The solar system is a vast and mysterious place, full of surprising phenomena and mind-boggling discoveries. From planets that spin in unusual directions to moons that may harbor alien life, the solar system never ceases to amaze. In this collection of 25 strange facts, we’ll take you on a journey through some of the most bizarre and fascinating aspects of the celestial neighborhood we call home. Whether it’s a planet that’s colder than we could ever imagine, a moon that might hide an ocean beneath its icy surface, or a giant storm that has raged for centuries, you’ll find yourself marveling at the mysteries that lie beyond our planet.
1. Earth days are getting longer
For billions of years, the Earth’s rotation has been gradually slowing down, causing the days to grow longer—but don’t set your clocks just yet! This fascinating change occurs at an incredibly slow pace, about 1.8 milliseconds per century.
The phenomenon is largely influenced by tidal forces between the Earth and the Moon. As the Moon’s gravitational pull creates tides, it causes friction with the Earth’s oceans and crust, gradually transferring energy to the Moon and pushing it further away from our planet. In response, the Earth’s rotation slows, elongating the length of a day.
Around 1.4 billion years ago, a day on Earth lasted only about 18 hours. Fast forward to today, our 24-hour days are a result of this steady cosmic dance. However, these changes are so minuscule they go unnoticed within a human lifetime.
2. Moon is getting farther away 3.8cms every year
The Moon, Earth’s loyal celestial companion, isn’t as static as it seems. Every year, it edges slightly farther from us—about 3.8 centimeters (1.5 inches) away! While this might not sound like much, over millions of years, the effect is profound.
The process has been happening for billions of years. When the Moon first formed around 4.5 billion years ago, it was much closer to Earth—only about 25,000 kilometers (15,500 miles) away. Today, it sits at an average distance of 384,400 kilometers (238,855 miles).
3. A day is longer than a year on Venus
Venus, often called Earth’s twin because of its similar size and composition, has a surprising and mind-boggling feature: a single day on Venus lasts longer than an entire Venusian year!
Venus rotates incredibly slowly on its axis, taking about 243 Earth days to complete just one full rotation. Meanwhile, its orbit around the Sun—the equivalent of a year—takes only 225 Earth days. This means a “day” on Venus (from one sunrise to the next) outlasts its “year.”
4. Sun rises in the west and sets in the east on Venus
Venus rotates in the opposite direction of most planets, including Earth. This retrograde rotation means that if you stood on Venus, you’d see the Sun rise in the west and set in the east.
5. You can’t stand on Uranus & it smells like rotten eggs
Unlike Earth or Mars, Uranus is a gas giant primarily made up of hydrogen, helium, and methane. Beneath its thin upper atmosphere lies a dense layer of gases and ices, with no solid ground to stand on. If you tried to “land” on Uranus, you’d simply sink into increasingly dense and extreme layers of gas until being crushed by the intense pressure.
And then there’s the smell. Scientists have determined that Uranus’s upper atmosphere contains hydrogen sulfide—the same compound responsible for the stinky odor of rotten eggs. While there’s no air on Uranus for us to breathe (or smell), hydrogen sulfide is abundant in its clouds, making the planet a literal stinker in the solar system.
6. The whole of Mars is as cold as the South Pole
Mars’s frigid temperatures are primarily due to its thin atmosphere, composed mostly of carbon dioxide, which provides almost no insulation to trap heat from the Sun. While Earth has an average surface temperature of about 15°C (59°F), Mars averages a bone-chilling -60°C (-76°F), with temperatures plunging as low as -125°C (-193°F) at the poles during winter nights.
The coldest recorded temperature on Earth’s South Pole is about -89.2°C (-128.6°F), making it one of the few places on our planet that compares to the average conditions on Mars. However, unlike Earth’s poles, which warm significantly in the summer, Mars remains frigid year-round. Even on a sunny Martian afternoon near the equator, temperatures barely rise above 20°C (68°F), only to plummet drastically after sunset.
The extreme cold has significant implications for human exploration. Any water on Mars is either locked in ice or exists fleetingly as a thin film of liquid brine under very specific conditions. This makes surviving on Mars without advanced technology an incredible challenge.
7. Saturn’s rings are 90% water
The rings are composed of countless chunks of ice, ranging in size from tiny grains to massive boulders as large as a house. The purity of the water ice gives the rings their brilliant, reflective appearance, making them shine brightly against the dark backdrop of space. The remaining 10% is a mix of dust and other rocky materials.
