What Can You See With 100mm Telescope?




What Can You See With A 100 M Telescope

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With a 100mm telescope, you can see all the planets except Pluto, the moon, stars, and nebulas. This scope can clearly capture the Moon’s craters and geological features very clearly and with high definition. You can also see galaxies with this scope.

When purchasing any kind, it is critical to understand exactly what you are getting. As a beginner, choosing a telescope can be difficult because most manufacturers just show you how they seem from the exterior, while others mention a long list of features and numbers that are meaningless to you. 

This is completely ineffective. To better grasp what a 100mm telescope can do, this article will help you understand what you can anticipate from it.

What Does 100mm Mean?

When a telescope is referred to as a 100mm telescope, it refers to the device’s aperture, which is measured in millimeters and is expressed as a number.

The aperture of a telescope is defined as the size (diameter) of the larger frontal lens of the telescope. This is the lens that is responsible for capturing light in your telescope. 

More light generally translates into a better, clearer image, so a larger aperture is nearly always preferable, although it comes at the expense of a greater price.

To accommodate astronomers’ preference for the metric system, the aperture is most commonly stated in millimeters. In the instance of 100mm, this corresponds to around 3.9 inches in length.

How Far Can 100m Telescopes See?

When using a 100mm telescope, the maximum magnitude achieved is 13.6. A value known as the maximum magnitude can be derived by using the aperture of a telescope as a starting point. 

This value can be compared to the limiting magnitude of a celestial body, which is essentially the brightness of an object in the sky and can be calculated. 

Any object with a magnitude less than the maximum magnitude of the telescope should be visible. Any object that is far has a greater magnitude than the telescope will not be visible.

For instance, Pluto has a magnitude of 13.65 while Mars has a magnitude of -1.52

100mm Telescope:  What Can You See With One?

The 100mm telescope is an ideal telescope for stargazing. If you are a beginning astronomer or have some experience in astronomy, you will greatly benefit from a 1000mm telescope.

The level of detail you’ll see on your target with this telescope will astound you. There are a few additional variables that determine what you can view through your telescope lens and the quality of the image.

The exact calculations can only be determined by knowing the telescope’s focal length, magnification, and even then, differences between telescopes can be perceived due to the quality of the lenses and mirrors or even outside variables like weather conditions.

But for the most part, an approximation can be made using only the aperture as it is the most important variable.

Here’s what you can see with a 100mm telescope:

The Moon

The Moon looks amazing in these telescopes. They are more than enough to capture its craters and geological features very clearly and with high definition. Don’t expect to see, however, the minor objects. 


As previously stated, any star with a limiting magnitude of less than 13.6 should be visible to you if you are looking in the right direction. The sky is filled with hundreds of stars that are not visible to the human eye, including all of the constellations.

Nebulae and galaxies are examples of astronomical phenomena.

Nebulas are a fantastic target for any telescope of any size. You should be able to view some of the more prominent ones, such as the Orion Nebula.

In addition, if you can travel to specific locations on Earth, the Milky Way delivers a spectacular display.

For this type of object, there is a significant gap between what can be seen with the naked eye or even with a telescope and what can be captured by a camera utilizing long exposure photography, making it an excellent opportunity to learn about astrophotography if you have a good camera


With a 100mm telescope, you can see mercury. Given that it does not wander significantly from the Sun and is frequently low on the horizon, this planet is among the most difficult to view.

Its larger elongation is merely 28° longer than its shorter counterpart.


With a 100mm telescope, you can see Venus with its distinct stages and some atmospheric changes. Early morning or early evening are the best times of the year to watch Venus, depending on the season of the year. 

Because of how closely it orbits the sun, it is the brightest of the planets. This planet can be studied with a telescope throughout the day, provided that you are extra cautious to ensure that your field of vision does not get too close to the sun while doing so.

Venus, like the moon, goes through phases, and many amateur astronomers aim to catch images of each phase that this planet goes through to document it.


With a 100mm telescope, you can see Mars, the planet Mars has visible poles and key features.

Mars is visible to the naked eye all of the time because it is so bright. It has a reddish hue to it and generally has the appearance of a star; however, it does not twinkle as much as stars do.

A significant number of the planet’s surface features can be seen even with a small telescope. Every two years, for approximately two months, Mars is at its closest point to the Earth.

There is the best time of year to take your 100mm telescope outside and study the red planet with it. You might even be able to view the polar caps if you put in enough time and effort.


With a 100mm telescope, you may see some of the identifiable features of Jupiter.

A telescopic object such as this planet is one of the simplest to observe, and it does not necessitate the use of an expensive or huge optical apparatus. 

Jupiter is frequently visible for a significant portion of the nighttime sky during the entire year. Once every 13 months, this planet moves into a new constellation in the sky, making it quite straightforward to monitor over a long duration if you want to do so. 

Jupiter will appear majestic, and you should be able to distinguish some of the four Galilean moons from one another. 


With a 100mm telescope, you can see Saturn and its rings.

When it comes to telescopic targets, the most impressive is the ringed planet, which is sometimes cited as the reason why so many people fall in love with stargazing.

Saturn is the planet that is easiest to observe via a telescope. 

