You might think we know solar system very well, but there is much more to our cosmic neighborhood than meets the eye (or the telescope).
Most of the good stuff, like planets, the moons and the asteroid belt, are grouped relatively closely toward the center of the solar system and are illuminated by the sun’s glare, making them somewhat easy to spot. But if you look straight the edge of the solar system, you will find a vast and dark place in which mysterious entities can easily hide. As a result, researchers have had a field day thinking about all the things that could be hiding there.
From a massive ninth planet and a second Kuiper Belt to interstellar visitors and mini-black holes, here are eight hypothetical objects that could be lurking in the dark.
Connected: 10 out-of-this-world solar system discoveries made in 2023
Planet Nine
The largest and most controversial object that may be lurking in our cosmic neighborhood is a hypothetical ninth planet that resides far beyond the other known worlds of the solar system, which researchers have creatively dubbed “Planet Nine.”
Scientists first proposed Planet Nine in 2016 to explain the strange orbits of several large objects in and around the Kuiper Belt – a massive ring of asteroids and other rocky objects that surround the sun beyond the orbit of Neptune. Some researchers believe these objects are being gravitationally pulled by a massive, unknown world beyond the Kuiper Belt. However, despite finding even more of these objects in recent years, the actual planet has eluded detection – until now.
If it exists, Planet Nine is likely to be an icy gas giant about seven times more massive than Earth, which would make it the fifth largest planet in the solar system. However, the planet could be extremely far away, perhaps orbiting our sun once every 10,000 years, meaning it would be very faint and extremely difficult to spot.
Researchers have narrowed down the area where Planet Nine may be hiding, but are limited by the power of currently available telescopes. However, with new, more advanced telescopes coming online soon, it could be discovered within the next few years, experts recently told Live Science.
Black holes for kids
Not everyone believes that Planet Nine is responsible for the orbital anomalies of Kuiper Belt objects. Other scientists believe that something equally difficult to detect may be pulling on these distant space rocks – a mini black hole.
Researchers argue that a black hole that is about the size of a moon or planet could exert the same gravitational force as the supposed Planet Nine. Black holes of this size are theoretically possible, but have never been observed, which makes the idea somewhat controversial. To prove this theory, researchers would probably need to detect Hawking radiation coming from the black hole or look at something falling beyond its event horizon.
But even if a baby black hole doesn’t masquerade as Planet Nine, other researchers believe there may be even smaller “primordial” black holes in the outer solar system, and that these super-small singularities it can cause some planets and moons to wobble.
Captured alien worlds
Some researchers believe there may be more hidden worlds besides Planet Nine in the outer reaches of the solar system.
But unlike Planet Nine, these hypothetical planets – known as rogue planets – may not have originated in our neck of the woods. Instead, they would be missed by distant stars that may have been pulled by the sun after drifting through interstellar space for eons.
Scientists have hundreds of rogue planets have already been discovered zooming in on the Milky Way. However, in 2023 researchers proposed that a rogue planet may be hiding near the edge of the solar system, even further than Planet Nine. And if that wasn’t crazy enough, a letter from 2024 also suggested it there’s room for up to five rogue Earth-sized planets towards the edge of our cosmic neighborhood.
The second Kuiper generation
The Kuiper belt could play a key role in discovering hidden worlds within the solar system. But it may also be hiding a secret of its own – a twin.
In 2023, researchers announced the possible discovery of a dozen new rock objects that lurk beyond the Kuiper Belt. These large space rocks, which are likely all asteroids, are located about 10 AU (10 times the distance between Earth and the Sun) from the bulk of the Kuiper Belt – suggesting they may belong to a second, smaller generation of asteroids. .
However, other surveys have failed to identify more of these extra Kuiper Belt objects, leaving the theory in limbo for now.
More dwarf planets
After missing whole worlds and asteroid belts, the next largest objects that could be hiding right under our noses are dwarf planets – large space rocks that are large enough to be gravitationally rounded, like planets, but not quite so. large enough to completely clear their orbital path. the garbage.