But where did the rings come from? Scientists believe they could be the remnants of a shattered moon, a comet, or icy bodies that were torn apart by Saturn’s immense gravitational pull. These particles now orbit Saturn in a thin, flat plane, forming the stunning structure we see today.
Interestingly, Saturn’s rings are relatively young on a cosmic timescale—likely no more than 100 to 200 million years old. That means they didn’t exist during much of the solar system’s history and may fade away in the future as the particles either drift off into space or fall into Saturn’s atmosphere.
Despite being vast—stretching over 280,000 kilometers (175,000 miles) wide—the rings are surprisingly thin, just 10 to 100 meters thick.
8. Jupiter’s largest moon has a salty ocean that contains more water than on Earth
Ganymede, the largest moon of Jupiter and the biggest in the solar system, hides a remarkable secret beneath its icy surface: a vast salty ocean containing more water than all of Earth’s oceans combined.
This discovery was made through data collected by NASA’s Galileo spacecraft and the Hubble Space Telescope. Scientists believe that Ganymede’s subsurface ocean lies about 150 kilometers (93 miles) below its icy crust. The ocean itself is estimated to be around 100 kilometers (62 miles) deep—nearly ten times deeper than Earth’s oceans.
9. Mercury takes roughly three Earth months to orbit the Sun
This is an artist’s impression of Mercury. Mercury’s orbit is 88 days and it takes 59 days to rotate. In three months you could write a book, pass your driving test or learn basic guitar. It’s also the amount of time it takes Mercury to travel around the Sun. It’s the shortest orbit in the Solar System, because Mercury is the closest planet to the Sun. So, next time someone asks you when you’ll get around to mowing the lawn, tell them it’ll be in roughly one Mercurian year.
10. The Solar System is roughly 4.5 billion years old & Survive another 5 billion
About 4.6 billion years ago, something—perhaps a shockwave from a nearby supernova—triggered the collapse of its cloud. As it compressed, the material at its center heated up, forming the Sun. The remaining dust and gas flattened into a spinning disk, where particles collided and stuck together, eventually growing into the planets, moons, and other objects we know today.
The oldest objects in the Solar System are meteorites, which provide a “time capsule” of its earliest days. By studying these space rocks, scientists have pinpointed the age of the Solar System to around 4.56 billion years. Scientists estimate it will survive another 5 billion years.
11. Jupiter can fit all the planets in solar system
Jupiter, the giant of our solar system, is so massive that it could fit all the other planets inside it—and still have room to spare!
With a diameter of 139,820 kilometers (86,881 miles), Jupiter is more than 11 times wider than Earth and has a volume so vast that over 1,300 Earths could fit inside. When you combine the volumes of Mercury, Venus, Earth, Mars, Saturn, Uranus, and Neptune, they still fall short of Jupiter’s colossal capacity.
This incredible size is due to Jupiter’s composition. Made mostly of hydrogen and helium, it’s often referred to as a “failed star” because it has a similar makeup to the Sun but didn’t gather enough mass to ignite nuclear fusion.
12. The hottest planet is not the closest planet to the Sun
You might think that the closest planet to the Sun, Mercury, would be the hottest in our solar system. However, this is not the case. The title of “hottest planet” actually goes to Venus, which is the second planet from the Sun.
Mercury, despite its proximity to the Sun, doesn’t have a thick atmosphere to trap heat. It has extreme temperature fluctuations, with daytime temperatures soaring to about 430°C (800°F), but at night, without an atmosphere to retain heat, it can plummet to -180°C (-290°F).
Venus, on the other hand, has a thick atmosphere composed mostly of carbon dioxide, with clouds of sulfuric acid. This creates an intense greenhouse effect, trapping heat from the Sun and raising the surface temperature to a scorching around 465°C (870°F)—hotter than the surface of Mercury, even though Venus is farther from the Sun.
13. There are rocks on Earth that came from Mars and we didn’t bring them here
About 4.4 billion years ago, a massive impact struck Mars, sending debris from its surface into space. Some of these rocks, ejected from Mars, traveled across the void between planets, drifting through space for millions of years before being captured by Earth’s gravity.
Scientists have identified over 100 Martian meteorites that have fallen to Earth. These rocks are chemically distinct from Earth’s rocks, with certain elements and isotopes that match those found on Mars, such as a unique combination of isotopes of oxygen and trace gases, including noble gases like xenon.
One of the most famous Martian meteorites is ALH84001, discovered in Antarctica in 1984. This rock is particularly intriguing because it contains mineral features that some scientists have speculated could be signs of ancient life on Mars—tiny structures that resemble fossilized microorganisms. While the debate over whether life ever existed on Mars continues, the discovery of Martian meteorites on Earth provides a tangible connection between the two planets.
