What makes a good planetary telescope?
Planets are small and bright, so good planetary views come from high-quality optics, a steady mount and the ability to use fairly high magnification. Aperture helps, but contrast, sharpness and stable atmospheric conditions (called seeing) matter as much. A smaller telescope with clean, well-made optics can often outperform a larger, poorer one on planets.
Which type of telescope is best for planets and moons?
Several designs work well.
Refractors
Good refractors give sharp, high-contrast images with no obstruction in the light path. Apochromatic (APO) refractors control color fringing very well but get expensive as size grows. Inexpensive achromats can show some color fringing around bright planets, though many beginners find the views perfectly enjoyable.
Maksutov-Cassegrains
Their long focal length and good contrast make them popular for planets and the Moon. They are compact and fairly low-maintenance, though they are slower to cool and offer less aperture per dollar.
Schmidt-Cassegrains
Models such as 6 and 8 inch SCTs are widely recommended as all-rounders. They give high magnification in a compact tube, and computerized mounts help with finding and tracking. See best GoTo telescopes.
Dobsonians and Newtonians
Larger Dobsonians collect plenty of light and can give excellent planetary views, particularly at 6 to 10 inches, as long as the optics are well collimated and have cooled down. Because Dobsonians are not motorized, you have to nudge the scope to keep up with the planet, which takes practice at high power.
What size telescope to see Saturn’s rings?
Saturn’s rings can be seen as a distinct feature in very small telescopes at roughly 30x to 50x. A 4-inch (100 mm) scope shows them more clearly, along with the Cassini Division on a steady night in a good scope. A larger aperture and higher magnification bring out more subtle detail.
What to expect from each planet
- Jupiter: cloud belts, the Great Red Spot at times, and the four Galilean moons are visible in small scopes.
- Saturn: the rings and the largest moon, Titan, are visible in small scopes.
- Mars: often a small orange disk; surface features are best seen near opposition, when Mars is closest, and need good optics and steady air.
- Venus: shows phases like the Moon, but little surface detail.
- Mercury, Uranus and Neptune: Mercury is small and low near the horizon; Uranus and Neptune appear as tiny disks and need larger scopes to show much.
Planets look smaller than most beginners expect, and they do not appear in the vivid color of spacecraft photos.
What to avoid when buying
- Scopes marketed on huge magnification, since atmospheric limits cap useful magnification in practice
- Wobbly mounts, which make high-power viewing frustrating
- Tiny, low-quality eyepieces and Barlow lenses
- Buying only on aperture while ignoring optical quality
See our guide on how to pick a good telescope for more.
What is the best telescope for kids?
A lightweight, simple, sturdy scope is best for children, such as a small tabletop Dobsonian or a short refractor with a stable mount. Easy setup matters more than features. Binoculars can also be a good start; see best telescope for watching stars.
Eyepieces, Barlows and filters
A few good eyepieces cover most needs: a low-power one for finding objects and a medium-to-high-power one for planets. A Barlow lens multiplies the power of each eyepiece. Colored filters can bring out some planetary features, though the benefit is modest and depends on the filter, planet and conditions.
Tips for sharper planet views
- Let the telescope cool to outside temperature.
- Observe when the planet is high in the sky, where there is less air to look through.
- Be patient: moments of steady air let fine detail pop out briefly.
- Increase magnification gradually, and drop back down if the image turns soft.
- Keep the optics clean and collimated, if your scope needs it.
Budget
Good planetary scopes range from a modest starter refractor or Dobsonian up to more costly SCTs and APO refractors. See how much a good telescope costs for general price tiers, and best telescope for deep space viewing if you also care about galaxies and nebulae.