Best Planetary Telescopes

All telescopes can be used to view planets. Telescopes gather light and they don’t care where it comes from. The eyepieces provide magnification to let you see more detail than you can see the naked eye. But there is a difference in seeing a planet and seeing it in the greatest detail with the sharpest image.

I will discuss the factors to take into account and then make some suggestions. And, naturally, the best planetary scopes are very expensive. I won’t be calling out those $10,000+ beauties. Those are more for observatories and professional astronomers. I will focus on great planetary scopes that are well within the hobby market price range.

I won’t be spending much time comparing and contrasting the different types of optical tubes including refractors, Newtonian reflectors, Schmidt-Cassegrain, or Maksutov-Cassegrain designs.

I won’t be discussing computerized, PushTo or GoTo mounts as they are not really a factor here. Planets are pretty easy to find. Mercury, Venus, Mars, Jupiter, and Saturn can be seen naked eye, so computer assistance is not needed to find them. However, the GoTo mount’s ability to track the target can be beneficial as you drive up the magnification. A planet viewed at 300X will pass through the field of view of a manually tracked scope fairly quickly.

Key Features To Look For In a Planetary Telescope

Aperture is the diameter of the front lens or rear mirror of the optical tube assembly stated in millimeters or inches. When looking at deep sky objects we want as much aperture as possible so we can see dim things. However, when observing planets we are looking for resolution, the ability of the scope to resolve small details. 

For example, a 6” Newtonian optical tube assembly will have a resolving power of approximately .8 arc seconds. A 12” Newtonian will have a resolving power of about .4 arc seconds. This means that the larger aperture will allow us to see smaller details and that is very desirable for planetary observing. 

Keep in mind that small is relative here. We are talking about planets that are hundreds of millions of miles away. In practical terms, when observing planets, we measure them in angles rather than miles using angle measurements of degrees, arc minutes, and arc seconds. One degree is made up of 60 arc minutes, 60’. Each arc minute is made up of 60 arc seconds, 60”. 

The apparent size of the full moon is about ½ degree or 30 arc minutes or 1800 arc seconds. A difference of .4 arc seconds between the two scopes above is hardly significant. 

Saturn, as viewed from the Earth is between 15 and 20 arc seconds wide, depending on where we are in our relative orbits around the Sun. So a resolution difference of .4 arc seconds is a significant factor if you are trying to resolve as much detail as possible on Saturn. 

The same will hold for any type of optical tube design. The larger the aperture the greater the resolving power. 

Planets are targets that benefit from high magnification when atmospheric conditions are good. The greater the aperture the more light that is gathered, the higher you are likely to be able to take the magnification to see greater details. Note that the atmosphere is often the limiting factor here. 

We talk about the “seeing” conditions when we are out observing. Seeing refers to the turbulence of the atmosphere. When the air is calm large aperture allows us to apply high magnification while maintaining a quality image. When the air is turbulent, magnification and image quality may be limited regardless of aperture. 

Keep in mind that larger the aperture the larger and heavier the optical tube, regardless of the type of optical tube being considered. We need to balance this against the capacity of the mount to hold it and our ability to move it around. 

Unless you are mounting this telescope in a stationary observatory, size and weight are serious considerations. A big optical tube with great resolving power that you can’t handle is worthless. So a balance needs to be taken into consideration. 

And, of course, the larger the aperture the higher the cost. Big optical tubes can require big mounts and the costs can pile up fast. A nice 16” Meade LX600 SCT will provide very nice planetary images with .28 arc second resolution. But it costs almost $20,000 and weighs over 220 pounds. Most often, these are mounted on piers inside an observatory. This is not the typical hobby telescope, but if you have the money and location, this might be a good choice.

Mathematically, this is the focal length divided by the aperture. A low focal ration optical tube will be shorter than a high focal ratio optical tube with the same aperture. 

For planetary work we would have a preference for higher focal ratio optical tubes, say over F8. The higher the focal ratio the straighter the optical path for the light rays which introduces less distortion. This has to do with how much work the eyepiece has to do to deliver a clear crisp image across the entire image. The lower the focal ratio the more complex the eyepieces become to provide a good image.

Again, size and weight become factors as a high focal ratio optical tube will be longer. A longer optical tube places more strain on the mount to remain steady. A long optical tube will tend to wobble more in a breeze if the mount is not strong enough to hold it steady. So the mount gets bigger and heavier and more expensive as we strive for that optimal planetary telescope system. 

