Buzz
Our solar system is made up of a central star, eight planets, several dwarf planets, and numerous comets and asteroids. Centuries ago, people believed there were more than just eight planets. They mistakenly classified asteroids as planets, discovered imaginary ones, and speculated about other possible planets.
Some of these speculations proved to be true—such as the discovery of Neptune, which followed predictions of its existence. However, many other predictions have remained just ideas. While we think some of these planets might be real, others are likely not. Still, it’s always worth hoping.
10. Vulcan
Vulcan is a theoretical planet believed to exist between Mercury and the Sun. This idea was proposed centuries ago when astronomers noticed slight changes in Mercury's orbit with each revolution around the Sun.
In 1859, French astronomer Urbain-Jean-Joseph Le Verrier theorized that these changes were due to the gravitational pull of an undiscovered planet between Mercury and the Sun. He named it Vulcan, after the Roman god of blacksmithing. Le Verrier suggested that the planet could not be seen because it was too close to the Sun.
The following year, amateur astronomer Edmond Modeste Lescarbault reported observing a small dark spot near the Sun. Le Verrier identified this dot as the planet Vulcan. Other astronomers later claimed to have seen the planet, though some argued that they couldn’t detect it.
Vulcan quickly gained recognition as the first planet of the solar system, despite the lack of solid evidence. This was likely because of Le Verrier's reputation in astronomy. Thirteen years earlier, he had predicted Neptune's existence after observing that an unknown planet was altering Uranus' orbit. Moreover, Vulcan's existence seemed to be the only plausible explanation for Mercury's irregular orbit.
This belief was overturned in 1915 when Albert Einstein’s Theory of General Relativity disproved the existence of Vulcan. Einstein explained that large objects like the Sun could warp both time and space. Mercury’s orbital changes were the result of traveling through a “distorted space-time” created by its proximity to the Sun.
9. Tyche
Tyche is a speculative planet believed to reside in the Oort cloud, located at the outer edge of our solar system. It was first proposed in 1999 by a team of astrophysicists from the University of Louisiana. They theorized that Tyche is comparable in size to Jupiter, has three times Jupiter's mass, and takes 1.8 million years to complete one orbit around the Sun.
The astrophysicists introduced the concept of Tyche to explain the origin of long-period comets, which take over 200 years to complete a single orbit. Previously, astronomers believed that these comets originated from random locations across the solar system.
However, the scientists suggested that these comets are actually ejected from the Oort cloud and are propelled toward the Sun by Tyche's gravitational influence. NASA conducted a search for Tyche using its Wide-field Infrared Survey Explorer (WISE) telescope between 2012 and 2014, but no evidence of the planet was found.
8. Planet V
Around 3.8 billion years ago, a shower of asteroids bombarded the surfaces of Mercury, Venus, Earth, Mars, and the Moon. This event is known as the Late Heavy Bombardment (LHB). However, the exact origin of these asteroids remains a mystery.
Some scientists believe that these asteroids could have originated from the remains of a planet called Planet V, which once existed between Mars and the asteroid belt separating Jupiter from Mars today.
The theory suggests that Planet V was smaller than Mars, and its orbit was heavily influenced by the gravitational forces of Jupiter and other outer planets. Eventually, Planet V became unstable, drifting into the asteroid belt and causing asteroids to be ejected toward Mars and the inner planets. The planet itself was likely either pulled into the Sun or ejected far from the solar system.
An alternative theory suggests that Planet V might have simply avoided the asteroid belt and instead collided with another planet. Some astronomers propose that it crashed into Mars, creating the vast Borealis Basin, which covers 40 percent of the Martian surface. If this were the case, the asteroids that impacted the inner planets could have been fragments thrown into space during the collision.
Other scientists argue that the hypothetical Planet V never existed. They believe the Late Heavy Bombardment (LHB) was triggered by the orbital shifts of Jupiter and Saturn, which flung asteroids from the asteroid belt toward the inner planets. There is also a theory suggesting that Mars’ gravitational pull might have shattered a large asteroid, causing the LHB.
7. Theia
It was once believed by scientists that the Earth and Moon formed after a planet named Theia collided with a young Earth. The impact caused Theia to disintegrate, with fragments from the planet scattered into space. One of these fragments eventually became the Moon.
This theory was debunked after analysis of Moon rocks revealed that the Earth and Moon share the same material. Today, scientists believe that Theia collided with an older Earth around 4.5 billion years ago. Both planets merged to form Earth, and a fragment of Earth later broke off to become the Moon.
6. Phaeton
For a long time, astronomers believed there was an undiscovered planet between Mars and Jupiter. This idea gained traction after Giuseppe Piazzi discovered what was thought to be the planet Ceres in 1801. A year later, Heinrich Olbers discovered what appeared to be planet Pallas.
Olbers later realized that Ceres and Pallas had once been part of the same planet. This hypothesis gained more support with the discovery of the planets Juno and Vesta. Eventually, Ceres, Pallas, Juno, and Vesta were reclassified as asteroids and considered the remnants of a hypothetical planet known as Phaeton.
