If you own a telescope you may be wondering what magnification works best for observing Jupiter and what features are you likely to see? Moons? Rings? The Great Red Spot? You know how great Jupiter looks through the eyes of NASA, but what about Jupiter through telescope types available to you…
From music and the arts to its place in the solar system, as the biggest solar system planet, Jupiter has always conveyed magnitude and majesty.
The standout Jupiter features
Jupiter has moons, rings, and clouds (as covered below), but the most distinctive feature of the planetary king of our solar system is the Great Red Spot.
Visible since the early 19th century, Jupiter’s Great Red Spot as seen from Earth is really a massive storm (bigger than Earth itself!) that rotates clockwise.
Such storms on Jupiter rage for hours, weeks, or even centuries and can generate wind speeds of up to 100 miles per second.
The Jupiter surface
Jupiter is a gas planet and so has no true surface. What you see as the ‘surface’ of Jupiter through your telescope are swirling bands of gas and liquid. There’s no solid surface like our Earth or Mars.
Jupiter through telescope: what are you likely to see?
Jupiter has an apparent diameter of 45 arcseconds. When viewing Jupiter through telescope types, particularly ones best suited for viewing planets, you should see several cloud bands made up of zones (lighter bands) and belts (darker bands) running parallel to the equator from north to south.
The detail you see will depend on your telescope’s capacity but also on the observational conditions at the time.
Though Jupiter is not the closest planet to Earth, it is the king of planets with respect to size and so you’ll get to observe more details of Jupiter through telescope eyepieces than with your naked eye.
Jupiter has an apparent magnitude or brightness as seen from Earth on average of –2.20. It is brighter than the brightest star in the night sky, Sirius. So when it’s comes to finding planets, it is easy to spot.
Can you see the moons of Jupiter? I cover more of what you’re likely to see below. But first, it helps to know what you’re going to be looking at…
Just how big is Jupiter?
Jupiter has a radius of roughly 43,440.7 miles (69,911 km). To put that into context, that’s 318 times bigger than Earth and 2.5 times bigger than all the rest of the planets in the solar system combined. A quote from NASA: “If Earth were the size of a grape, Jupiter would be the size of a basketball” explains it best.
There’s a catch to this enormity, however – if Jupiter were to get bigger it would actually shrink as gravitational forces of added mass and density would start to pull inward.
While it’s massive, Jupiter is still the fastest spinning planet in the solar system. Jupiter is a giant gas planet, primarily consisting of hydrogen (H2) and helium (He).
The Greeks called this planet Zeus, but the Romans renamed it after their God, Jupiter. The naming, in both cases, reflects the king deity of their pantheons and this understandably corresponds to the king-size of this planet.
How many moons does Jupiter have
Jupiter moons number at least 79, as at 2019. Fifty-three of these are named. The four largest (Ganymede, Io, Callisto, and Europa) were discovered as far back as 1610 by Galileo Galilei, hence, the term “Galilean moons”. These were the first orbital objects, apart from a planet, to be discovered.
The four Galilean moons of Jupiter are some of the largest objects in the solar system, with Ganymede outsizing Mercury and so you are likely to see these moons of Jupiter through telescope types available for home use.
Appropriately, all the Galilean moons of Jupiter have been named from figures that the deities of Jupiter and Zeus “interact with”. So, if you are into viewing these moons… check out my article on what you can expect to see and how to identify the moons of Jupiter.
Seeing the four Galilean moons of Jupiter through telescope types setup for planet viewing is possible under the right conditions. More on that below.
Does Jupiter have clouds?
The stripes and swirls that you see in images are known as the clouds of Jupiter, but these are not the clouds we know of on Earth. NASA tells us these are actually “cold, windy clouds of ammonia and water floating in an atmosphere of hydrogen and helium”.
Does Jupiter have rings? Jupiter rings facts
While we typically associate rings with Saturn, Jupiter has them as well. Though, the rings of Jupiter are much fainter to observe than the rings of Saturn. Dust comprises most of Jupiter’s rings, involving four components: an inner halo, a bright but thin main ring, and two gossamer outer rings. This compares to Saturn’s rings, which comprise ice. Though, like Saturn’s, the rings of Jupiter are slowly dissipating.
Jupiter’s rings and other features are clearly evident in images from spacecraft observations of Jupiter. The Juno Orbiter, the latest spacecraft exploring Jupiter, is among other satellites and spacecraft imaging the giant, including the Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysses, Cassini, and New Horizons.
How to see Jupiter yourself
In terms of viewing Jupiter for yourself, the planet’s size and brightness make that far easier to do than many other celestial objects in the night sky.
First, you’ll want to make sure that Jupiter is actually “in the sky” the night you plan to observe. Of course, it’s “there,” but as celestial bodies move and lighting and darkness conditions change throughout the year, it may be visible some nights more so than others.
How to see the king of planets in the night sky
Check a star chart or use a star-charting app such as Stellarium to make sure you stand a fair chance of spotting Jupiter through a cheap telescope, binoculars, or even with the naked eye. I find timeanddate.com has a useful page for checking the night sky for the planets that are visible on a given night and the time expected at your particular location.
