Jupiter, named after the king of the Roman gods, is the largest planet in our solar system and the fifth planet from the Sun. Recognizable by its distinct bands of swirling clouds and its Great Red Spot, a massive storm that has been raging for centuries, Jupiter has long fascinated astronomers and laypeople alike. As a gas giant, it is primarily composed of hydrogen and helium, similar to the Sun, and its powerful magnetic field creates stunning auroras at its poles.
Jupiter is often called the king of the planets because it is the largest of the eight planets. Jupiter’s diameter is approximately eleven times that of the Earth. In fact, you could take the seven other planets and put them all inside Jupiter, and there would be room to spare. Jupiter is huge! And it is easily observed even with a small telescope.
We will learn a little about Jupiter, and then we will discuss observing Jupiter with your binoculars and with a telescope. We will consider what can be seen and what to look for as you observe. We will also discuss stargazing tools to enhance the experience and the challenges we face when observing Jupiter.
Jupiter is called a gas giant because it is composed mostly of hydrogen and helium. As far as we know, there is no solid surface beneath the cloud tops of Jupiter. So when we observe Jupiter with a telescope, we are looking at the gaseous outer layer of the planet. But Jupiter’s clouds present a very interesting show.
Why isn’t Jupiter always visible in the night sky?
All the planets orbit the Sun, however, their orbit periods differ. Earth’s orbit is defined as 1 year. Jupiter’s orbit takes 11.88 Earth years. Jupiter orbits the Sun much slower than Earth due to its significant distance from our star, about five times that of the distance between the Sun and the Earth. On average, it spends about a year traversing each constellation of the Zodiac, moving to the next one approximately every 12 Earth months. This pace makes Jupiter’s motion through the sky predictable, enabling astronomers to track its position easily.
Jupiter is best visible around the period of opposition, the next of which will be on November 3, 2023. During this time, Jupiter rises right around sunset and is visible nearly all night, as well as appearing at its biggest and brightest as seen from Earth. Jupiter will be visible for the next few months as it drops into the evening sky throughout early 2024, disappearing low at sunset in late April, in time for the superior conjunction on the other side of the Sun on May 18th. This cycle then repeats, with Jupiter emerging low in the pre-dawn sky in June and gradually getting higher and higher before another opposition on December 7, 2024, and the following superior conjunction on June 24, 2025.
Jupiter and the Earth travel in elliptical orbits, meaning they are not perfect circles. And since the Earth circles the Sun faster, the distance between Jupiter and the Earth is constantly changing. During periods where Jupiter is near its farthest from the sun (aphelion) around opposition, it is about 660 million kilometers (410 million miles) away, while during the best oppositions (around perihelion), it is only 590 million kilometers (366 million miles) away. So, there are better and worse years to view Jupiter.
How Do We Find Jupiter?
A simple internet search will find the dates when Jupiter will be visible in the evening sky. Or you can use a planetarium program, like Stellarium, that displays the sky and the movements of the planets and stars. The picture shown here is a screen capture from Stellarium.
The view shown is facing directly south from approximately 40 degrees north latitude. The red line that goes from left to right in an arc is called the ecliptic. It is an imaginary line that goes from East to West along which the Sun, Moon, and planets appear to travel.
The view shown is facing directly south from approximately 40 degrees north latitude. The red line that goes from left to right in an arc is called the ecliptic. It is an imaginary line that goes from east to west, along which the Sun, Moon, and planets appear to travel.
To locate the ecliptic, simply watch the path of the Sun as it goes from sunrise to sunset. If the Moon is visible at this time, it will travel along a similar path. The Moon is shown in the picture.
When Jupiter is in our night sky, it will follow a similar path. Just like the Moon, Jupiter will rise in the east, travel the ecliptic, and set in the west. So, when Jupiter is in the sky, it is easy to find.
Jupiter is very bright. If we look at the brightest objects in the sky, they are the Sun, Moon, Venus, and then Jupiter. So, when Jupiter is in the sky, it is brighter than any other star in the sky.
You might mistake Jupiter for a bright star, but when you notice it is on the ecliptic, you will also notice that it looks larger than a star. And if you look at Jupiter with binoculars, you can see that it is a disk, not a point of light.
Finding & Observing Jupiter with a Telescope in the Daytime
Under exceptional conditions, like Venus, it is possible to spot Jupiter in the daytime during periods when it is not particularly close to opposition or too near the Sun in the sky. It’s easiest to track the planet after sunrise if you’ve spotted it in the pre-dawn sky, but during evening apparitions, it’s possible to find the planet as a yellowish dot if you know exactly where to look. Binoculars or a finder scope will reveal it without much trouble, but exceptionally clear skies free of smoke, haze, smog, or dust are needed to spot the tawny orb with your unaided eye. You should, of course, avoid looking directly at the Sun with your eyes or any optical instrument and set up in the shade if you are making this attempt.
