What Can You See With a Telescope

What Can You See with a Telescope?

Now, if you’re buying a telescope for the first time, the first question you’re likely to ask is exactly what can you see with a telescope? And, why exactly? Because one, telescopes are quite expensive and two, you’ll be eager to observe the heavens beyond what your normal eyes can see.

Telescopes are truly phenomenal tools that let us explore the wonders of the universe right from the comfort of our homes. They take us into the vast unknown to explore the beauty of the stars, planets, nebula, and the various galaxies.

But, despite all these, you need to note that a telescope isn’t just a telescope. Some instruments have larger and more advanced mirrors that let you see distant objects that are millions of light-years away. Others have less powerful mirrors that display the same distant objects as dots.


What Can You See with a Telescope: Step-by-Step Guide


For that reason, you need to understand that how much you’ll expect to see with your telescope will depend on several factors. One of those is obviously the type of telescope you’re using. Since each telescope has different technical specifications, these specs will have a huge impact on how much you’ll expect to see.

Other factors include your level of experience, atmospheric conditions, your eyesight, and the optical quality of your telescope. So, with that said, we’ll now get to our main topic. But, before we do that, we’d like to begin by discussing those factors that affect what or how much you can see in your telescope.


What Determines How Much You Can See With a Telescope?


Just as we’ve mentioned earlier, before we get to what you can see with a telescope, we need to first understand those factors that affect what you see. Now, if you’re a reseller selling telescopes, you’ll definitely expect your customers to ask questions such as “Will I view the planets with my telescope” or “Will I see Pluto right from the comfort of my balcony

To answer such questions, you’ll definitely tell them No! or Yes! or Maybe! Why? Because what you’re able to see is determined by various factors. So, which are these factors?

1. Size and Type of Telescope


Although these terms are quite disturbing to interpret, the first thing you need to think of when getting a telescope is to understand the different types that are available. This is important because each type of telescope has its strengths and weaknesses that determine how much you see. So, the three different types of telescopes are:

  • Refractor Telescopes: That use lenses to focus light
  • Reflector Telescopes: Use mirrors to focus light
  • Compound or Catadioptric Telescopes: Use a combination of mirrors and lenses to focus light


  • Refractor Telescopes

Refractor telescopes are ideal if you’re looking to view objects in the galaxy with high contrast and clarity. Now, the reason why these telescopes have high contrast is the fact that they don’t have secondary mirrors as it’s the case with Newtonian (reflector) and compound telescopes.

This means that light from the lens travels in a straight line to the eyepiece giving you a decent 93% view of an object in outer space. Therefore, under high magnification, these telescopes can view objects that are far in the lunar or solar eclipse with high-quality details. This optical advantage makes a small refractor telescope view objects with the same details as much bigger reflector telescopes.

But, despite their benefits, these telescopes have their downsides. One of them is the high cost of the lenses that increases per inch of aperture. This means that the larger the diameter of the aperture, the higher the price of the telescope.

Now, the aperture is very important when determining the quality of the image you’re viewing. The bigger the aperture, the brighter the object will be hence the better the quality of the image. Since refractor telescopes get pricier with an increase in aperture size, you’ll have to stick to a telescope with a small aperture to avoid spending too much money. By trading price with quality, you’ll hence view objects that are too faint and dull.

Another drawback with refractor telescopes is that they’re susceptible to chromatic aberration. So, to avoid this, you have to stick two or three lenses together, which again bumps up the cost.

  • Reflector (Newtonian) Telescopes

Also known as the Newtonian telescopes these types of telescopes are basically the best for beginners due to one thing—they use mirrors that are quite cheap to procure and manufacture than lenses. When it comes to viewing the deep dark space, these telescopes are also the best as they can afford to have huge apertures due to the low cost of mirrors.

Now, when it comes to the working mechanism, reflector telescopes rely on a primary mirror that sends lights to the secondary mirror. The secondary mirror is placed near the OTA at an angle of 45° to the primary mirror. So, with this setup, light from the primary mirror moves to the secondary mirror where it bounces to the eyepiece for you to see.

Since reflectors have large apertures and long focal lengths due to the reflected light from the primary to the secondary mirrors, these types of telescopes are the best for viewing deep sky objects such as the galactic structures and tendrils within the nebulae.

But, just like the refractor telescopes, reflector telescopes have their fine share of setbacks. One of them is the position of the OTA that makes it easier to accumulate dirt, dust, and pollen. Also, mirrors need to be recoated with aluminum every 10-20 years. These two setbacks mean that these telescopes demand regular maintenance, which is not the case with refractor telescopes.

Two, mirrors need regular collimation to keep them perfectly focused. Three, mirrors suffer from contrast and coma. You see, when light bounces from primary to secondary mirrors, it tends to lose contrast making it hard to view distant objects with finer details.

