questions for those new to astronomy.

A telescope is an instrument made up of many parts, and if you know how to use it, observing the celestial bodies will be one of the most exciting adventures of your life. One of the brightest luminaries available for observation is the Sun. The Sun can be viewed on any clear day, but it is important to remember to use special protective filters for the telescope lens and viewfinder.

If you want to get acquainted with objects of the solar system, a refractor telescope with an objective of 70-90 mm will be enough for you at the beginning. But even with the most professional telescope, you will not be able to observe ultra-cold brown dwarfs, because they do not shine at all. There are much more stars than we think, and even a telescope cannot really help us to observe everything.

If we were nearby, we would probably just see a dark ball overlapping the starry sky. And, if the distance from us to the star was the same as the distance from Earth to the Sun, we probably wouldn’t know we were passing a star at all!

Stars come in lots of colors and sizes

What does a star look like and what is the real color of a star? In fact, colors can be quite different. As a rule, visually on the celestial sphere, we distinguish between white and red luminaries.

Although many people think that stellar objects are white, in reality, they are not. They come in white, blue, yellow, orange, and red. The glow of stars in the sky is a very beautiful and mysterious phenomenon.

For example, the Sun has a comparably low surface temperature (10 000 F) and a corresponding yellow color. In contrast, a much bigger and hotter (20 000 F) Rigel has white-blue color.

Why do stars have different colors?

First, the Earth’s atmosphere distorts the real colors of stars. Secondly, it seems to us that the radiation of stellar bodies is white because of our perception. This is mainly due to human physical abilities. Because there are receptors in the retina of our eyes that are responsible for color vision. The weaker the impulse, the dimmer the light we see.

Surprisingly, the varied colors of stars are not so much due to their composition as to their temperature. As it turns out, heating ionizes certain elements, thereby hiding them.

Even the most advanced telescope will not allow you to see the star to its fullest extent. At most, what you can see are star clusters and double stars.

Star clusters are divided into two types: globular and diffuse. A globular cluster looks like a round, foggy spot that, when viewed with an average telescope, begins to break up into stars. The number of stars in globular clusters is very large and can reach several million. Scattered clusters, on the other hand, are piles of stars, often of irregular shape. One of the most famous scattered clusters visible to the naked eye is the Pleiades in the constellation of Taurus.

One of the most beautiful binary stars is Albireo in the Swan constellation. To the naked eye, Albireo looks like a single star, but just look through a telescope and you will see two bright points of different colors, orange and bluish. By the way, all stars are visible as dots through a telescope because of the enormous distance. All except the Sun.

Diffraction spikes

Diffraction spikes are lines emanating from bright light sources, causing the so-called starburst effect or solar stars in photographs and in vision. These are artifacts caused by light scattering around the secondary mirror support vanes in reflecting telescopes or the edges of non-circular camera apertures, and around the eyelashes and eyelids in the eye.

In the vast majority of reflecting telescope designs, the secondary mirror must be positioned on the central axis of the telescope and therefore must be held in place by spacers inside the telescope tube. No matter how good these support rods are, they diffract the incident light from the star you study, and this manifests as diffraction peaks, which are the Fourier transform of the support rods. The spikes represent the loss of light that may have been used to image the star.

Although diffraction spikes can obscure parts of a photograph and are undesirable in a professional context, some amateur astronomers love the visual effect they give to bright stars.


Let’s consolidate the information and answer the most popular questions:

Why do stars look like rings in a telescope?

There are two reasons for that:

Diffraction: since the aperture of the telescope is limited a point source is mapped to an image with a little disk surrounded by rings.

The atmosphere also causes distortions: not every part of the aperture has a plumb of air in front of it of equal temperature, and temperature influences density and thus refraction index. The result is that the atmosphere acts as an ever-changing floppy weak bad lens that distorts the image.

Why do stars look like donuts in my telescope?

This is because the image is not in focus. You’re probably seeing the shadow of the secondary mirror. You should have a knob near the eyepiece for adjusting focus.

Why can’t I see anything in my telescope?

In order to observe the night sky through a telescope, you should adjust the focal length and other parameters. It can also be due to damage to the lens, mirrors and common defects.

How does the moon look through a telescope?

When you look at the moon through a telescope, you can see nearly all of the major features. The moon is a great object to observe because it is big and bright and has a lot of detail. You can use a telescope during the day, but you will have to pick from a smaller range of objects that are visible. You can also look at the sun, but you need to be careful.

What Do Stars Look Like Up Close?

Watching the stars through a telescope is truly mesmerizing. You can consider yourself the happiest person on earth simply because you have the opportunity to observe the beautiful night sky, galaxies, nebulae, planets, and star clusters.

What stars were you able to see with your telescope? Do they look like rings? Share your thoughts about the topic in the comments below.

About Valery Johnson

Hi, I am Valery and I love nature, the universe and the starry sky. Together with my friend Michael we share our practical knowledge in the field of astronomy and nature observation. We also test different optical instruments to see the strengths and weaknesses of different models. Very often we travel around our country, so we have the opportunity to test optics in different conditions and different seasons. Welcome to Michael's and my blog and we hope you find useful and practical information for yourself.

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