Ever wondered how to view and photograph the planets? Viewing the planets in our solar system is on every observer's hit list during a session under the night sky. Popular with beginners and seasoned astronomers alike, these worlds can often be spotted with the unaided eye, while binoculars and telescopes allow skywatchers to see further details, from the tempestuous storms of Jupiter to the majestic rings of Saturn.
If you're looking to capture even more intricate features that naked eye observing doesn't allow, then there are plenty of pieces of equipment at your disposal to help: imagers — particularly CMOS, CCDs, DSLRs, smartphones and some webcams — along with colored filters, eyepieces and photo-editing software will create truly breathtaking results, especially if a planet is at its best place for viewing (also known as being in opposition), or at a dazzling magnitude.
What type of telescope is best for observing and photographing the planets?
Choosing the best telescope for observing and photographing the planets depends on whether you plan just to visually observe them or if you want to photograph them too. Some planets — particularly Venus, Mars, Jupiter and Saturn — can reach spectacular magnifications, presenting bright disks brimming with a wealth of detail ready to be observed with telescopes with apertures of at least three inches (76mm).
Further afield, Uranus and Neptune can remain faint and appear small in the sky even at their best time for observation. Meanwhile, the inner planet Mercury might be close to the sun, but its small size makes it elusive in the sun's glare. Patience, equipment, and observing conditions (for example, a suitably dark sky) are required, as each planet presents its own observing challenges.
It should be highlighted that five planets in the solar system can be seen without equipment. Mercury, Venus, Mars, Jupiter and Saturn can all reach impressive brightness — but of course, you can't see any details on them without an optical aid, other than say, the red hue of Mars and the yellow appearance of Saturn. However, conjunctions between the Moon and planets are a beautiful sight for skywatchers looking to observe casually.
A good set of binoculars in the range 7x50 to 10x50 will show you the four main moons of Jupiter — Io, Europa, Ganymede and Callisto — the largest Moon of Saturn (Titan), and the distant planets Uranus and Neptune, as bright points of light even under minimum light pollution. If you're lucky, the atmosphere is steady and you're observing from a location devoid of light pollution, it is possible to spot the rings of Saturn and the atmospheric bands of Jupiter with magnifications of 10x50 or above.
What size telescope is best?
To really start to see details on the planets, you'll need a telescope. At this stage, what matters is the aperture, not magnification. A cheap plastic 40mm/1.5-inch aperture telescope with 500x magnification will not show you anything on the planets, because its small aperture is not big enough to collect enough light to resolve the details that you want to magnify.
The minimum aperture telescope that you'll want to comfortably observe the planets is 4 inches (102mm). Examples include (but are not limited to) starsense_explorer_lt_114.html" style="text-decoration: underline; box-sizing: border-box;">Celestron's AstroMaster 114EQ, Orion's StarBlast 4.5-inch reflector or Explore Scientific's 114mm FirstLight. Check out our guides on the Best telescopes and the Best telescopes for seeing planets for an instrument that's within your budget and level of expertise.
It doesn't matter at this stage what type of telescope it is, whether it's a reflector, refractor or Schmidt-Cassegrain. Any well-made 4-inch telescope from a reputable astronomical dealer will show you the phases of Mercury and Venus, dark and light surface features on Mars, the belts in Jupiter's atmosphere and its Great Red Spot, as well as Saturn's famous rings.
What eyepieces and magnification do you need?
You should aim for a magnification of about 25x per inch of aperture. For example, if you want to observe Jupiter's belts and bands with a 4-inch telescope, then you need a magnification of about 100x — too much and your views will become blurry.
To calculate the magnification that an eyepiece provides, you need to divide your telescope's focal length (in mm) by your eyepiece's focal length. Additionally, you don't need to break the bank for a good planetary eyepiece, Plössls with a short focal length (and often supplied with telescopes) will suffice as a starting point. Take a look at our Best eyepieces for telescopes feature to ensure that you're weighing up your options.
In some cases, filters will be an advantage. This is particularly true for Mars, which boasts a multitude of features given its mountainous and carved terrain. Filters come in different colors and screw — or thread — simply into your eyepiece. They are used to enhance certain details. For example, orange or red filters will enhance the appearance of dark features on Mars' surface such as the V-shaped Syrtis Major. A blue filter, meanwhile, can highlight clouds on Mars, and in the atmospheres of Jupiter and Saturn. An ultraviolet filter, such as the Alpine Astronomical Baader U-Venus filter, can show subtle details in the atmosphere of Venus. Filters can often be bought in sets, such as Alpine Astronomical's Baader Colored Bandpass Eyepiece Filter set, meaning you can get all the filters you need in one go and for a reasonable price.
Choosing a larger telescope
The larger the aperture of your telescope, the more detail on a planet you will see. If you're willing to spend a substantial budget on a larger telescope for viewing the planets, then you will want to make sure it's optimized for doing just that.
Following the rules about magnification, then the larger your aperture — say eight or ten inches — the more light your telescope can gather. With more light to play with, the better it can handle increased magnification. An 8-inch (~200mm) telescope can handle 200x magnification quite easily, resolving finer details on, for example, the surface of Mars or in the rings of Saturn. That said, just how well your telescope accepts magnification doesn't just depend on its aperture but also its focal ratio. This is calculated by dividing the telescope's focal length (the distance it takes for the light to come to focus on the telescope's tube), by the aperture.
You may want to consider whether your telescope is 'fast' or 'slow.' These terms are hangovers from the old days of photography and refer to your telescope's focal ratio. A focal ratio below f/5 or f/6 is considered 'fast,' and above is slower. Faster telescopes provide a wider field, and as a planetary observer, this is something you don't usually want. This is because the planets — against the sky— are actually quite small — Jupiter, for example, ranges between about 30 and 46 arc-seconds in size.