Lastly, reflector telescopes are much heavier and bulkier to carry. In fact, some models such as the Dobsonians require disassembly to allow easy transportation.

  • Catadioptric (Compound) Telescopes

Lastly, we have Catadioptric telescopes. These ones tend to mash the features of reflector and refractor telescopes into one improved telescope. By mixing mirrors and lenses, these telescopes end up with a very short optical tube and a much longer focal length.

This advantage allows them to offer a high level of magnification with larger apertures that let in enormous light enough to view distant objects. With Catadioptric telescopes, light enters through the aspheric correcting plate to a spherical primary mirror mounted at the back of the tube. It’s then reflected back to a secondary mirror mounted just behind the front corrector plate before it bounces back at the back of the tube through an opening at the rear.

The best thing about this type of optical configuration is that it reduces the size of this telescope to make it compact and lighter. It also helps to correct some problems previously suffered by reflector and refractor telescopes such as comma, vibrations, chromatic aberration, and distortion.

With large apertures and long focal lengths, Catadioptric telescopes have a wider field of view that makes them the best for viewing near and distant images of the dark skies and the galaxies.

Any setbacks? Of course, yes. Catadioptric telescopes are very expensive and two, the use of a secondary mirror exposes them to the same problem suffered by reflector telescopes.


2. Magnification


The second factor that’s likely to determine what you can see with a telescope is magnification. You see, for you to view distant images in the dark-skies, you need to magnify them to make them appear larger.

Now, in most cases, the magnification of a telescope is calculated by dividing the telescope’s focal length and the eyepiece focal length. So, assuming the telescope has a focal length of 1000mm and the eyepiece has a focal length of 10mm, then it means the telescope has a magnification of (1000 ÷ 10 = 100mm) 100x.

Assuming the telescope has an eyepiece focal length of 25mm, then it means the magnification will be (1000mm ÷ 25mm = 40x) 40x. So, with these two calculations, it’s clear that the lower the eyepiece focal length, the higher the magnification.


3. Focal Length


Measured in millimeters, the focal length is the distance between the capture lens and the eyepiece. Unlike the case with aperture where larger is always better, the size of the focal length will have varying effects on what you can see. For instance, a shorter focal length will give you a wide field of view while a longer focal length will give you more details when viewing distant objects.


4. Aperture


Although all the other factors we’ve discussed play a huge role in what you can see with a telescope, the aperture is what makes the ultimate difference. Aperture refers to the diameter of the objective or frontal lens of your instrument. It’s the one responsible for capturing the light that enters the telescope from space.

Unlike the focal length, the diameter of the aperture is the one that defines how much you can see. The larger the diameter, the clearer the images will be. Therefore, if you want to view the moon, Cassini divisions in Saturn’s rings, ice caps of Mars, sunspot structure, and the Galilean moons of Jupiter, then a 4” – 5” aperture will be ideal.

On the other hand, if you want to view deep-sky objects such as the nine moons of Saturn, cloud belts of Jupiter, double stars at least 1” apart, details on brighter nebulae, and more stars in globular clusters, then you need a telescope with an aperture diameter of more than 6”.


5. Filters


Another factor that determines what you can see with a telescope is the filters. Now, filters are special attachments that are added to the mirror of the eyepiece to block certain light wavelengths to improve image quality and clarity.

In most cases, filters come in different types depending on what you want to see. There are lunar filters, light pollution filters, colored filters, and filters specifically designed for viewing dark-sky objects. So, depending on what you want to view, filters are special attachments that exclude certain wavelengths to emphasize those wavelengths that bring out the best clarity and contrast of what you’re viewing.


6. Time and Place


The last factor we’ll discuss before we dive into what you can view with a telescope is deciding the proper time and place to view the dark skies. Although it’s said that a telescope can view anything right from the comfort of your balcony, the time and the location you’re viewing from can have a huge significance.

For instance, if you’re viewing objects under an extremely dark night, then you’ll manage to view more objects with finer details. Conversely, if you’re viewing objects in a light-polluted area (such as a city with bright street lights), the objects you’re viewing will appear dim with fewer details.

Meteorological phenomena such as dust storms, hailstorms, and too many clouds are other factors that can block your view. Other than that, seasonality can also determine what you can see as certain objects such as stars, galaxies, nebulae, and other distant objects are visible at a certain time of year.

Your location can also tell what you can and what you can’t see with a telescope. For instance, people in the Northern Hemisphere will have a different view of the universe as compared to those in the Southern Hemisphere.


6 Things You’ll Expect to See in a Telescope


Now that we’ve discussed those factors that affect how much you can see, this guide will now get straight to the point to list the different kinds of objects you’re able to view with your telescope.


1. The Sun


One of the fun things you can view with a telescope is the sun. In most cases, the sun is considered the only star that’s closest to the earth. It’s also the only object in the solar system that is viewable in broad daytime.

