Space is an incredibly vast place, filled with mysteries that scientists have yet to fully explain. This is largely due to the immense size of space and the limitations imposed by physics, making it impossible to observe fully. For instance, understanding the current conditions of the Andromeda galaxy is challenging since the light we see from it is approximately 2.5 million years old, and that’s the galaxy closest to us.
Despite these challenges, humanity’s tenacity has allowed us to witness and understand some amazing phenomena within the parts of space we can observe. Scientists have identified the largest structure in the known universe, discovered a peculiar interstellar boundary, and solved numerous previously unsolvable puzzles within our own solar system. Let’s explore some of the significant mysteries of the planets in our solar system that have been unraveled.
AI debunks a long-standing Mars mystery
The concept of colonizing Mars has transitioned from science fiction to a feasible prospect that NASA is seriously considering, with plans to potentially send astronauts to the red planet in the 2030s. This next step in space exploration also involves Elon Musk’s SpaceX, which aims to establish a large Mars colony. With the planet becoming a hot topic in cosmic real estate, there is significant interest in discovering water on Mars, which would greatly aid colonization efforts.
In 2025, researchers from the University of Bern and Brown University utilized artificial intelligence to examine one of the most promising signs of water on Mars: the mysterious streak formations in the Olympus Mons region. These patterns, first discovered by NASA’s Viking project in the 1970s, appear in various parts of Mars and their ever-changing appearance led scientists to hypothesize that they might be watercourses formed by salty water flowing on the planet.
Unfortunately, the study’s results indicate that briny water is not responsible for the streaks. After analyzing extensive data and images from multiple agencies’ observations of Mars using a machine learning algorithm, it was determined that the patterns are most likely caused by wind and other environmental factors moving the dust around.
One plucky probe uncovered Mercury’s mysteries
Many aspects of Mercury remain a mystery to science. Due to its close proximity to the sun, the planet is extremely difficult to reach and observe even today.
Although we’ve known about Mercury for at least 5,000 years, thanks to records from the ancient Sumerian civilization, detailed knowledge about it remained elusive until we crashed a probe into it. In 2004, NASA’s Messenger mission launched a probe that orbited Mercury from 2011 to 2015, ultimately crashing onto the planet. During its mission, it provided data that illuminated many aspects of Mercury that had puzzled researchers since the 1970s when the Mariner 10 probe conducted the first flyby.
Scientists were aware that Mercury, like other planets, is gradually cooling. However, Messenger’s data revealed that this process is occurring at a relatively fast pace, shrinking the planet’s diameter by about 8.5 miles over its lifetime. We also learned that Mercury possesses its own, skewed magnetic field, and its peculiar patchwork surface is a combination of newer terrain and older parts of the planet’s interior that have been pushed to the surface.
Scientists find water on Mars
Interestingly, the previous entry about Mars doesn’t imply that there’s no water on the planet at all. In fact, a group of geophysicists analyzing data from NASA’s InSight lander discovered evidence suggesting that Mars might have an abundance of H2O.
The InSight mission, which took place from 2018 to 2022, focused on studying the planet’s depths, including its tectonic activity and structural composition. InSight also found signs of water deep within Mars — enough to potentially submerge the entire surface under a mile-deep ocean. This discovery implies that Mars didn’t lose all its water when its surface dried up around 3 billion years ago.
From a habitability perspective, the depth of this reservoir unfortunately makes it virtually inaccessible for potential settlers. While this may be disappointing, the discovery of water provides a significant opportunity to explore another intriguing scientific question: whether there’s life on Mars. “Establishing that there is a big reservoir of liquid water provides some window into what the climate was like or could be like,” Professor Michael Manga of the University of California, Berkeley told BBC. “And water is necessary for life as we know it. I don’t see why [the underground reservoir] is not a habitable environment.”
Data from Voyager 2 solves long-standing Uranus mysteries
Voyager 2 is one of the great success stories of space exploration, continuously providing valuable information about Saturn, Jupiter, Uranus, and Neptune — all of which it has flown by and studied.
Regarding Uranus, the 1986 Voyager 2 flyby introduced numerous mysteries about the icy planet’s atmosphere, such as an unusual lack of plasma and perplexing radiation belts with no apparent energy source. This led to the assumption that the planet’s magnetosphere was misaligned, puzzling scientists for decades until the same data that introduced these mysteries ultimately offered a solution. In 2024, a new analysis of the 1986 data revealed that the timing of the Voyager 2 flyby was particularly unfortunate. Just before the probe’s visit, a powerful solar wind struck the planet, temporarily disrupting its magnetosphere and resulting in skewed data.