Daytime can be surprisingly good for observing Jupiter; the blue sky acts as a natural filter, enhancing contrast in the planet’s cloud bands, though the Galilean moons are often washed out through smaller telescopes. If Jupiter is high in the sky, you might be treated to some surprisingly stable seeing conditions ideal for sharp views of the planet too.
What is Interesting to See When Observing Jupiter through a telescope or binoculars?
First, have a look at Jupiter with binoculars or through your finder scope, if you have any. Even modest 7×35 binoculars and 6×30 finderscopes are enough to see the four bright Galilean moons of Jupiter – Io, Europa, Ganymede, and Callisto.
When using binoculars, a magnifying finder, or the low-power eyepiece of a telescope, Jupiter and its moons will look something like this picture. The moons move through their orbits pretty quickly. As a result, their positions will be different every night. Some nights, you may only see two or three moons, as the other moons may be behind Jupiter. They can form interesting combinations.
Io, being the closest to Jupiter, has the shortest orbital period, only 42 hours. If you were to observe Jupiter for a couple of hours, you might actually see Io move behind Jupiter or come out from behind Jupiter. And, on occasion, you can watch one of the moons travel across the face of Jupiter, and you might be able to see its shadow crossing as well.
Europa circles Jupiter every 85 hours. Ganymede orbits in about 7 days. Callisto is the farthest out and takes 17 days to circle Jupiter. Compare this to our moon, which takes about 27 days to circle the Earth at a similar distance to Io. Jupiter’s immense gravitational pull means that the moons are traveling at immense speeds to stay in orbit around the gas giant.
The timing of the Galilean moons, as they passed in and out of Jupiter’s shadow, played a critical role in early timekeeping and navigation. In the 17th century, the Danish astronomer Ole Rømer first used observations of the motions of the moons, particularly Io, to estimate the speed of light. Importantly, regular eclipses of Jupiter’s moons occur when the moons pass into the planet’s shadow, causing them to disappear from view momentarily
The regularity of the Galilean moons’ orbits and their eclipses by Jupiter were also used in establishing a method for determining longitude at sea. By comparing the observed times of these eclipses with tables listing predicted times based on the time at a known location (such as Greenwich, England), navigators could determine their longitude. This method, however, required very precise timing, a clear view of Jupiter, and considerable skill and experience. It was eventually superseded, but not until the development of sophisticated clocks in the late 1700s. Imagine if your life depended on these observations with a telescope likely weaker than a pair of 7x binoculars!
One of the most captivating phenomena involving Jupiter and its moons are the shadow transits. These occur when one of the Galilean moons passes in front of Jupiter, casting a small, dark shadow onto the planet’s cloud tops. Shadow transits can be observed with a 3” (76mm) or larger telescope. They offer a unique opportunity to witness the Solar System in motion from our vantage point in real time. Occasionally, observers on Earth are treated to the remarkable sight of double or even triple transits, when two or three of the Galilean moons and their shadows cross Jupiter at the same time. These events are relatively rare due to the specific alignment required between Earth, Jupiter, and the moons.
On a very good night, you may be able to see broad surface details – shading known as albedo features – on the Galilean moons. These do correspond to geological features but are usually too broad to match anything specific. Io features a yellowish equator with dark-orange poles, Europa is an off-white; Ganymede features several broad darker and lighter regions; and Callisto’s surface looks peppery. An 8” telescope can show you these features on a very steady night; a 12” or larger instrument reveals a few specific details on Ganymede and the broad brownish patches on Europa.
Jupiter has more than 90 additional moons, but most cannot be seen with typical hobby telescopes. However, if you have a large enough telescope, say 16” or larger, you may be able to see more than these four brightest moons. Observing the non-Galilean satellites of Jupiter is a challenging but rewarding task for experienced astronomers. Among Jupiter’s moons, Amalthea stands out due to its size. Despite being much smaller than the four Galilean moons (Io, Europa, Ganymede, and Callisto), Amalthea is significant as it is roughly equivalent in size to all of Jupiter’s non-Galilean moons combined. However, observing Amalthea is not an easy task due to its proximity to Jupiter and its faint magnitude of around 14,1. To catch a glimpse of this moon, you would need a telescope with an aperture of at least 20 inches, although a telescope of 36 inches or larger would be preferable. Amalthea orbits very close to Jupiter, completing an orbit in just 12 hours.
Himalia, an outer irregular satellite, is a notable object for amateur astronomers. Its visual apparent magnitude, varying between 14.6 and 15.6, allows it to be observed with a 10-12 inch telescope. It takes Himalia 250 days to complete an orbit around Jupiter. Due to this extended orbit, Himalia moves very slowly across the sky, at times appearing up to 1 degree from Jupiter.