14. Jupiter has had the same ongoing storm for 300 years and counting
The Great Red Spot is a massive, swirling storm system located in Jupiter’s southern hemisphere. It is so large that it could easily fit three Earths within its boundaries. The storm has been observed since at least the 17th century, first spotted by astronomers in 1665, and its enduring presence has puzzled scientists for centuries. The giant hurricane-like storm has been raging nonstop for 300 years. This storm has fierce winds of around 270 miles per hour.
15. Neptune has the fastest wind speeds of 2100kms
Neptune, the farthest planet from the Sun, is not only a world of icy blue beauty, but also one with the fastest wind speeds in the entire solar system. Winds on Neptune can reach astonishing speeds of up to 2,100 kilometers per hour (1,300 miles per hour)—more than twice the speed of sound!
What makes Neptune’s winds so remarkable is their sheer velocity and consistency. While Earth’s wind speeds rarely exceed 400 kilometers per hour (250 miles per hour) during extreme weather events, Neptune’s winds are constantly whipping through its atmosphere at much higher speeds. The winds are not only fast, but also incredibly persistent, creating massive storm systems and violent weather patterns.
16. You grow as much as 5cm in space
If you ever dreamed of growing taller, space might be the place to do it! Astronauts in space can grow up to 5 centimeters (about 2 inches) taller than their height on Earth, and it’s all thanks to the microgravity environment.
On Earth, gravity constantly pulls down on our bodies, compressing our spine and limiting how tall we can be. Our vertebrae, the bones that make up the spine, are stacked together with small discs in between. These discs act as shock absorbers, but gravity keeps them pressed closely together. In space, however, the lack of gravity allows these discs to expand, which leads to a temporary increase in height.
While in space, astronauts experience microgravity, meaning the gravitational force is much weaker than on Earth. This weightlessness causes the spine to elongate and the discs between the vertebrae to stretch out, resulting in a height increase of up to 5 centimeters.
17. Space isn’t as far away as you might think
When we think of space, we often imagine it as an unreachable, distant frontier—light-years away from our daily lives. But in reality, space is closer than you might think. The boundary of space, known as the Kármán Line, is just 100 kilometers (62 miles) above Earth’s surface. That’s roughly the distance from New York City to Washington, D.C. or a two-hour drive on the highway.
To put this into perspective, many commercial airplanes fly at altitudes between 10 to 15 kilometers (6 to 9 miles), so astronauts are only about 10 times higher than where commercial airliners typically cruise. While 100 kilometers sounds like a lot, it’s still far less than the distance between major cities, and it’s something that modern space travel can reach in a matter of minutes. In fact, it only takes about 8 minutes for a rocket to launch from Earth and reach the edge of space.
18. There are 500,000 pieces of space junk floating around in outer space
Outer space may seem vast and empty, but it is far from free of clutter. Over 500,000 pieces of space junk are currently floating around Earth, creating a growing problem for satellites, spacecraft, and future space exploration.
Space junk, also known as space debris, includes defunct satellites, spent rocket stages, tools or equipment accidentally dropped by astronauts, and even tiny bits of paint and metal from previous collisions or spacecraft disintegration. These objects range in size from small screws and bolts to massive pieces of old satellites, and they can travel at speeds of up to 28,000 kilometers per hour (17,500 miles per hour)—fast enough to cause significant damage if they collide with operational satellites or spacecraft.
19. The footprints on the moon that won’t disappear for 100 million years
The Moon’s surface holds a special kind of history—footprints left by astronauts during the Apollo missions that will remain for millions of years. These footprints, left by Neil Armstrong, Buzz Aldrin, and others during their moonwalks, are unlikely to disappear anytime soon. In fact, they will likely remain intact for about 100 million years!
Why so long? The lack of atmosphere on the Moon is the key factor. Without air, wind, rain, or weathering, the Moon’s surface is incredibly stable. On Earth, footprints eventually disappear due to weather conditions and the constant movement of air and water, which erode surfaces over time. But on the Moon, there is no wind or rain to disturb these marks.
20. The mass of the sun takes up the majority of the solar system
The Sun is the heart of our solar system, and its mass is truly massive. In fact, 99.86% of the total mass of the entire solar system is contained in the Sun! This means that everything from the planets to the comets, asteroids, and space dust makes up only a tiny fraction of the solar system’s total mass. The Sun’s incredible mass is what gives it the gravitational power to hold the planets, moons, and other objects in orbit around it.