In contrast, star clusters, nebulae and galaxies often span arc minutes (there are 60 arc minutes in a degree and 3,600 arc seconds in a degree). Therefore, if you observe or image a planet in a wide field, the planet will appear small, and the telescope will not take magnification well. For this reason, planetary observers often choose slow telescopes. Popular instruments for planetary observers, particularly those doing imaging, are Schmidt-Cassegrain telescopes, or SCTs for short. The classic example is Celestron's line of SCTs, particularly the 'C8' model, which has an aperture of 8 inches, a focal length of 80 inches, and a focal ratio of f/10. The latest version of the C8 is the Celestron Advanced VX 8-inch.
Photographing the planets
There are several ways to capture the planets in digital form, ranging from an everyday smartphone to dedicated CMOS and CCD cameras. You'll need an imager if you're looking to pick out the finer, more intricate details on planetary surfaces and atmospheres.
When imaging, the camera connects to the telescope where the eyepiece slots in. Dedicated astronomical cameras have threads that screw onto the telescope, but DSLR cameras require adaptors, such as the Novagrade Digiscoping Adaptor for Canon DSLR cameras, or Sky-Watcher's M48 threaded adaptor for Canon cameras. There are also simple devices that can screw onto your telescope that can hold your smartphone, such as the Celestron NexYZ Smartphone Adaptor — allowing you to image with ease.
There is a huge choice of cameras on the market. Astronomical CMOS and CCD are optimized for imaging the heavens. They can only be used at the eyepiece and are controlled by software — they are not normal cameras in that sense. Imagers working to a budget might like to try Celestron's NexImage 5 Solar System Imager with its 5MP CCD sensor. For the more well-heeled astronomer, Starlight Xpress' Trius range of CCDs offers high-quality instrumentation from a company with decades' worth of experience designing astronomical cameras.
If you prefer a more versatile camera, then you might choose a DSLR, which can also be used for non-astronomical terrestrial photography, from holiday snaps to photographing wildlife. The Canon Rebel T7 is an affordable entry point into DSLR imaging. Try our best cameras for astrophotography, if you're currently in the market for a camera.
The key difference between DSLR astrophotography and (most) CCD imaging is that DSLRs are essentially one-shot imaging, whereas many CCDs are monochrome, meaning that if you want to see the color on say, Mars or Jupiter, you'll also need to invest in a set of LRGB filters (luminance, red, green and blue), and then combine the exposures taken through different filters using stacking software such as RegiStax. You will then need to process with an art package such as Adobe Photoshop. The best photo editing software for you will depend on your budget, the type of images you're looking to create and your existing setup.
Earth's own atmosphere can provide a challenge for astrophotographers. Atmospheric turbulence and clarity, referred to as 'seeing' conditions, can cause the quality of your view to fluctuate. Astronomers can get around this by taking lots of very short sub-exposures, controlled using software via a laptop or tablet. These sub-exposures are then stacked together, with exposures of 'bad seeing' being discarded, leaving only the best to be combined.
It's always best to plan your observations ahead of time — there's nothing worse than carrying all your heavy telescopic equipment outside, setting up your laptop, only to find the clouds rolling in and that you've wasted your time. Other times, you might already know the weather is bad, but be wanting to sneak outside if the sky clears for a few hours.
Watching weather forecasts obviously helps, but the keen astronomer needs up-to-the-minute weather reports. In this case, a weather station is essential. Not only do they tell you how long it will be cloudy, but they can also provide measures of ambient temperature and relative humidity, important when considering the quality of the seeing conditions (warmer air means more thermal currents and turbulence) and whether your telescope is likely to dew up, in which case a dew heater, such as the Vixen Optics Lens Heater, will be necessary.
The other problem is that planets rotate, so if you image for too long then the rotation of the planet you are imaging can cause the image to blur. This can be mitigated again by taking short sub-exposures and also by applying de-rotation software such as WinJUPOS.
Earth also rotates on its axis, which means that the sky appears to rotate overhead. Therefore, an essential piece of kit for imaging is a motorized equatorial mount that is able to track your target planet in the sky as the heavens rotate above you. Your mount will need to cater for the weight of your telescope, camera, filters and any other paraphernalia you have strung up on it, so make sure you get a heavy-duty one. The Sky-Watcher EQ5 or EQ6 can carry payloads of 30 lbs and 44 lbs respectively, and Celestron's CGEM II mount can carry 40 lbs.
Observing and photographing planets is tremendously rewarding. Unlike the (mostly) unchanging stars, planets can change — they rotate, they change their angle towards us, and they experience storms in their atmospheres. There's always something to look out for, and armed with any of the aforementioned kit, you'll be well placed to see the planets at their very best.
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Gemma currently works for the European Space Agency on content, communications and outreach, and was formerly the content director of Space.com, Live Science, science and space magazines How It Works and All About Space, history magazines All About History and History of War as well as Science, Technology, Engineering, Arts and Mathematics (STEAM) kids education brand Future Genius. She is the author of several books including "Quantum Physics in Minutes", "Haynes Owners’ Workshop Manual to the Large Hadron Collider" and "Haynes Owners’ Workshop Manual to the Milky Way". She holds a degree in physical sciences, a Master’s in astrophysics and a PhD in computational astrophysics. She was elected as a fellow of the Royal Astronomical Society in 2011. Previously, she worked for Nature's journal, Scientific Reports, and created scientific industry reports for the Institute of Physics and the British Antarctic Survey. She has covered stories and features for publications such as Physics World, Astronomy Now and Astrobiology Magazine.
The only way to get really great planetary images is shooting hires video with a scope in the order of > 3000mm focal length; otherwise, you're probably going to be disappointed.Reply