In earlier times, astronomers believed that Phaeton had disintegrated, creating not only the four large asteroids but also all the others in the asteroid belt between Mars and Jupiter.
Some astronomers speculated that Phaeton had exploded, been destroyed by Jupiter, or collided with another celestial object. Some suggested that this object could be Nemesis, a hypothetical star once thought to be part of our solar system.
However, modern astronomers have refuted the idea of Phaeton's existence. They argue that the asteroids in the asteroid belt have always been there, unable to form into a planet due to Jupiter's immense gravitational pull keeping them scattered between Mars and Jupiter.
5. Nibiru
Nibiru is a theoretical planet said to be hiding somewhere in our solar system. While NASA denies its existence, conspiracy theorists have long claimed it was real and predicted it would collide with Earth in 2012.
It is important to note that Nibiru is also known as Planet X, but this should not be confused with the hypothetical Planet Nine, which is also referred to as Planet X. We will discuss Planet Nine shortly.
The idea of Nibiru was introduced by Zecharia Sitchin in his 1976 book, The Twelfth Planet, where he argued that the planet orbited the Sun once every 3,600 years. Many years later, a self-proclaimed psychic named Nancy Lieder claimed that aliens had warned her Nibiru would collide with Earth in 2003, later changing the predicted year to 2012.
In 2011, Comet Elenin passed by Earth and broke apart after getting too close to the Sun. Some staunch believers claimed this comet was Nibiru on its way to impact Earth. Since we’re still here reading this, it’s safe to assume that Nibiru likely doesn’t exist — or it simply missed Earth and will return in 3,600 years.
4. Planet Nine
Planet Nine is another theoretical planet that might be hidden in our solar system. While Nibiru is largely dismissed, NASA and astronomers at the California Institute of Technology believe Planet Nine could exist, though no definitive proof has been found. The speculation arose from studying the odd orbits of several objects located far beyond Neptune.
Experts believe that Planet Nine could be roughly the same size as Uranus or Neptune, with a mass about 10 times that of Earth, and it would be located 20 times farther from the Sun than Neptune. They think it takes between 10,000 and 20,000 years to complete a single orbit around the Sun.
3. Tiamat
The Sumerians believed a planet named Tiamat once existed between Mars and Jupiter. However, there is ongoing debate about its current location. Tom van Flandern argued in his book, Dark Matter, Missing Planets and New Comets, that Tiamat was destroyed 65 million years ago and became the asteroid belt.
Zecharia Sitchin challenged this theory in his books The Twelfth Planet and The Cosmic Code. He suggested instead that Tiamat had altered its orbit and became Earth. According to Sitchin, the planet shifted after colliding with a hypothetical planet named Marduk, along with its three moons.
Sitchin proposed that this collision created a new planet that eventually broke into two parts. One half moved closer to the Sun, forming Earth and the Moon, while the remaining debris became the asteroid belt. He also claimed that Tiamat's moons were thrown into new orbits, with one of them crashing into Mars and forming the planet's great rift.
2. An Unnamed Planet
Planets are often unstable shortly after their formation. Their orbits tend to shift frequently due to the constant gravitational influence of nearby planets. In 2005, three research teams proposed the Nice Model to explain the formation of our solar system based on this concept.
Historically, the gravitational forces of other planets caused Uranus and Neptune to swap orbits, while also pushing Jupiter and Saturn farther from the Sun. Jupiter is also thought to have briefly moved closer to the Sun before returning to the outer regions of the solar system.
The Nice Model was widely accepted until 2011, when some scientists argued that for the model to be valid, there must have been a fifth planet between Mars and Jupiter. These scientists suggested that this planet was likely ejected from the solar system by the gravitational forces of either Saturn or Jupiter.
In 2015, another group of scientists refuted the Nice Model, as it failed to account for the formation of the inner planets (Mercury, Venus, Earth, and Mars). They explained that Jupiter would have cleared out the inner planets, especially Mercury and Mars, had it ever ventured into the inner solar system.
Had the Nice Model been correct, the four inner planets would have formed much later than the outer planets, or they could be the remnants of a planetary cataclysm caused by Jupiter. This theory suggests that other inner planets were sent farther into the solar system, along with one or two planets from the outer system.
1. Counter-Earth
In the 4th century BC, the Greek philosopher Philolaus proposed the idea of a planet he called Counter-Earth. According to him, Counter-Earth always resided on the opposite side of the solar system, maintaining a position such that the Sun, Earth, and Counter-Earth were always aligned in a straight line.
Philolaus suggested that Counter-Earth was invisible to us on Earth, hidden by the Sun. Today, we understand that such a planet could never have existed, as its gravitational interactions with other planets would have made it detectable from Earth.
The gravitational effects of Mercury and Venus would have caused Counter-Earth’s orbit to shift, pushing it from its hypothetical position on the opposite side of the solar system. Over time, this would have brought it into view from Earth, and both planets would have eventually collided as they drew closer together.
If Earth and Counter-Earth had collided, they would have either formed a new Earth or missed each other entirely. In the case of a near miss, their massive gravitational forces would have been so strong that they would have been forced into entirely new orbits.
