Our solar system is filled with a star, eight planets, some dwarf planets, and lots of comets and asteroids. A few centuries ago, people thought that more than eight planets existed out there. They erroneously labeled asteroids as planets, discovered nonexistent planets, and predicted the existence of some other planets.

Some of these predictions came true—like Neptune, which was discovered after its existence was predicted. However, many more have remained hypothetical. We believe that some of these planets could exist, while we know that others do not. Nevertheless, we should always keep our fingers crossed.

10 Vulcan

Vulcan is a hypothetical planet believed to lie between Mercury and the Sun. A few centuries ago, the planet was proposed after astronomers observed that Mercury had slightly changed its orbit with every revolution around the Sun.

In 1859, French astronomer Urbain-Jean-Joseph Le Verrier suggested that this was caused by the gravitational pull of an undiscovered planet lying between Mercury and the Sun. He called it Vulcan after the Roman god of blacksmithing. Le Verrier added that the planet could not be spotted because it was too close to the Sun.

A year later, amateur astronomer Edmond Modeste Lescarbault claimed to have spotted a small black dot near the Sun. Le Verrier said the dot was the planet Vulcan. Other astronomers later claimed to have spotted the elusive planet, although some insisted that they couldn’t see it.

Vulcan was soon considered the first planet of the solar system despite the lack of concrete evidence. This was probably because Le Verrier was an authority figure in astronomy. Thirteen years earlier, he had proposed Neptune after observing that an undiscovered planet was altering the orbit of Uranus. Besides, Vulcan’s existence was the only explanation for Mercury’s haphazard orbit.

This changed in 1915 when Albert Einstein’s Theory of General Relativity trashed every claim about the existence of Vulcan. Einstein said that massive objects like the Sun could bend time and space. Mercury’s orbit often changed because it was traveling through a “distorted space-time” caused by its closeness to the Sun.^[1]

9 Tyche

Tyche is a hypothetical planet lying somewhere in the Oort cloud at the edge of the solar system. The planet was proposed in 1999 by three astrophysicists from the University of Louisiana. The trio suggested that Tyche is the size of Jupiter, has three times the mass of Jupiter, and orbits the Sun once in 1.8 million years.

The astrophysicists proposed Tyche to explain the existence of long-period comets. These comets take over 200 years to complete an orbit round the Sun. Astronomers used to believe that long-period comets appeared from random locations in the solar system.

However, the astrophysicists say that the comets actually come from the Oort cloud and are flung toward the Sun by the gravitational force of Tyche. NASA used its Wide-field Infrared Survey Explorer (WISE) telescope to search for Tyche between 2012 and 2014. It found nothing.^[2]

8 Planet V

A barrage of asteroids hit the surfaces of Mercury, Venus, Earth, Mars, and the Moon 3.8 billion years ago. Scientists call that barrage the Late Heavy Bombardment (LHB). However, they cannot confirm where those asteroids came from.

Some scientists have suggested that the asteroids came from the remnants of Planet V, which lay between Mars and the asteroid belt that separates Jupiter from Mars today.

Scientists think that Planet V was smaller than Mars, which may explain why its orbit was heavily altered by the gravitational pull of Jupiter and other outer planets. Planet V soon became unstable and strayed into the asteroid belt, flinging asteroids toward Mars and the other inner planets. Planet V itself was later flung into the Sun or far into the solar system.

Alternatively, Planet V could have just steered clear of the asteroid belt and crashed into another planet. Some astronomers think it crashed into Mars and created the Borealis Basin, which covers 40 percent of Mars. If that happened, the asteroids that crashed into the inner planets were probably fragments flung into space during the collision.

Other astronomers say that the hypothetical Planet V never existed. They think that the LHB occurred after Jupiter and Saturn changed their orbits and flung asteroids from the asteroid belt toward the inner planets. Others say that the LHB was caused after the gravitational pull of Mars broke a large asteroid apart.^[3]

7 Theia

Scientists used to believe that the current Earth and Moon were created after a planet they called Theia slammed into an early Earth. The collision caused the smaller Theia to break up, sending fragments into space. One of these fragments became the Moon.

Scientists disproved this theory after tests on Moon rocks revealed that the Earth and Moon were made from the same material. These days, scientists believe that Theia slammed into an older Earth about 4.5 billion years ago. Both planets mixed together to create Earth. A fragment of Earth later broke off to form the Moon.^[4]

6 Phaeton

Astronomers believed there was an undiscovered planet between Mars and Jupiter until quite recently. The existence of the hypothetical planet seemed truer when Giuseppe Piazzi discovered what was considered to be planet Ceres in 1801. A year later, Heinrich Olbers discovered what was thought to be planet Pallas.