As mentioned earlier, what we see of Jupiter is the top of the clouds. Jupiter’s atmosphere is a turbulent, colorful tapestry of clouds and storms, visible through even modest telescopes. The most prominent features are the dark belts and lighter zones that encircle the planet parallel to its equator. The belts are lower in the atmosphere where the air pressure is higher, and they are hotter, darker, and composed of denser clouds than the zones. The zones are areas of rising, cooler, cloud-free air. Magnifications as low as 20x will begin to reveal the main brick-red equatorial belts. They straddle a lighter region known as the equatorial zone, which sometimes contains a system of smaller, fainter belts. These belts and other zones shift over time, and their widths, colors, and intensities can change from year to year. Observing these dynamic atmospheric features provides a fascinating view of the weather on a planet very different from our own.
As mentioned earlier, what we see of Jupiter is the top of the clouds. However, Jupiter’s clouds tend to form into bands and these can be seen with our telescopes. Even at 60X in a 70 mm telescope, you can begin to see the two main cloud bands which are shown at the right in a darker tan shade.
Depending on the aperture of your telescope and the atmospheric conditions you may be able to magnify Jupiter enough to see shadings at the poles. Apply more magnification and you may start to see more regions of bands and even swirls within the bands called festoons.
The Great Red Spot
Jupiter’s atmosphere is also marked by storms, the most famous of which is the Great Red Spot, which has gradually shrunk and sometimes becomes more of a pink or orange color than red. Other, smaller storm systems, called white ovals, can be seen as well. Between the belts and zones, there are sometimes intricate, wavy structures called festoons. Jupiter rotates once every approximately 10 hours, so that is fast enough for you to watch the Great Red Spot move even during a 1-hour observing session.
The Great Red Spot on Jupiter, a storm that’s raged for at least 300 years, is one of the most distinctive features in our solar system. The first recorded observation that may refer to the Great Red Spot is from the 17th century, but the storm’s continuous observation began in the 19th century. The storm has been closely monitored ever since. It has dramatically decreased in size over the centuries; at its largest, it was three times the size of Earth, but now it is just over one Earth diameter across. Despite shrinking, the Great Red Spot remains a subject of intensive study due to its longevity and powerful winds, which reach speeds of up to 430 kilometers per hour.
If you do an internet search you can find programs and websites devoted to predicting when the Great Red Spot will be visible. The phone app, Jupiter Simulator, which I mentioned earlier, also tells you when the GRS will be visible.
Telescope Color Filters for Observing Jupiter
Most of the time, you will likely observe Jupiter without telescope filters. However, using colored filters that attach to the eyepiece can help bring up details that you might not be able to see otherwise. Color filters may not work well on telescopes with less than 100 mm of aperture, but go ahead and try them. A Baader Neodymium Moon & Skyglow filter is helpful for bringing out many Jovian details and eliminating residual glare and chromatic aberration; refractor owners may want to try the stronger Contrast Booster or Fringe Killer filters.
Colored filters are often numbered based on the Wratten numbering system. Wratten is a system also used for photographic filters. Light yellow, #8 and yellow, #12, can help enhance certain features in the cloud bands of Jupiter. Red and orange features will be emphasized. Deep yellow, #15 can sometimes bring up the festoons in the cloud bands. Don’t expect these filters to cause things to explode into view. They enhance subtle shadings and help bring up details, but they won’t radically change what you see.
The #80A filter is often called the Jupiter filter. This is a blue filter, and many say if you only have one color filter, this is the one to have. The #82A filter is also a blue filter and also works well for Jupiter. Of all of the color filters, this is likely the most handy to have; the blue brings out the cloud bands very well. You can also try observing Jupiter in the daytime to get this effect; the sky acts like a similar blue filter without as strong a tint.
What Size Telescope Do You Need?
While Jupiter is very large, compared to the other planets, it is still quite distant from us. You are looking at something that is 400 million miles away.
The larger the aperture of your telescope, the more light it gathers, the more detail you are likely to be able to see and the more magnification you will be able to apply to the image. An 80 mm telescope may be limited to 120X under most conditions. A 200 mm telescope may be able to apply over 250X and bring out more details.
Seeing and Transparency
Remember that you are viewing Jupiter through miles and miles of air that will distort the image and refract the light as it comes from Jupiter to your telescope. The condition of the atmosphere, or air, will vary from night to night, as will the quality of the image you get and the amount of magnification you can apply.
Air pollution, high humidity, smoke, and other things that scatter light will make things look less sharp. Turbulence in the air, the thing that causes stars to twinkle, will cause the image to drift in and out of focus. These disturbances become more evident as you go up in magnification.