Dr. Linda Spilker of the NASA Jet Propulsion Laboratory was one of the scientists analyzing the 1986 data. As she told the NASA website, she was pleased with the explanations the 2024 data-mining uncovered. “The flyby was packed with surprises, and we were searching for an explanation of its unusual behavior,” she said. “The magnetosphere Voyager 2 measured was only a snapshot in time. This new work explains some of the apparent contradictions, and it will change our view of Uranus once again.”
Scientists finally figure out Jupiter’s pulsating aurora phenomenon
Auroras are an impressive sight on Earth, attracting tourists to Nordic countries like Finland to witness them. The phenomenon occurs when solar winds carry particles released by the sun’s electromagnetic activity into Earth’s atmosphere, where they collide with nitrogen and oxygen atoms, releasing energy that makes the atoms glow with vibrant colors. While the science behind it is relatively simple on Earth, auroras on other planets, such as Jupiter, are far more complex and challenging to understand.
Jupiter’s poles feature peculiar, pulsating auroras with strong X-ray emissions. These auroras occur frequently and are significantly more powerful than their Earthly counterparts. They can differ between the planet’s North and South poles and contradict the common understanding of auroral mechanics, as science couldn’t decipher the mechanism behind these X-ray pulses.
In 2021, four decades after they were first observed, a study successfully explained Jupiter’s X-ray auroras by combining data from NASA’s Juno spacecraft and the European Space Agency’s XMM-Newton space telescope. It turns out that an interaction between solar winds and changes in Jupiter’s magnetic field creates a curved, electromagnetic ion cyclotron wave that guides charged ions to the planet’s atmosphere in the polar regions. The impact of their rapid arrival generates a burst of X-rays, which in turn forms the aurora.
Jupiter’s geometric storms can likely be solved by a 19th-century scientific experiment
Jupiter’s most famous storm is its Great Red Spot, a massive anticyclone that is as mysterious as it is powerful. However, it’s not the only strange phenomenon occurring on the planet’s surface.
One of the more recent mysteries involves Jupiter’s geometric cluster storms, discovered in 2019 through NASA’s Juno mission. The planet’s poles are surrounded by large cyclones, some reaching up to 4,350 miles in diameter, but their size isn’t the most intriguing aspect — it’s how they interact. The cyclones, which can persist for months, often form various geometric patterns, clustering them together.
While this may seem like a major mystery, it turns out that science might have already resolved the puzzle of geometric cyclones … in the 19th century. According to Juno mission team member and Caltech professor Andrew Ingersoll and his colleagues, Jupiter’s geometric storms bear a striking resemblance to an 1878 experiment conducted by physicist Alfred Mayer. Mayer’s experiment found that magnets floating in water configured themselves into geometric patterns. Mathematical physicist Lord Kelvin later developed a mathematical model based on this experiment, and in 2020, it became an essential building block for solving one of Jupiter’s mysteries. While the theory isn’t completely confirmed, and some secrets behind the geometric storms remain, we now have a plausible explanation for why they might behave like synchronized dancers.
NASA figures out the secrets of Jupiter’s volcanic moon
For a long time, one of Jupiter’s moons stood as one of the most enigmatic celestial objects in the solar system. Jupiter’s moon Io is a scarred, scorching place with a surface riddled with hundreds of volcanoes. Io’s volcanic activity is off the charts, and for decades, scientists had little understanding of how it functioned. Was a giant hidden magma reservoir feeding the numerous surface volcanoes? Was Io plagued by a case of planetary acne, with each volcano’s eruptions fueled by its own underlying magma pool?
Linda Morabito of NASA’s Jet Propulsion Laboratory discovered Io’s volcanic unrest in 1979, but it took until the Juno flybys of 2023 and 2024 to truly comprehend the underlying causes. The explanation is dramatic, to say the least: Io orbits Jupiter in a tight, elliptical cycle lasting just 42.5 hours. This causes the gas giant’s gravitational pull to continuously squeeze the moon and release its grip.
This immense force generates substantial heat, which in turn melts parts of the moon, sustaining its volcanic activity. Each volcano indeed has its own magma reservoir. It’s surprising that Io has avoided a “sea of magma under the surface” scenario despite the forces involved, and researchers are eager to apply this discovery to their studies of other celestial bodies.