Olbers soon realized that Ceres and Pallas used to be part of the same planet. This belief was reinforced when planets Juno and Vesta were discovered. Ceres, Pallas, Juno, and Vesta were later reclassified as asteroids and considered remnants of a hypothetical planet called Phaeton.

Astronomers of the day thought that Phaeton had broken up and created the four large asteroids and every other one in the asteroid belt between Mars and Jupiter today.

Some astronomers thought that Phaeton had broken up after it exploded, was destroyed by Jupiter, or had smashed into another celestial body. Some think that this celestial body is Nemesis, a hypothetical star that was believed to be in our solar system.

However, today’s astronomers have disproved the existence of Phaeton. They say that the asteroids in the asteroid belt have always been asteroids. They were stuck between Mars and Jupiter and would have formed into a planet if it weren’t for Jupiter’s massive gravitational pull that kept them apart.^[5]

5 Nibiru

Nibiru is a hypothetical planet supposedly lurking somewhere in our solar system. While NASA says that it does not exist, conspiracy theorists insisted that it was real and would slam into the Earth in the year 2012.

For the record, Nibiru is also called Planet X and should not be confused with the hypothetical Planet Nine that is also called Planet X. We will get to Planet Nine shortly.

Nibiru was first proposed by Zecharia Sitchin in his 1976 book, The Twelfth Planet, where he claimed that it orbited the Sun every 3,600 years. Many years later, self-proclaimed psychic Nancy Lieder declared that aliens had warned her that Nibiru would slam into the Earth in 2003. Later, she changed the date to 2012.

In 2011, Comet Elenin passed by Earth and broke apart after flying too close to the Sun. Hard-liners insisted that the comet was planet Nibiru on its approach to crash into Earth. The fact that we are reading this article means that planet Nibiru probably doesn’t exist. Or it just missed Earth and will be returning in 3,600 years.^[6]

4 Planet Nine

Planet Nine is another hypothetical planet lurking somewhere in our solar system. Unlike Nibiru, NASA and astronomers from the California Institute of Technology think that Planet Nine could exist, although there is no verifiable evidence that it does. Astronomers speculated the existence of Planet Nine after observing the irregular orbits of five solar objects far beyond Neptune.

Astronomers think that Planet Nine is the same size as Uranus or Neptune, has a mass 10 times that of Earth, and is 20 times farther from the Sun than Neptune. They believe that Planet Nine takes 10,000–20,000 years to complete a revolution around the Sun.^[7]

3 Counter-Earth

In the fourth century BC, Greek philosopher Philolaus proposed the existence of a planet that he called Counter-Earth. He believed that Counter-Earth was always on the opposite side of the solar system from Earth. This meant that the Sun, Earth, and Counter-Earth would always be on the same line.

Philolaus believed that Counter-Earth was invisible from Earth because Counter-Earth was always obscured by the Sun. Today, we know that it could have never existed. If it had, we would have seen it from Earth because every planet in the solar system is affected by the gravitational pull of other planets.

The gravitational pull of Mercury and Venus would have altered the orbit of Counter-Earth and shifted it from its position on the opposite side of the solar system. This would have made it visible from Earth. Counter-Earth would have strayed closer to Earth over time, and both planets would have eventually met.

One of two things would have happened when they met. Earth and Counter-Earth could have collided to form a new Earth. Or they could have missed each other. If they had, their gravitational pulls would have been so great that they would have been thrown into new orbits.^[8]

2 An Unnamed Planet

Planets are often unstable after their creation. They will frequently change orbits because their orbits are continuously altered by the gravitational pull of other planets. In 2005, three groups of researchers used this theory to propose the Nice Model of the formation of the solar system.

In the past, the gravitational pull of other planets made Uranus and Neptune swap orbits and sent Jupiter and Saturn farther away from the Sun. Jupiter also supposedly moved closer to the Sun before returning to the outer solar system.

The Nice Model was accepted as true until it was partly disproved in 2011. At that time, some scientists said there had to be a fifth planet between Mars and Jupiter for it to be true. However, they added that the planet was probably flung out of the solar system by the gravitational pull of either Saturn or Jupiter.

In 2015, other scientists disproved the Nice Model because it did not explain the creation of the inner planets (Mercury, Venus, Earth, and Mars). They said that Jupiter would have cleared the inner planets, particularly Mercury and Mars, if it had ever strayed into the inner solar system.

The four inner planets would have formed long after the four outer planets if the Nice Model were true. Or they could be the survivors of Jupiter’s apocalypse. This means that the other inner planets were flung farther into the solar system along with one or two planets from the outer solar system.^[9]

1 Tiamat

The Sumerians believed that a planet called Tiamat lay between Mars and Jupiter. However, there is some debate about where this planet is today. In his book, Dark Matter, Missing Planets and New Comets, Tom van Flandern claimed that the planet was destroyed 65 million years ago and became the asteroid belt.