Now, why do astronomers view the sun? Well, the main reason why people view the sun is to look for sunspots. Depending on the power of the telescope you’re using, sunspots will be quite fun to view as they keep changing after every 11-years of their cycle. They also reveal the sun’s rotation, which occurs with a frequency of 25 days.

Now, when viewing the sun, you need to observe extreme caution. You need to use the proper solar filters to avoid damaging the lenses on your telescopes and worse, your eyes.


2. The Moon


One of the objects you always gaze at when you’re having sleepless nights is the moon. When you view it with your naked eyes, what you see is a black and white circle. But, if you view the moon with a telescope, what you see is a totally different object.

The craters, the hills, and the mountains are all interesting points that are visible when you view the moon with a telescope. The best thing about the moon is that it’s visible even by a small kids’ telescope. But, to have the perfect view of the moon, you need to wait until it forms a thin waxing crescent.

This way, the shadows will give you the best light and definition that will help you view the surface with more details. The worse time to view the moon is when it’s bright and full. Here, intense brightness will make it hard for you to see the details of the moon’s surface.


3. The Planets


Other than the sun and the moon, the next objects you’ll expect to see with a telescope are the planets. Although there are several of them, the only ones you’ll expect to see with finer details are Mars, Venus, Jupiter, and Saturn.

As for the case of Mars and Venus, these will appear as tiny circles with more details visible when they get to the closest approach to earth. As for Saturn and Jupiter, more of the surface details will be visible, which of course, makes astronomy fun and entertaining.

Jupiter, on its part, has lots of rich and interesting features to view. Using a blue filter, some of those features include the cloud belts, the famous giant vortex (red spot), and the four famous large moons that include Io, Callisto, Europe, and Ganymede.

Saturn, on the other hand, will not leave you disappointed. By using a yellow color filter, you’ll manage to see amazing features such as the Cassini Division between the rings, its striped belts and zones, and its largest moon—the Titan.


4. The Stars


Other than the planets, other fascinating objects you can view with a telescope are the stars. Now, if you happen to view the stars with your naked eyes, the highest number you can record is roughly 10,000. But, if you use a reflector telescope with a large aperture of around 14”, then you’ll be amazed to see over 50 million stars with finer details.

Now, a small telescope with a small aperture will display various star clusters as faint and fuzzy objects with indistinguishable light. But, if you use a more powerful instrument, it will manage to resolve tighter pairs while also revealing the difference in their colors. Some of the most interesting star clusters you’re able to view with a high-quality telescope include;

  • The Pleiades Cluster: This scattered cluster reveals a uniform pile of stars that are close together. When viewed through a powerful 150mm instrument, these stars appear like a swarm of bees that are densely clustered in one area. Although the stars are over a million, only 5 are prominent as most of their light magnitude tends to outshine the rest.
  • Omega Centauri: When viewed with naked eyes, the Omega Centauri appears like a faint fuzzy cloud containing many tiny stars. However, when viewed under a telescope, this cluster reveals a shiny ball of countless stars bound together by gravity. The stars appear larger with beautiful colors that resemble shards of glass.
  • The Jewel Box: This cluster consists of many stars that glow in different colors. What makes it amazing is the beautiful combination of colors, especially among the large stars, that make it resemble a jewel box.


5. The Galaxies


The galaxies are other interesting objects you can view with a telescope. However, since they’re millions of light-years away from our own Milky Way galaxy, most telescopes display them as small and faint objects.

However, if you’re lucky enough to own a powerful instrument, then you’ll manage to view some of the brightest galaxies such as the Andromeda galaxy. Covered with dust lanes, this galaxy is filled with trillions of stars, black holes, planets, and other celestial objects.

But, just as mentioned earlier, time and location can determine what you can see with a telescope. Therefore, to get the best view of the Andromeda galaxy, you have to be in the Northern hemisphere from August to February or Southern Hemisphere from October to December.


6. Nebulae


Nebulae are gaseous clouds that reside in the Milky Way galaxy. Viewing them with a telescope under very dark skies gives you the complete image of the nebulae, especially the Orion Nebula. Now, if you view the Orion Nebula with a telescope, what you’ll see are black and white textures of the tendrils, dust clouds, and many stars that swim within it.




As you can see, there is the infinite beauty and many wonders one can view in the deep-skies apart from the six we’ve mentioned. But, to enjoy these wonders, there are several factors you must consider. One of those is the type of telescope you’re using. Here, you must invest in a good telescope that has a large aperture to allow you to explore more of the deep skies.

Outside the telescope, you need to consider the time and place you’ll be viewing the universe from. You also need to consider the type of filters you’ll be using as well as ensure you’re in a location that has minimal light pollution.

So, whether you’re a professional or a beginner looking to get started in the astronomy journey, we believe that this insightful guide has given you everything you need to know when it comes to the question of “What can you see with a telescope”.

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