With a large telescope focal length, you can see a great deal of detail, including the many layers of clouds. You might even be able to glimpse a few Saturnian moons, depending on the quality of your telescope. 

Saturn is a great place to start if you’re new to astronomy and have a 100mm telescope to use for practice.


With a 100mm telescope, you can see Uranus as only a dot.

Uranus is very far. The use of a 100mm telescope and the presence of a dark sky are required to observe it well. 

You will also need to be aware of the planet’s specific location and the stars in its immediate vicinity, as it is quite simple to confuse the planet with background stars. 

It is simply a faint dot with a blueish color that you can see even in the greatest viewing conditions 


With a 100mm telescope, you can see Neptune. Only a dot can be seen for this planet, and good viewing conditions are required.

The gas giant is located at a great distance from the Sun and requires a powerful telescope (200 to 300 times magnification) to be observed. Because of the presence of methane in the upper atmosphere, a large telescope may be able to see a very small disc with a bluish coloration.


With the 100mm telescope, you cannot see pluto. The dwarf planet is a very long way away from earth. 

To see Pluto, you’ll need a telescope with an aperture of at least 200mm at the very least. Even in that case, Pluto will appear to be a small star. 

Despite this, many amateur astronomers are happy to have observed this planet because it is a truly difficult subject to observe.

The Pros and Cons Of 100mm Scopes

The Pros

100mm scopes are compact and light, making them convenient to carry. As a result, if your primary scope is too large, they make good secondary “carry-on” equipment.

The other advantage is that you do not have to break the bank to obtain one because the 100mm Scope is reasonably priced.

Furthermore, they are available in a variety of designs and models. Every reputable manufacturer offers at least one product in this category.

The Cons

One of the disadvantages of the 100mm telescopes is that they lack the more advanced capabilities of larger scopes.

Another disadvantage of the 100 mm is that there are only a limited number of magnification options available. One of the most significant disadvantages of small aperture lenses is that they do not permit the use of high magnification eyepieces.

It makes no difference if you try to use a magnification of 250x. Because your telescope can only gather a limited amount of light, it will appear to be the same magnification as 100x magnification. 

The 100 mm telescopes can be outgrown in a very short period. If you enjoy stargazing, you’ll want to get to the top of the mountain as soon as possible.

Who are 100mm Scopes Good For?

In terms of entry-level telescopes, 100mm models fall somewhere in the middle. 

The 100mm telescopes are recommended for newcomers who want the most value for their money when purchasing their first astronomical viewing instrument. They’re also a good option for teenagers.

100mm Telescopes Suggestions

The Orion SkyScanner 100 mm

100mm Recommendation
The Orion SkyScanner 100 mm

The Orion SkyScanner 100 mm is well-suited for a variety of applications.

Its aperture is on the small side for a Newtonian on a Dobsonian-style mount, but it’s just the right size for portability and viewing. 

The excellent optics will not only pique a child’s interest in astronomy, but the breathtaking views and the ability to mount the tube on a variety of mounts will help to maintain that interest.

The tabletop telescope is a fantastic choice for any buyer, whether they are children or adults. It’s an excellent starter telescope because it’s simple to use, comes pre-assembled, and is built with quality in mind.

More experienced users may find the small aperture restricting, but they will appreciate the convenience of the grab-and-go design and the numerous mounting options available with this platform.


The Celestron Inspire 102AZ Refractor

100mm Recommendation
The Celestron Inspire 102AZ Refractor

For any aspiring astronomers, this is an excellent first telescope.

While the Celestron Inspire 102AZ telescope is an excellent choice for beginning astronomers or those on a tight budget, it is also a great choice for those seeking a complete package that includes more accessories than the majority of starter telescope packages.

For basic astrophotography, the Inspire 102AZ is equipped with a 1.25-inch fitting and a 90-degree erect image diagonal, which makes it suitable for both terrestrial and celestial views. 

It also includes two eyepieces (20mm and 10mm), an accessory tray, a red LED flashlight, and a StarPointer Pro finderscope in addition to a smartphone adapter. Because of the refractor’s focal ratio, the Inspire 102AZ is only suitable for photography with short exposure times.

The presence of a degree of false color and blurring in the field of view was observed during our experiments. The latter issue can be easily resolved by using a carefully chosen set of eyepieces, so we recommend investing in additional eyepieces to make the most of the Inspire 102AZ’s optical system and ensure that it is reflected in your photographs.

In contrast, although the false color is to be expected in telescopes at this price point, it did not detract from the overall experience. It is suitable for young children or teenagers because it is a good entry-level telescope.


The most important thing is to try to study them without being distracted by turbulence in the atmosphere because planets require higher magnification than stars.

The smallest amount of turbulence can cause the image to become blurry, and the finer details will no longer be visible.

It is possible to see the planets in the night sky with the naked eye, even in low light conditions. They usually have a slightly distinct appearance than stars, and they do not twinkle nearly as much. 

Even if you live in a city where there is a lot of light pollution, you should be able to detect them rather quickly. We also have an article talking about what a 70mm will see if you are looking for a cheaper alternative.

Please be careful and use at your own risk
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