Zecharia Sitchin disputed this in his books The Twelfth Planet and The Cosmic Code. Instead, he declared that Tiamat had changed orbit and is now Earth. Sitchin said that Tiamat changed orbit after colliding with a hypothetical planet called Marduk and its three moons.

Sitchin claimed that the collision formed a new planet that broke in half. Two chunks of it moved closer to the Sun to become the Earth and the Moon while leftover debris became the asteroid belt. Sitchin added that Tiamat’s former moons were also flung into new orbits. He believes that one of the moons crashed into Mars and created the great rift.^[10]

Astronomy is a fascinating thing. The more you learn about the universe, the more you realize there is to know. Discoveries often throw up more questions than they do answers.

But the great secrets of outer space are not all hidden in black holes and far-off galaxies. Some of them are a lot closer to Earth than you might imagine. From the ice dunes of Pluto to Jupiter’s luminous moon, the solar system is home to all kinds of elusive and mind-boggling phenomena. This list looks at some astonishing secrets of the solar system that scientists are in the process of unraveling.

10 Hypothetical Planets That Could Exist In Our Solar System

10 Strange Things Dwell in the Clouds of Venus

The skies of Venus are teeming with strange and elusive things. Scientists say we can learn a lot from the clouds that swarm over our neighboring planet. Astronomers reckon Venus was once a lot like Earth. Its surface was covered in great lakes and oceans. But toxic gases and environmental warming scorched the planet, turning the wetlands of Venus into the arid landscapes we see today.

But perhaps, scientists wonder, was there once life on the nearby planet? And, if so, could that life have survived by ascending into the clouds? Around thirty miles (fifty kilometers) above the surface of Venus, the temperature and pressure are said to resemble those here on Earth.

Entrepreneur Peter Beck is obsessed with Venus. In 2023, his company Rocket Lab plans to send a robot to search the clouds of Venus for signs of extra-terrestrial life. The Californian spacecraft firm hopes to find living beings floating miles above the barren ground.

“We’re going to learn a lot on the way there, and we’re going to have a crack at seeing if we can discover what’s in that atmospheric zone,” Beck explained. “And who knows? You may hit the jackpot.”

9 Space Hurricane Looms over Earth

In 2014, scientists noticed a strange vortex swirling high above the North Pole. The unusual spiral of auroral light measured over 600 miles wide, dazzling the skies for eight hours before fading into the night. But, until recently, researchers struggled to explain what the giant patch of light was and why it was there.

Now, physicists at Shandong University in China have managed to shed some light on the situation. Using satellite data collected during the Cold War, Qing-He Zhang explained that the mysterious ‘space hurricane’ was a large spiral of electrically charged gas. Celestial whirlpools like the one seen in 2014 are created by showers of electrons ejected from the sun. The minuscule particles cascade through the Earth’s magnetic field, crashing into gas atoms in the upper atmosphere and releasing bright flashes of light. Zhang and his team reckon space hurricanes may have occurred before 2014, but this is the first time scientists have identified one.

8 Methane Points to Life on Mars

Is there life on Mars? David Bowie famously sang about the prospect of aliens dwelling on the Red Planet. Now, we have evidence that there may be creatures up there.

Astronomers have detected methane on Mars several times. The presence of the gas has led some scientists to speculate that life could exist on the Red Planet. On Earth, living organisms are the most common producers of methane. It would follow that it could be the case on other planets too. Every time new scientists find new evidence of Martian methane, they come one step closer to discovering if anything lives on our neighboring planet.

In 2019, NASA’s Curiosity vehicle uncovered a surge of methane gas in Mars’ atmosphere. The record-high spike was detected inside Gale—a 154km-wide (96 mi) crater that the rover has been scoping out since it landed in 2012. This is not the first time Curiosity has come across spikes of methane. The exploration rover detected gas twice from 2013-14, but these were significantly lower than the latest measurements.

The remarkable discovery hints at extraterrestrial life, but it is not definite proof of Martian microbes. Methane is also produced through geological processes, like certain rock minerals reacting with water. Astronomers need to gather more evidence before they can identify the source of the gas.

7 Ice Dunes Spotted on Pluto

The surface is Pluto is a strange and mysterious place. Scientists used to believe that the dwarf planet was soulless and barren. They reckoned the atmosphere was nowhere near thick enough for dynamic features to form. However, recent footage from NASA’s New Horizons mission has proved otherwise. The photographs reveal that Pluto is teeming with fascinating geographical oddities.