You’ll also want to make sure that you have configured the settings of your star map app for the right hemisphere. What celestial bodies appear at what times in your area will depend on this.
So, make sure you choose your location on Stellarium or check whether the star chart you are using is for the Northern or Southern Hemisphere.
Jupiter is the third brightest celestial feature most nights after the Moon and Venus (I wrote about this in What Does Venus Look Like Through a Telescope), so if you’re looking at something fairly bright, there’s a reasonable chance you’re on the right track.
That said, you’ll also need the conditions to be reasonably dark and clear. Trying to find Jupiter in a city full of light pollution is difficult.
If you’re lucky enough to have good viewing conditions, first, locate Jupiter in the night sky with your unaided eyes with the help of a star chart. Next, looking through the telescope, start with low magnification (larger eyepiece focal length) to focus in on the planet. Once you’ve got your telescope lined up, scale-up in magnification (smaller eyepiece focal length).
By the way, if you need to wear glasses you’re best using eyepieces that cater for the depth you need to comfortably look through the eyepiece. I cover this in my article on using telescopes with glasses.
To see the bands of Jupiter, you may only need magnification of 100x. For distinguishing the Galilean moons of Jupiter through telescope eyepieces, choose ones that give you say 120x or 150x magnification.
Working out eyepiece sizes:
Eyepiece focal length = telescope focal length ÷ magnification
So, for example, a 10 mm eyepiece on a scope with a 750 focal length will give you 75x magnification only. To get the 120x to 150x, you’ll need eyepieces in the 5 or 6 mm range. Alternately, using a 2x Barlow lens with the 10 mm eyepiece would give you 150x magnification.
The chosen magnifications work as long as they are within your telescope’s maximum useful magnification, which is typically listed in its specifications. The telescope’s aperture size will determine this. As a guide, it is 50 times the aperture in inches (or 2x the aperture in millimeters).
I cover how to work out magnifications and eyepiece sizes for planet viewing in more depth in my article on the best eyepieces to use.
Rings of Jupiter
Even if you crank it up to 150x or even higher, you’ll struggle to spot the Jupiter rings. These are much fainter than the rings of Saturn and they were only discovered in 1979 by NASA’s Voyager 1 spacecraft.
Best time to see Jupiter
Your best chance of seeing majestic views of Jupiter is when it is “in opposition.” This essentially means that Jupiter, the Earth, and the sun are aligned. This happens roughly every 13 months. The closer you are to this point, the easier it is to see Jupiter, as it is when it is closer to and in alignment with the Earth as opposed to elsewhere in its orbit.
As of this article, the next three Jupiter oppositions will occur on 14 July 2020, August of 2021, and September of 2022. On the 14 July 2020, it is expected to be shining at magnitude –2.8 and spanning 47.6 arcseconds.
Jupiter coinciding with Saturn in the night sky is a rare sight. You’ll see this around the solstice night sky of 21 December 2020. Look for this conjunction low in the west at dusk.
Colloquially called, the Christmas Star, it’s spectacular and rare to view Jupiter and Saturn together like this from Earth, an event that has not been seen for hundreds of years.
You’ll see Jupiter with Saturn in the same field of view. Jupiter will be the brightest of the two, and Saturn will be in a tilted position beside it. With the right magnification, you should see the major moons of Jupiter.
What about seeing Jupiter’s most notable feature, the Great Red Spot?
That will be tricky, even if you crank up the magnification on your home telescope.
Jupiter’s brightness and size are one thing to see, but for something that specific, you often need a slightly more refined telescope, though there’s nothing wrong with giving it a try and seeing if you can get lucky.
What makes Jupiter majestic?
Jupiter is possibly one of those few celestial bodies claiming a majestically exalted place not only in the cosmos but also in our hearts. At least…if you listen to Gustav Holst’s orchestral suite “The Planets” (and really, what better music to stargaze by?), you’ll find the Jupiter section to be among the most triumphant and jubilant.
Small wonder Holst named the Jupiter section “The Bringer of Jollity,” or why the United Kingdom adapted its music in 1921 for the post-WWI patriotic hymn “I Vow to Thee, My Country.”
As the biggest and most massive planet in the solar system (and we’ll soon get to how massive this gas giant really is), Jupiter has been visible since antiquity.
While it may be the “Bringer of Jollity,” things are far from peaceful within the atmosphere of this gas giant.
With all the above mind, we can see that Jupiter is special and worth trying to get a good view through your home telescope.
Just as his namesake looms large in Greco-Roman mythology, so too does Jupiter loom large in our solar system and, indeed, our imaginations. Since human beings have turned their eyes skyward, it has always been one of the most recognizable features in the night sky. If you are interested in astronomy, taking your telescope and trying to find “The Bringer of Jollity” can certainly bring joy and a sense of awe.
NASA: Jupiter moons | USGS: Planetary Names | NASA: In–depth about Jupiter | Springer: Jupiter and How to Observe It | Dateandtime.com: Night Sky Map