So, if the image of Jupiter tonight doesn’t seem as good as it did a couple of days ago, it just may be the atmospheric conditions that are causing the difference. Making sure that you are in a good location for atmospheric stability (North American users, check Astrospheric) is a must, as is avoiding observing over pavement or rooftops if possible. Also, be sure that your telescope is accurately collimated (check our collimation guide for more info) and that it has fully cooled down. Light pollution doesn’t affect Jupiter or the Galilean moons, but it will wash out the faint irregular satellites.
Conjunctions and Occultations of Jupiter
Due to its position along the same plane as the rest of the planets in the Solar System (the ecliptic), Jupiter frequently appears in conjunction with other planets in the night sky. Occasionally, these conjunctions are close enough that both Jupiter and another planet can fit in the same telescopic field of view, offering a unique observational experience. The next of these will be on June 4, 2024, when it will be close to Mercury, very low in the dusk sky. A more favorable event (albeit early in the morning) will take place on August 14, 2024, when it will be as close as 18 arc minutes (a little less than the diameter of the full Moon in the sky) away from Mars, depending on where you witness the event from. The next planetary conjunction takes place a year later, on August 12, 2025, when Jupiter will pass about 1 degree from Venus low in the dawn sky.
Jupiter’s moons can also occult each other, or the moons of Saturn during very close conjunctions of the two gas giants.
Jupiter often participates in lunar occultations and conjunctions, where the planet either appears very close to our Moon or is blocked by it. These celestial events can provide a breathtaking spectacle, especially when the bright disc of the Moon occults the largest planet in our solar system. You can witness these events in broad daylight, provided that the Moon and Jupiter are not too close to the Sun in the sky, owing to Jupiter’s brightness. If you are not on the occultation path, you will witness a close conjunction between the two objects. The next set of these is in 2026 and 2027.
Approximately once every 399 days (its synodic period), Jupiter enters conjunction with the Sun between oppositions, making it unobservable due to its position on the far side of the Sun from Earth. During this time, Jupiter is hidden in the Sun’s glare and is at its furthest from us.
Jupiter is predominantly composed of hydrogen and helium, similar to the Sun or another star, hence its classification as a gas giant. These gases make up about 90% and 10% of Jupiter’s atmosphere, respectively. The planet also contains traces of other substances like methane, water, ammonia, and rock. Deeper within Jupiter, the intense pressure compresses the hydrogen gas into a liquid, creating what is known as “metallic hydrogen”. This exotic form of hydrogen, combined with Jupiter’s fast rotation, generates the planet’s powerful magnetic field.
Jupiter is the behemoth of our solar system. It’s so large that over 1,300 Earths could fit inside it. In terms of mass, Jupiter is even more impressive, weighing in at more than 300 times the mass of Earth. Jupiter’s gravity is so immense that the planets, asteroids, comets, etc. orbit not the Sun but a point slightly outside its surface where it shares a common center of balance (like a fulcrum on a seesaw) with a much smaller but still impressive Jupiter. With a diameter of about 143,000 kilometers, Jupiter is over 11 times wider than our home planet. The gas giant’s size and mass contribute to Jupiter’s influential role in shaping the orbits of many other objects in the solar system.
Jupiter’s strong gravitational field plays a critical role in the stability of our solar system. It’s believed to act as a kind of celestial shield, with its massive gravity deflecting comets and asteroids that might otherwise pose a threat to Earth. This concept was demonstrated in 1996 when the Shoemaker-Levy 9 comet collided with Jupiter. While Jupiter’s gravity can and does send some objects on a collision course with Earth, on balance, it flings more objects out of the Solar System or simply absorbs them than it sends inward.
In some ways, Jupiter can be likened to a failed star or a brown dwarf. Brown dwarfs are objects that are too large to be classified as planets but are not large enough to sustain hydrogen fusion, the process that powers stars. Like a brown dwarf, Jupiter is predominantly composed of hydrogen and helium. It also radiates more heat than it receives from the Sun, due to the slow gravitational contraction of the planet, a characteristic shared with brown dwarfs. However, Jupiter is far less massive than even the smallest brown dwarfs (which are a dozen times the mass of the king of the planets), so it could never have achieved the internal pressures and temperatures necessary for deuterium or lithium fusion to occur.
Unlike Earth, which has an axial tilt of 23.5 degrees and experiences significant seasonal changes, Jupiter’s axial tilt is just 3.13 degrees. This negligible tilt means that Jupiter doesn’t have the same kind of seasons that Earth does. It’s almost as if Jupiter has a perpetual equinox with only slight variations in sunlight and temperature between its polar and equatorial regions. This minimal tilt is also why the gas giant’s cloud bands appear nearly straight.