Dunes of frozen methane billow across the Sputnik Planitia plains. A vast range of mountains of water ice stretches alongside them, each jutting out around 5km (3mi) high. The mounds are formed from tiny crystals of methane—around the same size as a grain of sand—that have been whipped up by glacial winds from the nearby mountains. The dunes are also thought to contain frosted nitrogen crystals.

Pluto is the latest addition to a growing list of celestial bodies on which astronomers have spotted dunes, which includes Venus, Titan, and the comet 67P.

6 Mysterious Hum Detected on Mars

When NASA launched its InSight lander to study Mars in 2018, nobody expected it to find the planet humming. But that is precisely what the spacecraft detected. According to InSight’s readings, the Red Planet is emitting an endless hum punctuated by quakes and tremors. And nobody can figure out why.

The craft is equipped with a high-precision seismometer and a range of detectors. Researchers say that data from InSight has already revealed an enormous amount about the planet’s structure and magnetic field. Since it landed, the lander has recorded over 450 cases of seismic activity – or, as some experts call them, ‘marsquakes.’ Unlike Earth, Mars has no tectonic plates, which means scientists are still trying to work out exactly how the quakes are caused.

But the most surprising of InSight’s discoveries is the mysterious Martian hum. The seismic signal buzzes away at 2.4 Hz and seems to grow louder when the planet quakes. Researchers are unsure about the origins of the unexpected throb, although they have ruled out the wind.

5 Methane Rain on Saturn’s Largest Moon

Titan, the largest of Saturn’s moons, has several unusual weather patterns. Apart from Earth, it is the only known body in the solar system where liquid rain falls on a solid surface. However, unlike Earth, the rainfall on Titan is infrequent. According to NASA’s Cassini orbiter, there are areas of Titan that only receive rainfall around once every thousand years—and instead of water, it rains methane.

It might not rain often on Titan, but when it does it pours. Meters of rainfall can come cascading down in one shower. This severe battering etches deep river channels into the surface of the moon. Astronomers have even discovered vast lakes and seas of liquid methane.

One of the mysteries puzzling scientists is the lack of cloud cover around the North Pole. During a study of sunbeams on the moon, scientists recently observed rainfall during Titan’s summer for the first time. However, they were stumped why they had not spotted any clouds. Cracking this conundrum could expand our understanding of weather patterns in general. But for now, it remains unknown.

4 Europa, Jupiter’s Icy Moon, Might Glow in the Dark

A new study suggests that one of Jupiter’s moons might glow in the dark. Researchers reckon that Europa could emit a greenish glow caused by the intense radiation from Jupiter’s magnetic field.

Europa is known for being coated in a thick layer of ice. The frosted moon faces an endless barrage of electrons. When the charged particles slam into Europa’s icy surface, they transfer some of their energy to the molecules in the ice. The energized molecules then release that energy as light, which scientists say could give the moon an eerie shimmer.

3 Strange Mass Hiding Under the Surface of the Moon

Beneath the largest crater in the solar system lies a giant hunk of metal and no one is sure what it is doing there. The elusive mass is thought to be around five times the size of the Island of Hawai’i, nestled under the South Pole-Aitken basin on the far side of the moon.

The crater is roughly oval-shaped, over 1,200 miles wide, and many miles deep. Astronomers reckon it was created four billion years ago. But the mass itself lies hundreds of miles underground. Scientists discovered the metal anomaly during a study of the moon’s surface and gravitational field.

Scientists are keen to discover the origins of this puzzling underground lump. One theory states it could have come from the asteroid that blasted the crater into the moon’s surface. The core of a meteorite is often made of iron-nickel alloy. Computer simulations have shown that this metallic core could have become lodged in the moon’s mantle. Another suggestion is that the mass is related to oceans of liquid magma cooling down and solidifying.

2 The Mystery of Rust on the Moon

As you are surely aware, iron starts to rust after long periods around oxygen and water. So you can imagine the surprise when astronomers discovered rust on the moon. Using data from India’s Chandrayaan-1 mission, Hawai’ian researcher Shuai Li showed clear signs of iron oxide or, as it is more commonly known, rust on the lunar surface.

At first, scientists were flummoxed by Li’s findings. How does rust form in a place without any oxygen? On top of that, solar winds subject the moon to an onslaught of hydrogen atoms. Hydrogen is known to give away its electrons, making it even more difficult for iron to oxidize. Rust on the moon should be impossible, and yet the evidence was beyond dispute.

Then came the breakthrough. Astronomers discovered that the answer lies in the shape of the Earth’s magnetic field. Earth is also constantly whipped by solar winds, which squash and distort the planet’s magnetic field. This causes the part of the field furthest from the sun to stretch backward, like a tail. This magnetotail extends 240,000 miles (385,000 kilometers) into space.

