NASA’s Juno spacecraft is right in the middle of its mission to Jupiter – and it’s feeding us back some spectacular images.

Back on October 29, 2018, NASA’s Juno spacecraft was somewhere between 11,400 and 31,700 miles above the skies of Jupiter. And on that date, the probe was on a close fly-by of the planet for the 16th time since its launch. But this particular trip would arguably be more notable than the ones that had gone before. During the jaunt, you see, Juno managed to snap photos that appear to present something rather strange indeed.

For its part, Jupiter is the largest planet to have been found in our Solar System thus far – two and a half times bigger than every other of its kind combined. And the celestial body is also designated as an outer planet, meaning it’s one of the four furthest away from the Sun.

The four inner planets in our Solar System are Earth, Mars, Venus and Mercury; the four outer ones, meanwhile, are Jupiter, Uranus, Neptune and Saturn. And of the latter quartet, Uranus and Neptune are known as ice giants, while Saturn and Jupiter have been dubbed gas giants.

Jupiter is mainly made up of hydrogen, you see, although around 25 percent of its mass consists of helium. And the further reaches of the planet’s atmosphere are split into a number of bands at differing latitudes, with this combination leading in turn to stormy conditions. In fact, one region on Jupiter hosts a single storm that is thought to have raged for hundreds of years.

The Great Red Spot is the region in question, with the consistent high pressure there resulting in what is known as an anticyclonic storm. And activity in that area has been recorded without disruption since 1830 – although the phenomenon is actually thought to have been witnessed since 1665.

Interestingly, too, Jupiter actually rotates more quickly on its axis than any other major planet in the Solar System, with a full revolution taking just under ten hours. In fact, the sheer speed of this process means that the planet bulges in shape at its equator. Nevertheless, Jupiter is not that fast in its orbit around the Sun; by contrast, just one of these sidereal periods lasts for more than 11 Earth years.

What’s more, Jupiter is said to be one of the most luminous objects seen from Earth – behind the Sun, the Moon and Venus, although Mars occasionally shows itself more clearly, too. But in any case, thanks to its ability to be witnessed without the need for scientific instruments, Jupiter has been spotted by mankind for millennia.

In the case of the ancient Babylonians, for instance, Jupiter was a representation of the god Marduk. It was the Romans, though, who actually christened the planet after the deity of thunder and the sky. And to members of the civilization, Jupiter was believed to be the king of the gods.

Image: NASA/Jet Propulsion Lab-Caltech/SETI Institute

Still, although Jupiter was a source of interest for several ancient societies, the ability to identify specific features of the planet only came with the advent of the telescope. And bearing that in mind, the first few of Jupiter’s many moons weren’t spotted until 1610.

In that year, you see, Galileo Galilei supposedly first observed moons beyond the one orbiting Earth. While peering through a telescope, the Italian noted what are now appropriately referred to as the Galilean Moons – although these were also named by the astronomer’s contemporary Simon Marius as Ganymede, Io, Callisto and Europa.

And over the subsequent centuries, many more discoveries have been made about Jupiter’s features. So far, for instance, there have been 79 moons recorded in orbit around the planet. The most sizeable of these celestial bodies is Ganymede, which is actually larger than Mercury itself.

Yet until the early 1970s, investigations of Jupiter had generally taken place from afar through the use of telescopes. Then, in 1973, the Pioneer 10 probe became the first ever craft to actually travel close to the planet. And Pioneer 11 soon followed, flying by Jupiter the very next year.

Furthermore, a number of other probes have since been sent to Jupiter in order to snap photos and make observations. Voyager 1 and Voyager 2 both flew by the planet in 1979, for instance, as a means of investigating some of the celestial body’s moons, while Ulysses analyzed Jupiter’s magnetosphere in 1992 and 2000.

However, it wasn’t until 1995 that a spacecraft actually entered into Jupiter’s orbit for the first time. This was Galileo, which spent some eight years examining the planet before its mission ceased in 2003. But, of course, this craft would definitely not be the last to embark on a mission to the gas giant.

In 2005, you see, it was decided that the Juno spacecraft would be sent to Jupiter under NASA’s New Frontiers program. New Frontiers also saw New Horizons arrive to orbit Pluto in 2015. And three years later, the OSIRIS-REx mission reached the asteroid Bennu, with its craft expected to return to Earth in 2023.

As mythology lovers will recognize, the Juno spacecraft is named after the Roman queen of the gods – a deity who also happened, it’s said, to be Jupiter’s wife. In fact, given one of the legends of ancient Rome, the name of the probe may appear to be particularly fitting.

In the tale, the god Jupiter conjures some clouds to surround him in an attempt to conceal his misdoings. However, his wife Juno demonstrates an ability to see through these clouds. And in doing so, she is able to catch a glimpse of the genuine character of her husband.

The relevance of Juno’s name hasn’t been lost on the principal investigator involved with the spacecraft, either. In 2011 the Southwest Research Institute’s Scott Bolton wrote on the NASA website, “[Jupiter] carries deep inside it the story of not only the solar system, but [also] of us. Juno is going there as our emissary to interpret what Jupiter has to say.”

The links between Roman mythology and Juno were acknowledged through a number of items in the spacecraft, too. In particular, some small Lego figurines intended to depict the Roman deities Jupiter and Juno were placed in the probe, while a third figurine stowed away represents Galileo. A plaque dedicated to the Italian astronomer is also on board.

This plaque was offered up by Agenzia Spaziale Italiana – Italy’s own agency dedicated to space – and depicts an image of Galileo. The commemorative object even includes a message that was once written by the astronomer himself in 1610 – so, at around the time when he apparently first set eyes on the Galilean Moons.

