Looking at planets with a telescope is the reason for many beginners to purchase a telescope. The rings of Saturn, the red color of Mars or the moons of Jupiter: it all sounds magical. But what do you really see? In this blog post, we list realistic expectations, technical tips and helpful observing aids. Whether you're watching with your child or diving into the night sky for the first time yourself, you'll know exactly what to look for after reading.
What do you really see through a telescope?
Let's face it: you won't see color images like those from NASA or the James Webb Space Telescope. What you see depends on the telescope, the sky, your experience and, most of all, your expectations.
Still, there is much to admire:
- Jupiter shows its four largest moons as tiny points of light. In good conditions, you can see the cloud bands and sometimes the Great Red Spot.
- Saturn is impressive. The rings are clearly visible as a stand-alone element.
- Mars shows its red color and sometimes polar caps, but is small and difficult to get in focus.
- Venus shows apparent features like the moon, but has little detail.
- Mercury is difficult to see because of its low position and small size.
What is realistic in terms of magnification?
More magnification does not automatically mean a better image. The usable magnification of a telescope is about twice its aperture in millimeters. So a 130 mm telescope yields around 260x as its theoretical maximum, but the sky rarely allows this.
Practical advice:
- Keep in mind the exit pupil (aperture / magnification). For planets, 0.5 to 1 mm is optimal
- For planets, a magnification of 100x to 150x is ideal
- Use eyepieces from 10 mm to 6 mm, possibly with a good Barlow lens
The right telescope for planetary observation
Not every telescope is suitable for viewing planets. For sharp, high-contrast images, a few rules of thumb apply:
- Choose a long focal length: refractors of 900 mm or more, or Dobsonians of at least 6 inches, perform excellently for planetary observation.
- Note stability: a solid mount prevents vibrations and makes aiming easier. This is why for beginners we always recommend a Dobson telescope... but....
Dobson, refractor or smart scope?
What type of telescope works best for planets?
- Refractors with a long focal length (900 mm or more) are ideal for high magnifications and give sharp images.
- Dobsons are often larger, more affordable and ideal for visual observation. With a 6-inch (or larger) Dobson, you can already see impressive detail.
- Smart telescopes, such as the Seestar or DWARF 3, are optimized for astrophotography. They display the image on a screen. Useful for photographs, but less impressive for live visual viewing.
Want to view planets with kids? Then choose a Dobson telescope that lets you manually aim and focus. The wonder at seeing Saturn through a real eyepiece is irreplaceable.
Seeing, transparency and dark skies
Image quality depends not only on your telescope, but also on the atmosphere. Two terms are important here:
- Seeing - how stable is the sky? Turbulence causes shaky or blurry images. Stars twinkling violently indicate poor seeing.
- Transparency - how clear is the sky? Fog, moisture or light pollution can seriously reduce visibility.
Sometimes it is better to skip an observing night, but on clear, stable nights you suddenly see more than you ever expected.
Filters, eyepieces and the exit pupil
A good telescope is only really effective with the right eyepiece and accessories:
- Light blue filter (#82A) increases the contrast on Jupiter and Venus
- Moon Filter prevents overexposure of bright objects
- Some telescopes have a lens cap with small aperture - ideal to increase contrast
Also note the exit pupil the beam of light emitted by the eyepiece. You calculate this using the formula: aperture (in mm) ÷ magnification. In planetary observation, an exit pupil of 0.5 to 1 mm ideal for sharp, high-contrast images.
Get started right away? Let us help you
Have you become enthusiastic about observing planets yourself? Then check out our carefully selected telescopes especially suited for viewing planets such as Jupiter, Saturn and Mars.
➤ Discover the best telescopes for planetary observation here
Unsure which telescope is best for your situation? At the bottom right of our website you will find AstroBob, our virtual telescope expert. Ask your question whether it's magnification, filters or eyepiece selection and get instant, customized advice.
Soon we will also publish separate guides for each planet, with observation tips and explanations of what to expect through different telescopes. Don't want to miss a thing? Sign up for our newsletter.
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