During its orbit of the Earth, the moon dips briefly inside the magnetotail. At this point, the Earth shields the moon from its usual bombardment of hydrogen. The magnetic field also deposits small amounts of oxygen on the surface of the moon. For just a moment, the conditions are right for rust to form.

1 ʻOumuamua, the Solar System’s first known Visitor

In 2017, a giant cigar-shaped structure became the first known interstellar object to visit the solar system. The strange visitor left scientists scratching their heads as it hurtled around the sun at 196,000 miles per hour.

Astronomers know that ʻOumuamua – whose name means “a messenger from afar arriving first” in Hawai’ian – sped into the solar system from somewhere else in space. They reckon it measures around half a mile (800 meters) in length and a tenth of that in width. They predict that the cosmic traveler should tumble through the sun’s orbit for a while before shooting off again.

Other than that, little is understood about the elusive wandering object. According to NASA, scientists have no real idea what ʻOumuamua looks like, what it is made from, or from where it came. There a currently an array of telescopes around the world and in space trailing the mysterious visitor.

10 Radical Ideas To Colonize Our Solar System

Sci-fi horror is a burgeoning movie and TV genre that, in a sense, is a testament to humanity’s fear of the unknown. And yet, like Manifest Destiny that drove American settlers westward, the compulsion to explore it burns strong in modern society. Some byproducts in our race to space have bettered our lives: take baby formula or smartphone cameras (though unfortunately, unlike popular belief, Velcro and Tang were not, in fact, created by NASA). But the more we learn what’s out there, the more true horrors emerge to justify our existential dread. Take, for instance, the following 10 Frightening Facts About Our Solar System that will forever change your perception of where we live and how our tiny little blue planet has made it this far.

10 Space Dinosaurs On The Moon

There hasn’t been a crewed landing on the moon since 1972. So what the heck is actually up there? Luckily, we have technology like NASA’s Lunar Impact Monitoring telescope and NASA’s Lunar Reconnaissance Orbiter. The Orbiter has been circling the moon and sending back measurements since 2009. And part of what scientists found was actual dinosaur bones sent off Earth from the meteors that led to their downfall.

The moon has no atmosphere to create wind to erode them, and thus they remain in perfect condition. Who knows what discoveries to help complete our fossil record remain there, tantalizingly out of reach. And with how surprising it was to find dead dinosaurs on the moon, let’s not rule out living ones…

9 Pluto isn’t a Planet, But if it Was

We’re sorry if this is where you hear the final verdict on the infamous debate: Pluto is and always has been a dwarf planet. We’re also sorry that the American Education System has failed you because there’s a lot more in our Solar System than just eight planets and one dwarf planet. There are four more officially classified dwarf planets in our Solar System: Ceres, Haumea, Makemake, and Eris, and they have always been there.

We’ve known about Ceres since the 1800s! Makemake even has its own moon, while Haumea has two! Additionally, there are dwarf planet candidates. Possibly as many as 200 in the Kuiper belt and over 10,000 in the region beyond. Scientists believe that some larger moons like Neptune’s Triton are dwarf planets caught in the planet’s orbit. If we don’t even hear about dwarf planets, what else aren’t they teaching us?

8 Earth isn’t The Only Active Planet (tectonically)

One of the most important features to shape our planet, literally, is our ever-shifting tectonic plates. This process began about 3.3 to 3.5 billion years ago and gave rise to mountains, islands, volcanoes, sea vents, etc. It is one of a multitude of reasons life on Earth exists at all. The rest of our solar system seems pretty stagnant: we’ve got our rocky planets between the Sun and us and some big swirling gas giants behind us, big whoop.

Well, it wasn’t until 2016 that data from the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft revealed that innocuous little Mercury is shrinking, thanks to these same tectonic processes. Meaning, it hasn’t finished forming in the 4.6 billion years since the formation of our Solar System. Our little bubble of space as we know it today is merely a snapshot; don’t get too comfortable in the false assumption that everything will remain the same forever. If we just found out that Mercury was shrinking, imagine someday finding out the Earth is, too.

7 Walking On Air Isn’t All it’s Cracked Up To Be

Every kid dreams of becoming an astronaut. That is before the reality of adulthood crushes our dreams and forces us into a 9-5 office job to pay off student loans. But thanks to a beautiful duet between NASA and social media, we have a closer look into the lives of our fine spacemen and women more than ever before. And they’re happy to share. Some things like tears in space and floating through their cabins seem truly whimsical. However, the majority of adapting to zero gravity is difficult at best and debilitating at worst (especially returning to Earth after a long mission). This all brings us to their feet.