Image: Bill Ingalls/NASA via Getty Images

And on August 5, 2011, Juno finally embarked on its mission from Cape Canaveral in Florida. The spacecraft then traveled some 1.74 billion miles over five years, reaching the orbit of Jupiter on July 5, 2016 – the second craft ever to do so. From this point on, the probe subsequently began to undergo its analyses.

The primary purposes of Juno are to find out more about the make-up of Jupiter as well as to learn about magnetism and gravity there. The probe is also looking for signs of the planet’s beginnings along with investigating its core and taking note of winds, which can supposedly clock in at speeds of up to 384 miles per hour.

And Juno can be considered unique with regard to the way in which it functions. You see, in contrast to other spacecraft that have been sent to outer planets in the past, Juno runs on solar panels – a power source that is more typically utilized for satellites intended for Earth’s orbit and for reaching other inner planets.

What’s more, although Juno’s work is far from done, the probe has in many ways already proven a success. In June 2018 NASA decided to lengthen the craft’s mission, then, with its activities now scheduled to last until July 2021. Yet even without this extension, Juno has been a valuable asset.

“We have already rewritten the textbooks on how Jupiter’s atmosphere works,” Bolton told NASA in December 2018. “The second half [of the mission] should provide the detail that we can use to refine our understanding of the depth of Jupiter’s zonal winds, the generation of its magnetic field and the structure and evolution of its interior.”

Image: NASA/Jet Propulsion Laboratory-Caltech/Southwest Research Institute

And according to NASA, a number of Juno’s instruments have actually surpassed what was originally expected of them. An implement known as the Stellar Reference Unit, for example, was initially intended to compile information related to navigation. But that’s not all the unit has achieved; it has also now photographed the planet’s ring and has helped with understanding its belts of radiation, too.

Meanwhile, the so-called JunoCam imager was created as a means of connecting with us all on Earth. This device captures image data from the probe, with the information then uploaded to NASA’s website for people to interact with. It turns out, though, that the resulting pictures actually serve another scientific purpose.

“Our time-lapse sequences of images over the poles allow us to study the dynamics of Jupiter’s unique circumpolar cyclones,” Candy Hansen, Juno co-investigator at Tucson, Arizona’s Planetary Science Institute explained to NASA. “[And these have allowed us] to image high-altitude hazes. We are also using JunoCam to study the structure of the Great Red Spot and its interaction with its surroundings.”

Image: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

In addition, JunoCam has taken some spectacular images of Pluto throughout the course of the mission’s existence. And one thing that often stands out in these photos is the swirling appearance of the dwarf planet’s clouds – an indication of the often ferocious and relentless conditions that are experienced there.

Image: Oxford Science Archive/Print Collector/Getty Images

The image seen above, on the other hand, was snapped in May 2018 as Juno undertook a close fly-by of Jupiter. And in the moment captured by the picture, the probe was around 9,600 miles above the skies of the planet. The clouds seen in the shot are probably comprised of ammonia and possibly also of water as well as other unknown components.

Image: NASA/JPL-Caltech/SwRI/MSSS/Brian Swift/Seán Doran

The churning and colorful clouds of Jupiter undoubtedly make for a mesmerizing sight. And thanks to Juno and its JunoCam technology, NASA publishes the raw pictures online for the world to see. In these snaps, though, eagle-eyed viewers may be able to catch a glimpse of something unusual formed by the patterns.

Image: Captain Budd Christman, NOAA Corps

In fact, when the data was published, two men did indeed jump on a curious sight. In a certain image, you see, a formation of clouds looks to have settled into an interesting shape – one that appears to resemble a dolphin soaring above a swirling ocean.

Image: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt/Seán Doran

According to NASA, the photos that depict the dolphin shape were taken on October 29, 2018. In particular, the images were captured during one of Juno’s fly-bys – the 16th executed by the probe since the beginning of its mission.

Image: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstaedt/Sean Doran via Sci-News.com

And when the shots were made, Juno was apparently at a height of between 11,400 and 31,700 miles above Jupiter’s clouds. Yet these particular photos could only be seen thanks to the interactive nature of JunoCam. Two members of the public used the device’s data to develop the images, you see.

Seán Doran and Brian Swift are actually the ones responsible for the dolphin photos, although the men are not associated with the Juno mission or its primary functions. Rather, they simply acquired information from the JunoCam and proceeded to process it.

Image: via NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Sean Doran

And through creating these pictures, Swift and Doran have demonstrated the Juno mission’s importance beyond its immediate scientific commitments. Yes, while Juno is proving essential in the development of a wider understanding of Jupiter and its workings, it is also serving the valuable function of capturing the public’s imagination.

There could yet be more thrilling images in the offing, too, as Juno will remain operational until July 30, 2021. On this date, the spacecraft will leave the orbit of Jupiter and enter into the planet’s atmosphere, where it will then fall apart.

But until that time comes, there are still plenty of things for Juno to investigate. And even by this point in the mission, the data created by the craft has already changed how we understand Jupiter. As Scott Bolton remarked to Smithsonian magazine in 2018, “I’m in total wonder that we could have been so wrong [in the past].”

Image: The Hubble Heritage Team (AURA/STScI/NASA)

Plus, Juno’s findings may yet be more significant than we currently know. As there are reportedly billions of planets in the galaxy that bear similarities to Jupiter, understanding the nature of the gas giant could lead to a clearer idea of the make-up of more distant planets and solar systems. In other words, making sense of Jupiter is potentially essential to comprehending the rest of our galaxy.

And according to Bolton, finding out more about Jupiter is indeed crucial. He told Smithsonian magazine, “[Jupiter] grabbed most of the leftovers after the Sun formed. When we want to go back and try to understand how the planets were made – where the stuff that made us came from – Jupiter represents that first step.”