The waters of Venus may have evaporated into space
Scientists have long suspected that Venus, like Earth, once held water. However, something happened, transforming it into the hot and hellish planet we see today. But what?
In 2024, a study presented a convincing (and terrifying) sequence of events that could have led to Venus’s current state. According to the study, large bodies of water that Venus may have once had succumbed to an extreme version of the greenhouse effect. This phenomenon occurs when greenhouse gases (such as carbon dioxide) trap heat near the planet’s surface, significantly warming it.
On Earth, the natural greenhouse effect is a life-sustaining force that maintains a comfortable surface temperature. However, human-caused greenhouse gas emissions have disrupted this process, resulting in rising temperatures. Venus, as the study suggests, may have experienced a far more severe version of this: Over time, the planet’s carbon dioxide levels rose to absurdly high levels, heating the planet until all its water evaporated. The evaporated water reacted with HCO+ ions in a process called HCO+ dissociative recombination, which broke the evaporated water molecules, reformed them as carbon monoxide and hydrogen, and ultimately expelled the hydrogen atoms from the atmosphere at high speeds. This process removed a crucial building block of water, stripping the planet of its H2O.
Saturn’s Earth-sized white spot storms are likely kept in check by moisture
We’ve already discussed Jupiter’s Great Red Spot, undoubtedly the most powerful player in the solar system’s planetary storm game. However, it’s not the only contender in the supersized storm category.
Saturn experiences periodic “white spot” storms roughly the size of Earth (though they can stretch significantly), occurring approximately every 20 to 30 years and lasting for months. Researchers first discovered them in 1876, and they quickly became a mystery because no one could determine why they took decades to develop.
In 2015, researchers discovered that the most likely “control system” behind the white spot storms is one that is quite familiar to Earthlings: water. Most of Saturn consists of light helium and hydrogen, so heavier moisture tends to reside lower in the gas giant’s atmosphere. This moisture layer, researchers believe, acts as a sort of filter that prevents warm gas from rising freely during the convection process crucial to atmospheric movements leading to storms. Without this moisture, the planet’s gases could move more freely, and storms would form more easily.
The very existence of Neptune as a planet was solved with math 200 years after its discovery
Numerous planetary mysteries have been unraveled through the careful application of scientific tools and knowledge. However, Neptune is the only planet in our solar system discovered through the power of mathematics.
After Pluto was demoted to dwarf planet status in 2006, Neptune became the most distant planet in the solar system. Unlike its seven siblings, it cannot be observed without special equipment, and its location and 165-year orbit can make it appear deceptively stationary, leading early astronomers to mistake it for a star. This was how astronomer and mathematician Galileo Galilei classified Neptune in 1612 and 1613, and it remained so until 1846.
Neptune’s “origin story” as a planet began when scientists noticed that Uranus, discovered in 1781, had an inconsistent orbit around the sun. Suspecting that other forces were at play, mathematician Urbain Joseph Le Verrier calculated the size and location of an unknown celestial object that could affect Uranus’s path. After Johann Gottfried Galle at the Berlin Observatory received Le Verrier’s calculations, he almost immediately discovered the eighth planet from the sun.
Saturn’s rings may have been formed when the planet’s gravitational pull tore a moon apart
Saturn may not be the largest planet in our solar system, but its stunning rings certainly make it a contender for the most visually captivating. Unsurprisingly, these rings are also one of the most enticing mysteries Saturn has to offer. The seven rings encircling the gas giant have intrigued scientists for centuries, even though their composition is no more mysterious than countless, differently-sized pieces of rock and ice orbiting the planet in a visually pleasing formation.
Some scientists believe the rings are composed of comets and other small celestial objects that Saturn’s gravity captured and broke down between 100 and 400 million years ago. Others suggest the rings could be as old as the planet itself — 4.5 billion years. However, a 2022 study proposed another intriguing explanation, one that could also account for Saturn’s relatively large axial tilt.
By analyzing gravitational data from NASA’s Cassini spacecraft, a team from MIT determined that Saturn’s rings are “only” 100 to 200 million years old and are remnants of a former moon that was torn apart when it ventured too close to the planet’s gravitational pull. Such an event could have also contributed to Saturn’s slight axial tilt, throwing it slightly out of sync with Neptune.