They’re not using them much. We know that much. Without the friction of walking, running, and other activities, the skin on the bottom of their feet softens and sloughs off. In order to conserve space for packing, they’ll wear the same socks multiple days in a row, too. And if they aren’t careful with removal, dead foot skin goes flying everywhere, creating macabre chaos of free-floating skin strips.

6 Space isn’t As Far Away As it May Seem

We’re not talking about how close we are technologically to commercial space travel. Instead, we’re talking about how little atmosphere there truly is between the Earth we walk on and where space begins, known as the Kármán Line. If you could get in your car and drive vertically at 60 mph, you would be in space in just an hour and change.

That’s right, that’s only 62 miles away from where you’re standing right now. Imagine that being your morning commute. The current record holder for highest space jump is Felix Baumgartner, sponsored by Red Bull (stellar marketing, honestly), and GoPro, who took a stratospheric balloon 24 miles high and jumped. The trip up only took him 90 minutes. And thanks to our good friend gravity, his free fall before deploying parachutes was only 3 minutes and 48 seconds.

5 Planet Nine

As romantic as gazing into the night sky is, real astronomy actually takes a lot of math (which is frightening enough on its own). Many discoveries are made by crunching the numbers, calculating away until an anomaly pops up, and scientists have to figure out why. At the outermost edge of our Solar System exists one such anomaly.

Astronomers Konstantin Batygin and Mike Brown from Caltech announced in 2015 the theoretical “Planet Nine” as an explanation for the movements of some objects in the Kuiper Belt cocooning our Solar System. Planet Nine was originally thought to be a Neptune-sized planet with an orbit around the Sun taking 15,000 earth years. In 2019 a new theory emerged: Planet Nine may actually be a primordial black hole. It is thought these phenomena formed at the beginning of the universe when extra dense pockets of material collapsed in on themselves. This one has possibly been captured by our Sun’s gravity and although it’s calculated to be quite tiny (only 3.5 inches across), it is still mighty. And even worse, mighty close.

4 There’s Nothing to Stop the Great Red Spot and other Space Storms

Anyone who has survived a major hurricane can attest to how truly powerful this kind of storm system can be. And yet, the worst ever seen on Earth is child’s play compared to the gas giant Jupiter’s Great Red Spot. Around two to three whole Earths can fit inside the storm, which has been documented by astronomers for over 300 years. Its winds blow up to 270 mph on average but around its oval-shaped edges can get up to 425 mph (keep in mind, the strongest winds detected on Earth have only been recorded over 200 mph a handful of times).

It also eats smaller vortices upon impact. In 2000, it engulfed three smaller storms and then, unbelievably, turned a deeper, bloodier red. Another example is Saturn’s raging six-sided storm nicknamed “the hexagon,” which has also been spinning for possibly hundreds of years. We don’t know why it has taken this shape or lasted this long. What we do know is that when travel between planets is available, we wouldn’t want to get anywhere near one of those!

3 Hell on Earth(‘s Neighbor)

Turns out, there’s little to actually love on Venus. We can’t think of what would be a worse death: being crushed by intense atmospheric pressure or incinerated by blazing temperatures. Good thing that with Venus we don’t have to decide. Both happen instantaneously upon entering Venus’s atmosphere. Temperatures average around 860 degrees Fahrenheit and it rains sulfuric acid.

What’s scary about this death planet is taking a good long look and seeing it as the potential warning it is: Venus got where it is thanks to a runaway greenhouse effect. Sound familiar? Venus may have been in habitable condition for around 3 billion years, until 700 to 750 million years ago. Problems like the polar caps melting on Earth seem like an easy fix compared to Venus’s seas having boiled away entirely.

2 The Solar System is Over the Hill

Life: you’re born, you grow, you age, and then you die. These are simple facts. The fleeting nature of our existence, some say, makes it beautiful. But we’re not the only ones with this blessing and curse. Our universe is theoretically 13.77 billion years old, plus or minus 40 million years. Scientists estimate that our Solar System is about 4.6 billion years old. And scientists think we’ve only got about another 5 billion years left in our little corner of space. That’s it.

To our knowledge, it’s taken this much time to develop intelligent life. Humans might not get a second chance at developing sentience should we die out. But should our descendants carry on so long, they better find a new home, because the end is near…

1 And When We Go, We’ll be Eaten by Our Own Sun

The Sun, benevolent light and energy giver, will be the deliverer of our demise. Once it runs out of the hydrogen necessary for nuclear fusion, its core will shrink, while conversely, it will begin to shed its outer layers, becoming a bloated carcass of its former self.

This growth will extend so far as to completely envelop our Earth. And before that, the heat and radiation cast off will roast everything on Earth entirely. It will even cremate everything in the entire Solar System. Only then will the Sun cool into a White Dwarf and cast light no longer. The once vibrant Solar System will become a cold, quiet, dead place. Like most everywhere in the universe.