The solar system hosts five known dwarf planets: Ceres, Haumea, Eris, Makemake, and the former planet Plutoaccording to NASA. Other candidates such as Gonggong, Quaoar and Sedna are not officially known as dwarf planets, but are often called such by astronomers.
All of these mini-worlds lie within the Kuiper Belt or beyond – except for Ceres, which is in the asteroid belt between Mars and Jupiter. But as we’ve already seen, there are many places where objects can be hidden in the outer solar system. Some estimates suggest there may be dozens or even as many as a hundred dwarf planets still waiting to be discovered, according to International Astronomical Union.
Until recently, researchers believed that the dwarf planets were mostly geologically dead, with the exception of Pluto, which there is an icy supervolcano. However, new data collected by the James Webb Space Telescope revealed this Eris and Makemake may also be geologically activewhich increases the chances that they or other future dwarf planets could harbor alien life.
Volcanic comets
Far beyond the Kuiper Belt lies a giant reservoir of comets known as the Oort Cloud, which lies about 1,000 AU from the sun. A very small percentage of these icy objects are what researchers refer to as cryovolcanoes, or cold volcanoes, that spew frozen dust and gas into space when they erupt.
Cryovolcanic comets only explode near the sun, when solar radiation causes intense pressure to build up within their outer shells, or cores, eventually causing explosive explosions. However, most comets have highly elliptical orbits, meaning they spend most of their orbits floating in the outer solar system before entering the inner solar system every few decades or centuries. This makes it difficult to tell which ones are cryovolcanic.
For example, Comet 12P/Pons-Brooks, also known as “infernal comet“, made the closest approach to the sun in about 71 years when he slingshot around our house star in April 2024. Since June 2023, when the comet began its dive bomb into the inner solar system, the comet has been it is distinguished by exploding several times. But for the previous 69 years, astronomers did not see it explode once.
As a result, astronomers suspect that many more cryovolcanic comets are hiding in plain sight within the Oort cloud, and that we will only identify them when they eventually approach the sun.
Interstellar visitors
In addition to suspected rogue planets, the sun’s gravitational pull is also capable of attracting other free-floating objects from interstellar space. However, unlike the supposed captured worlds, most of these objects are likely to pass through our cosmic neighborhood and never return.
Astronomers have already seen two confirmed interstellar objects: ‘Oumuamua, an elongated object that made headlines in 2017 after some researchers wrongly suggested it might be an alien probe; AND Comet 2I/Borisov, which was seen in 2019 as it cruised through the solar system. Other researchers suspect that a The small meteor that exploded over Earth in 2014 it was also an interstellar interstellar.
Given the small number of confirmed sightings, you’d be forgiven for thinking that interstellar objects are rare. However, some researchers estimate that there are between 1,000 and 10,000 of these objects in the solar system at any given time, according to sister site Live Science. Space.com.
Some researchers have proposed the creation of a special “interstellar interceptor” spacecraft. that can be hidden in orbit around Earth so that scientists can quickly track and study new objects as soon as they are discovered. But at the moment, there are no official plans for such a spacecraft.
Killer asteroids
The final objects on this list are the most dangerous. But thankfully, they are among the least likely to be found.
The inner solar system is filled with potentially dangerous asteroids, which orbit the sun close enough to Earth to be considered a threat to our planet (although most will never approach us). These dangerous space rocks can range in size from “the city killers“that could wipe out major population centers in”planet killers“as the one who wiped out the dinosaurs.
Similar massive rocks reside in the Kuiper Belt and beyond. However, unlike comets, asteroids don’t usually migrate in and out of the inner solar system, meaning these rocks don’t pose much of a threat to us. But that doesn’t mean it’s impossible. If a massive asteroid were headed for Earth, it could too to be darkened by the brightness of the sundepending on its position, which can give us very little warning before it grabs us.
Scientists consider potentially dangerous asteroids pose no threat to Earth for at least 1000 years. However, this calculation is only based on the space rocks we know about.