This is mostly related to refractor type optical tubes. Without going into a lot of detail, lower focal ratio refractors tend to show more chromatic aberration which can introduce false colors or color rings around bright objects like planets. For the average person, this may not be a huge issue, but if you are looking for the best planetary refractor, you need to take this into account. An F12 refractor will have a lot less chromatic aberration than an F5 refractor.

Refractors come in two general types, achromatic and apochromatic. In simple terms the achromatic typically has two objective lenses that help to reduce chromatic aberration but do not completely eliminate it. Most introductory telescopes are of this type and do an adequate job for most purposes.

Apochromatic refractors usually add a third lens in the object and often exotic types of glass to eliminate chromatic aberration as much as possible. These are preferred by astrophotographers and demanding visual observers. They are heavier and much more expensive, but for someone looking for the optimum refractor planetary telescope, this is what you want. 

When it comes to large apertures, the Newtonian reflectors and catadioptric scopes take over. Refractors over 6 inches are not common in the hobby market and over 8 inch refractors are typically for observatories.

Best Telescope Recommendations For Viewing Planets

As stated in the beginning, any telescope can be used to view planets. What I will be highlighting are telescopes that would be of most interest to astronomy hobbyists, not observatories. I will include examples of refractors, Newtonian reflectors, SCTs, and MCTs. And I will offer examples across several price ranges so you can pick that best planetary telescope that works within your budget and size goals.

Under $500

1. Orion SkyQuest XT8

Price – $399.99

The XT8 is an 8”/203 mm F5.9 Newtonian reflector on a Dobsonian mount. When it comes to aperture per dollar, the Dobsonian design is the leader in the industry and the Orion XT8 is probably among the most popular in its class. It balances aperture, size, and weight very nicely at a price that makes it a very attractive all-around scope as well as a value price planetary scope. The AltAz design of the Dobsonian mount makes it super simple to use.

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Orion 8945 SkyQuest XT8 Classic Dobsonian Telescope

2. Celestron Omni XLT 120

Price – Price not available

This 102 mm/4 inch F9.8 achromatic refractor will provide very good images at a great price. Its size and weight will make it very manageable and it will travel easily for trips to remote sites.

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Celestron Omni XLT 120 Reflector Telescope

Between $500 to $1000

3. Meade ETX 125 F15 Maksutov-Cassegrain GoTo

Price – $699.00

With its high focal ratio, the 5” ETX 125 has an excellent reputation as a planetary scope. The robotic features will find and track planets and deep sky objects. Its compact package makes it easy to move, easy to store and easy for travel.

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Meade Instruments – ETX125 Observer – 127mm Aperture Maksutov-Cassegrain (MAK) Computerized GoTo Astronomy Telescope with AudioStar 30,000+ Object-Database & Guided Audio Tours - EQ Plate Tilt Plate

4. Zhumell Z12

Price – $1,655.35

The Zhumell Z12 Dobsonian reflector offers big aperture, ease of use, and twice the resolving power of an 8” scope. It gathers 225% of an 8” scope allowing you to apply more magnification. While it weighs over 80 pounds it can be moved in two pieces or you can move it with a hand truck to easily take it to your observing site.

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Zhumell Z12 Deluxe Dobsonian Reflector Telescope

5. Meade LX65 8" ACF

Price – $2,779.32

What this scope gives up in aperture to the manual Dobsonian 12” it brings back in a higher focal ratio and robotic operation. If your interests expand beyond planets, the LX65 mount will find the deep sky objects for you and track them just as it tracks planets. 

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Meade Instruments 228004 Lx65 8' ACF Computerized Telescope with AudioStar

Over $1000

6. Orion XX14G Dobsonian with full GoTo

Price – $3,342.23

The large aperture of this scope will provide resolution down to .33 arc seconds as well as allowing you to reach very high levels of magnification when the atmosphere is calm. At high magnification the tracking of the mount becomes quite valuable. And the truss design of this optical tube allows it to be dismantled for easier storage and transport.

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Orion 8964 SkyQuest XX14g GoTo Truss Tube Dobsonian Telescope

7. Celestron Evolution 9.25” F10 Edge SCT

Price – Price not available

This system features a GoTo equatorial mount that will provide excellent tracking for visual and astrophotography of planets and deep sky objects. The HD optics provide better and sharper images than Celestron’s standard SCT optical tubes.

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Celestron CGEM II 925 EdgeHD Telescope, 9.25in, 12018

Summary

Any telescope can be used to see planets. But when we want the very best images then we go for large aperture or long focal ratios and, where possible, both. However, these can lead to either very large or very heavy and expensive telescopes. So take these factors into serious consideration when you are shopping for your optimized planet observing telescope. And remember that these scopes will also give you excellent views of deep sky objects where, again, aperture is king.