Before we set out to explore the cosmos, we’d first have to know everything there is about our own neighborhood. And yet, other than the general position of things and a few specific details here and there, we know surprisingly little about what’s going on in our own solar system – especially in its most distant, darkest corners. 

10. The Moons of Mars

In the past few years, various missions to Mars have given us a fairly good idea of what the planet is like. Its moons, however, are a different story altogether. Phobos and Deimos are 17 and 9 miles in diameter, respectively, and are perhaps the weirdest moons in the Solar System. Their size and composition make them look more like asteroids than moons, though that’s really all we know about them.

We have no idea where either of them came from, though some scientists do believe that they’re disintegrated parts of a bigger moon that used to exist a few million years ago. Others maintain that based on their composition, Phobos and Deimos are closer to a class of asteroids found in the asteroid belt, suggesting that their origins lie outside the solar system. 

9. Venus

Venus is quite similar to Earth in some ways – like its size and mass – though in most other ways, it may as well be a different class of planet altogether. Its surface is perhaps one of the most hostile places for life in the Solar System, with temperatures reaching up to 900 degrees Fahrenheit. That’s hotter than Mercury, thanks to a severe greenhouse effect caused by its thick, choking atmosphere. 

It’s also one of the most mysterious planets in the Solar System, despite its close proximity to Earth. We don’t know why it spins in a counterclockwise direction – unlike any other planet except Neptune – or why the winds in its atmosphere blow at speeds of up to 220 miles per hour, or even what its surface really looks like. 

The most important mystery of Venus, though, is whether it harbors any kind of life. While its surface is definitely too extreme for any kind of life, Venus’s atmosphere could have the right, Earth-like conditions for rudimentary life forms. In fact, photographs of the planet taken back in 1927 do reveal dark, irregular patches in its atmosphere that absorb about the same amount of ultraviolet light as some bacteria and algae species on Earth.  

8. The Oort Cloud

The Oort cloud is a shell made up of icy objects at the very edge of our solar system – a region so far away from us that we have no equipment to even observe it. The Sun is too far for its light to reach here, and our only chance at photographing it – Voyager 2 – would take another 300 years to reach it. That begs the question: how do we know it even exists?

It all goes back to a Dutch astronomer in the 1950s – Jan Hendrik Oort – who was trying to understand long-period comets. While most comets return within a few hundred years, long-period comets take thousands of years to complete an orbit, and seem to come from arbitrary directions in the sky instead of the predictable orbits of short period comets.

His answer was the Oort cloud, which is now a widely accepted explanation for long-period comets. It’s a vast boundary of the Solar System made up of icy bodies of all shapes and sizes, though that’s really all we know about it. We don’t know how the Oort cloud was formed, how thick it is or what its bodies are made of, even if it’s easily the largest structure in the Solar System we know of.

7. The Kuiper Belt

Where long-period comets could be explained by the Oort cloud, short-period comets likely come from another major grouping of icy bodies in the Solar System: the Kuiper belt. Named after one of the most influential planetary scientists of all time – Gerard Kuiper – the Kuiper belt is perhaps the largest structure in the Solar System after the Oort cloud.

It’s also one of the most mysterious, as all Kuiper Belt Objects, or KBOs, lie in a distant region of the system, making its exploration impossible. Many of them are made up of materials right from the earliest days of the formation of the Solar System – some even have moons of their own!

The most enduring mystery of the Kuiper belt, however, is the range of colors we see whenever we photograph those objects. Till now, we’ve photographed about 1,000 KBOs, and all of them seem to emit a range of colors – from blues to whites to reds, even if they should ideally be a single pixel of color due to the distance. It could be a natural result of volcanoes, cosmic rays or a variety of other possible reasons, though it could also be signs of rudimentary forms of life, as organic matter tends to glow red in observations taken from afar. 

6. Saturn’s Hexagon Storm

Saturn has been a subject of interest for astronomers for millenia, mostly due to its fancy, unique rings – even if all of the outer planets also have rings of their own. Far more fascinating and mysterious, though, is its surface. Unlike Earth, Saturn is a gaseous planet made up almost entirely of hydrogen, along with some helium and trace amounts of other gasses like methane and ammonia. 

To say that Saturn’s surface is active would be an understatement, as it’s home to many diverse weather events that we’ve never been able to fully explain. By far the weirdest, though, is a hexagon-shaped storm located at its north pole. First discovered by the Voyager spacecraft in the early 1980s, it’s about as wide as two Earths, though that’s really all we know about it. We don’t know how it was formed – as we’ve never observed a non-circular, polygon-shaped storm anywhere else in the Solar System – or even how long it’s been active for. 

