The dark-robed figure depicted in the inset on the left (a portion of a fresco by a 19th Century artist, Gioseppi Beatini) is Galileo Galilei, a 16th Century polymath and considered to be the first physicist, instructing the Doge of Venice on the use of one of Galileo’s telescopes. To the right of the fresco is a modern telescopic view of Jupiter surrounded by three of the four largest satellite.
You may read in some sources that Galileo invented the telescope, but that was a break-through achieved by glass lens makers in the Netherlands. Galileo heard about this Dutch “Spy-glass” and soon built a slightly better version for his own use. Galileo turned his new telescope to the skies and modern astronomy was born! His first target was the moon (what he saw is described in the introduction on the page devoted to observig the Moon) and then turned it to Jupiter, one of the brightest of the five “stars” that the ancient Greek astronomers called “planets” (wanderers we know as Mercury, Venus, Mars, Jupiter, and Saturn). Ancient visual astronomers knew the that planets behaved differently compared to all the other known stars. Normal stars appeared to maintain the same position relative to all other stars. These patterns of stars moved across the sky with the seasons, but the relative position of all the normal stars stayed constant. Planets looked like stars, but they appeared to change their positions relative to the fixed stars. Astronomers throughout the ancient world knew that this must be significant, but they tended to come up with magical explanations for their odd behaviour.
In 160alileo turned his telescope on the moon, making notes and sketches of what he saw. He was astonished by his opservations, which you can find in the preface of the Moon/Lunar page! His celestial target was the planet Jupiter, shining brightly in the Italian night sky. What he saw looked very much like this:
Jupiter imaged with modern binoculars.
Galileo had already noted that his telescope would make stars brighter, but but that they were still just points of light. Jupiter was different in that the telescope rendered it as a small disc, flanked on either side by four star-like points of light arranged in essentially a straight line! Through the course of the evenening and in the nights to come, this little star-like objects would shift their positions relative to Jupiter, but they were always positioned in a line! Sometimes only two or three of the objects were visible (see the modern telescopic image of Jupiter in the header of the Jupiter page and, if you look carefully, you will see three of the four little spots of light that puzzled Galileo, but not for long. He reasoned that if Jupiter were a sphere, the objects could be revolving around the planet on fixed courses at varying distances. If he was viewing the planet from the side, the objects would appear to be in line, but their apparent distance would vary. His model would also account for their varying number, as occasionally one or more of the objects would pass behind or in front of the planet, seeming to disappear. Galileo had discovered the four largest satellite/moons of Jupiter, which are know today as the Galilean satellites in his honor. You won’t see many images of the four moons in question on this page. In almost all cases, I attempt to get the best possible images of the planet itself, although some of the moons get into these close-up images when they happen to be close to Jupiter of they or their shadows can be seen as the happen to cross the planetary disc. Yout don;t need a powerful telescope to see the Galillean moons – a good pair of binoculars will do the job. Just be sure you can hold t\your binoculars stead as shaking hands will make them harder to see!
With Jupiter we are really beginning to move into the outer solar system. Jupiter is a long way from the Earth, even at opposition (~390 million miles/626 million km), but it is so big (11 times the diameter of the Earth) that is the largest planet you will observe or image with a telescope. Small planets such as Mars are best viewed within a few weeks of their opposition, but Jupiter is worth a look as long as you can see it in the night or morning sky.
Jupiter has 53 confirmed satellites/moons (as many as 16 more are awaiting confirmation), but only the largest four, first observed by Galileo over 400 years ago, are routinely visible in amateur telescopes.
When you look at Jupiter, you are not seeing the solid surface of the planet. Instead, you are looking at the the very high tops of clouds that essentially block any view of what lies beneath. However, those clouds are highly varied and dynamic and well-worth observing. What you are seeing is a grand case of weather, a global heat machine unrivaled in the solar system. The modest heat from the sun combines with the very significant internal heat of the planet itself to keep the atmosphere continuous churning, while the very fast rotational speed (a day on Jupiter is only about ten hours long) adds to the mix of forces acting on the atmosphere. The broad latitudinal bands of clouds owe their color differences to the mix of gasses and although the bands are usually somewhat stable, they can change with time. The largest single storm on the planet, the Great Red Spot, is a hurricane-like weather system larger than the size of the Earth; which has persisted (at varying intensity) for several centuries. Click on Jupiter on the [NASA Solar System Exploration] page for much more information on this giant of the Solar System.
Now for some information on the collection of Jupiter images you will find here. A large amount of information is recorded for each of my images, but in order to illustrate a larger number of images, information here is limited to the date and time the image was captured. If you have any question on specific examples or you could use more technical data, just email me at taggart@msu.edu with the planet and the image date/time and I will provide you with all the available information.