To put it into perspective, the Sun’s mass is approximately 330,000 times the mass of Earth. If you were to gather up all the planets in the solar system, including Jupiter, Saturn, and all the other gas giants, they would still make up only about 0.13% of the solar system’s total mass. Even Jupiter, the largest planet, has a mass that’s just about 0.1% of the Sun’s.
21. Jupiter’s magnetic field is bigger than the Moon
Jupiter is not only the largest planet in our solar system, but it also boasts one of the most powerful and expansive magnetic fields in the entire solar system—bigger than the Moon itself!
Jupiter’s magnetic field is about 14 times stronger than Earth’s and extends far beyond the planet itself. In fact, its magnetic field is so vast that it stretches nearly 1 million kilometers (about 600,000 miles) from the planet, which is roughly 10 times the diameter of Earth. But what makes it even more impressive is that this magnetic field is larger than the Moon! The Moon’s diameter is about 3,474 kilometers (2,159 miles), so Jupiter’s magnetic field extends far beyond the size of the Moon, creating a magnetic bubble around the planet that is truly enormous.
22. Neptune has only completed one orbit around the Sun since its discovery
Neptune, the farthest planet from the Sun, has a fascinatingly long orbit that makes it a unique case in the solar system. Since it was first discovered in 1846, Neptune has only completed one full orbit around the Sun—a journey that takes an astounding 165 Earth years to complete!
The reason for this long orbital period is Neptune’s great distance from the Sun—about 4.5 billion kilometers (2.8 billion miles) away. As a result, the farther a planet is from the Sun, the longer it takes to complete one orbit. While Earth takes just 365 days to orbit the Sun, Neptune’s orbit stretches over a period of 165 Earth years, meaning that since its discovery, it has only made one full trip around our star.
23. The Sun loses a billion kilos per second
The Sun, the life-giving star at the center of our solar system, is not just a constant source of light and energy—it is also losing mass at an incredible rate. Every second, the Sun loses around a billion kilograms (about 2.2 billion pounds) of its mass!
So, where does all that mass go? It’s not disappearing into thin air. Instead, it is being converted into energy through a process called nuclear fusion. Inside the Sun’s core, hydrogen atoms are fused together to form helium, a process that releases an immense amount of energy in the form of light and heat. While most of this energy is radiated outward, the fusion also causes a tiny bit of the Sun’s mass to be lost in the form of light, radiation, and solar wind.
The Sun has been undergoing this process for about 4.6 billion years, and it will continue for many billions more. But the loss of a billion kilograms per second might sound alarming, right? Fortunately, even though the Sun is losing mass, it will take billions of years before this affects its overall gravitational pull on the planets.
24. Uranus is the coldest planet in the Solar System
Uranus, the seventh planet from the Sun, holds a chilly title in our solar system—it is the coldest planet in the entire solar system. While many people might assume that Neptune, being farther from the Sun, would be the coldest, Uranus actually takes the crown with an average temperature of around -224°C (-371°F).
What makes Uranus so cold? Despite being slightly closer to the Sun than Neptune, Uranus has a much lower temperature, and scientists believe it’s because of a few unique factors. One major reason is that Uranus has a tilted axis—it’s tilted so much, in fact, that its poles point nearly directly at the Sun. This extreme tilt causes unusual seasonal changes and likely affects how heat is distributed across the planet.
25. Venus spins backwards & Uranus spins sideways
Our solar system is full of strange and unique planetary characteristics, and two planets in particular, Venus and Uranus, have peculiar rotations that set them apart from the rest of the planets.
Venus is unique because it spins backwards compared to most planets in the solar system. This means that if you were standing on the surface of Venus, the Sun would rise in the west and set in the east, the opposite of what we experience here on Earth. Most planets, including Earth, rotate in the same direction as they orbit the Sun, a phenomenon known as prograde rotation. However, Venus has retrograde rotation, meaning it spins in the opposite direction. This backward rotation may have been caused by a massive collision with another object early in the planet’s history, which could have knocked Venus off its normal rotational path.
On the other hand, Uranus has a highly unusual tilt—97.8 degrees from the plane of its orbit. Instead of spinning like most planets, Uranus essentially rolls on its side as it orbits the Sun, with its poles almost in the plane of its orbit. This means that Uranus spins sideways! This extreme tilt likely occurred due to a massive collision or gravitational interactions early in the planet’s history, causing its axis to be tilted in such a dramatic way. Because of this sideways spin, each pole getting around 42 years of continuous sunlight or darkness during its long orbit, Uranus experiences extreme seasonal variations.