5. Oumuamua

Oumuamua – named after the Hawaiian word for ‘scout’ – was the first interstellar object we’ve ever observed in real time, though other than that, we know almost nothing about it. First spotted by University of Hawaii’s Pan-STARRS1 telescope back in 2017, the flying body was nothing like any other piece of rock we’ve ever come across.

For one, Oumuamua was about ten times as long as it was wide, which is unusual for other bodies we’ve seen flying about in space. It was also red in color, possibly from all the radiation it would have been exposed to over the eons. 

Its weirdest characteristic, however, was its speed – or more accurately its acceleration. Oumuamua was speeding up like it was propelled by an external force other than gravity, allowing it to enter and leave the Solar System instead of getting stuck orbiting the Sun. While comets have been observed to speed up near the sun due to its sheer gravity and heat, Oumuamua didn’t have a tail or any other feature of a comet, making that kind of natural acceleration impossible. 

4. The Coronal Heating Problem

The Coronal Heating Problem is one of the oldest unsolved mysteries in astrophysics: why is the Sun’s corona, or its atmosphere, so much hotter than its surface? We know that all of the Sun’s heat and energy comes from the powerful nuclear fusion reactions going on in its core, though they manage to heat up the surface by barely 10,000 degrees Fahrenheit. That’s a lot, though nowhere near enough to be the energy powerhouse of the Solar System that is our Sun. 

The heat is largely produced in its atmosphere, or the corona – the space where things start to get ionized into plasma due to the heat, as temperatures here can reach as high as two million degrees Fahrenheit. As you can guess, that shouldn’t happen; it’s like feeling warmer the farther away you get from a bonfire.

This transfer of heat from the Sun’s surface into its atmosphere has baffled scientists ever since it was first discovered in the 1940s. It’s not just one problem, either – we don’t know how that heat is transferred, how it’s sustained or even whether it’s a continuous event or multiple small explosions that look like a single event from afar. 

3. Uranus

When Voyager 2 flew past Uranus back in 1986, it reported nothing of note. It seemed to be a planet devoid of any character or special features – just one of the many icy bodies found in the distant reaches of the system, only much bigger. 

As we’ve found out in the years since then, though, Uranus may be the most fascinating and mysterious planet in the Solar System. For starters, its spinning axis is almost-completely perpendicular to its axis around the Sun, which means that it’s revolving sideways. We’re not sure why that is, though some scientists think that it’s a result of its collision with a large body during the early years of the Solar System. 

More curiously, Uranus’s atmosphere is unlike any other planet’s we’ve observed in the Solar System. In its lower, denser regions, temperatures can dip as low as -370 degrees Fahrenheit, which should ideally move up to about -100 Fahrenheit in the upper reaches. According to readings taken by the Voyager crafts in the 1980s, though, Uranus’s outermost atmosphere can get as hot as 1,300 degrees Fahrenheit.

This dramatic shift has perplexed astronomers and physicists ever since. Because of its distance, no part of Uranus should get even close to as hot as that, and it’s clear that it’s caused by something happening within its atmosphere. What that is, however, is anyone’s guess, as we’ve never observed such a weather phenomenon anywhere else in the Solar System.

2. Planet 9

The region beyond the orbit of Pluto until the boundary of the Oort cloud is sparsely-lit and mind-bogglingly vast, making it impossible for even our best equipment to scout it. That begs the question: are there other large bodies – possibly even planets – hiding in the darkness that we’ve just never seen?

If a study from 2016 published in The Astronomy Journal is to be believed, the answer is a definitive ‘yes’. Researchers studied various known Kuiper belt objects and found that six of them were going around the Sun in weird, abnormal orbits. The distortion was towards the same side in all six cases, too, which suggests that they’re being pulled by the same large object. 

According to their calculations, this body is about ten times larger than Earth, even if we’ve never directly photographed or even observed it. Since then, we’ve found at least thirteen more Kuiper belt objects with similarly-distorted orbits.

1. The Moon

The moon is our nearest and most familiar neighbor in this vast, cold expanse called space, though till now, we have no clue about where it came from. Scientists just can’t agree on a single unified theory on the true origins of the moon, and it seems that every new study on the topic raises more questions than it answers. 

The prevailing theory is known as the Giant Impact Hypothesis, which states that the moon was formed as a result of a collision between a young Earth and a Mars-sized planet called Theia. The debris from the collision came together over millions of years to give birth to the moon, which could explain its unusually large size. 

If that were true, though, the moon would be completely made out of material from Theia. Samples brought from the various Apollo missions directly contradict that, however, as the moon has since been found to be almost identical in composition to Earth, especially its mantle. While it rules out the giant-impact theory, it does seem to suggest the moon and Earth formed in the same region of the Solar system, likely during its early, tumultuous years.