2018 Jupiter Apparition
Note: the proper date for the final image is 2018-07-09.
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2019 Jupiter Apparition
Recovery from surgery shut me out of the observatory for several months. As a result I missed the very earliest stages of this year’s apparition. The single biggest problem with this year is the extremely low elevation of the planet as viewed from mid-northern latitudes. This year Jupiter was at approximately the same elevation that Mars was last year, with the potential for significant atmospheric distortion.
When I finally got into the observatory on 24 April, I was pleased to see that the solar charging system had kept the battery fully operational and that all other aspects of the Observatory appear to have gotten through the winter with no problems. Conditions were far from optimum, as you will see from the interval between images, weather was a significant factor this year.
The two monochrome images marked with an asterisk (*) were obtained using a Near IR filter (the same one that saved last year’s Mars apparition), which was very effective in minimizing the effects of poor “seeing” at the very low (20-23 degrees) elevation of Jupiter this year.
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2020 Jupiter Apparition
This year it theoretically became possible to image Jupiter in mid-May, but the usual mid-Michigan weather delays pushed the first opportunities until later in the month. If the image is in color and no mode is specified, the image is derived from RAW data with de-bayering (color synthesis) done relatively late in processing via a process called Drizzling. This is new for this year and will used in almost all cases of color imaging given the flexibility of the approach. Color images with an RGB24 designation are recorded with 8-bits of Red, Green, and Blue primary color data. This is the way I used to do all my color images, but not this year. Monochrome images with the NIR designation are taken through a near-infra-red filter. NIR images are excellent for penetrating dust, as was the case with the Martian dust storm of 2018, and is much less impacted by atmospheric turbulence, usually resulting in much sharper images then when visible light (RAW/RGB24) is used. Images will be added in blocks through this year’s apparition. A great deal of data are collected with each image, so if you would like more information on specific images, drop me an email.
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2021 Jupiter Apparition
The weather this summer started out hot with serious storm activity. For July, at least, there will probably be serious gaps between sessions.
The early morning hours of 04 August provided exceptionally-good “seeing”, which justified both Near-IR (NIR) and conventional color imaging. Prime-focus imaging (f/20) with the observatory’s OMC200 telescope normally yields images of Jupiter equivalent in size and detail the majority of images on this page. When seeing is well-above average, much greater image scales can be achieved.
It is now early October and the end of the apparition is in sight. As is my custom, I have been logging almost all images, but, at the end of each apparition I reduce the current crop of images to the best examples. Most of the better images are f/20, but there were a few opportunities for larger (f/30) images, seen toward the end of this new collection.
The last image of an apparition is bittersweet, especially this year. Climate change has significantly reduced the number of days where quality imaging is possible. There were some fine images, but not all that many. Bad weather (rain and later snow) basically shut down the observatory from mid-October until late in December. A few December days had clear skies, but by then Jupiter was getting lost in the trees to the SW. So, we bid Jupiter goodby as gets closer and closer to passing behind the sun. Opposition next year will be on 26 Sept. where it will reach an elevation of 52 degrees (the best in quite a few years now), reaching an apparent diameter of just shy of 50 arc-sec. With any luck, that should mean some fine observing options through the Summer and into the Fall months. As they say, “Hope springs eternal…..”
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2022 Jupiter Apparition
The weather was not cooperative in the late Summer and early Fall, with a great deal of rain and even more cloudy skies.
2023 Jupiter Apparition
For the past five years I have been using my 8-inch OMC200 Maksutov to capture the images posted to this website. It is a magnificent instrument, but it is heavy and unwieldy to handle when it comes to routine maintenance. I am lucky to be 82 years of age and still able to take an active role in life, but handing this marvel of a telescope is becoming difficult and I certainly do not want to damage it. So, the Fall I took the tOMC200 off the mount and replaced it with my beloved SV115 APO refractor. I will probably put the OMC200 up for sale as it is an instrument that should be used rather than simply storing it away.
The SV115 has a smaller aperture (115 mm) compared to the OMC200 (200 mm) and a much shorter focal length (800 compared to 4,000 mm), so capturing images as large and detailed as those from the OMC seems next to impossible, but I have some tricks to apply to the problem and I think I will be producing comparable images. Time will tell, but so far the weather has been abominable so there may be fewer images from the Fall into the early winter.
My calculations for stretching the focal length (and hence the image size, with my refractor APO instrument were dead on and the first image on October 4th appear at essentially the same scale and quality as the previous OMC200 contributions. Nineteen days of rain would pass until the next imaging session on October 23rd:
