Following the discovery of Neptune in 1846, many astronomers began speculating that there may be another planet beyond Neptune's orbit, at the beginning of the 20th century, Astronomer Peroival Lowell proposed the Planet X hypothesis to explain apparent discrepancies in the orbits of the ice giants, speculating that the gravity of a large unseen ninth planet could have perturbed Uranus enough to account for the irregularities. However, there have also been many other hypothetical planets proposed to exist beyond Neptune, most of them however have been disproven.
Brahma and Vishnu[]
Main Articles: Brahma and Vishnu
In 1911, Indian astronomer Venkatesh P. Ketakar proposed the existence of two hypothetical planets beyond Neptune, which he named Brahma and Vishnu. Ketakar suggested that these planets were responsible for perturbing the orbits of many periodic comets, indicating their presence in the outer reaches of our solar system. He estimated that Vishnu would be located at a semi-major axis of approximately 59.573 astronomical units (AU) from the Sun, with an orbital period of about 458.27 years. However, no evidence has been found to support the existence of these planets, and they are now considered disproven.[1]
Oceanus[]
Main Article: Oceanus
Oceanus is a hypothetical planet proposed by American astronomer Thomas J.J. See in the early 20th century. See suggested the existence of three planets beyond Neptune, with Oceanus being the nearest at approximately 41.25 astronomical units (AU) from the Sun, corresponding to an orbital period of about 272 years.[2] The other two proposed planets, referred to as "trans-Oceanus" planets, were theorized to orbit at 56 AU and 72 AU, with periods of 420 and 610 years, respectively.[2] These propositions aimed to explain certain irregularities observed in the orbits of known outer planets. However, subsequent astronomical observations and analyses have not provided empirical evidence supporting the existence of Oceanus or the additional trans-Neptunian planets proposed by See.[3]
Hades[]
Main Article: Hades
In 1902, German astronomer Theodor Grigull proposed the existence of a hypothetical planet named Hades to account for observed irregularities in the orbits of known planets, particularly Uranus. Grigull suggested that Hades was a Uranus-sized planet located approximately 50 astronomical units (AU) from the Sun, with an orbital period of about 360 years.[4] He based his hypothesis on the analysis of cometary orbits extending beyond Neptune. In 1921, Grigull revised his estimates, proposing that Hades had an orbital period between 310 and 330 years and was situated fifty times farther from the Sun than Earth.[5] Despite these predictions, extensive searches have failed to detect such a planet, and its existence remains unconfirmed. The concept of Hades has largely been set aside in favor of more recent hypotheses, such as Planet Nine.
Planet Nine[]
Main Article: Planet Nine
Planet Nine is a hypothesized planet in our solar system, proposed to explain the unusual clustering of orbits observed in certain distant Kuiper Belt objects (KBOs). In 2016, Caltech researchers Konstantin Batygin and Mike Brown suggested that this unseen planet could be influencing these KBOs through its gravitational pull.[6]
The proposed characteristics of Planet Nine include a mass approximately 6.2 times that of Earth, a semimajor axis around 380 astronomical units (AU), and an orbital inclination of about 16 degrees. Its orbit is highly elongated, with a perihelion (closest approach to the Sun) near 300 AU.[7]
Recent studies have strengthened the case for Planet Nine's existence. For instance, a 2024 study analyzed the orbits of trans-Neptunian objects (TNOs) and found that their distribution aligns closely with predictions made by the Planet Nine hypothesis. The study concluded that the observed orbital architecture of these TNOs is statistically consistent with the presence of Planet Nine.[8]
Planet Ten[]
Main Article: Planet Ten
Planet Ten is a potential planetary-mass object in the outer Solar System, likely located within the Kuiper Belt. Researchers from the University of Arizona's Lunar and Planetary Laboratory (LPL) suggest that an unseen object, possibly the size of Mars or Earth, could explain the unusual orbital tilts of distant Kuiper Belt objects (KBOs). These KBOs' orbits seem to be influenced by a gravitational anomaly, indicating the presence of a hidden, massive object. The object is believed to be closer than the proposed Planet Nine, which resides far beyond Pluto.[9]
Planet X[]
"Planet X" redirects here. For the conspiracy theory, see Nibiru cataclysm. For the hypothetical planet first proposed in 2014, see Planet Nine.
Planet X, first proposed in 1906 by the American astronomer Percival Lowell, was a hypothetical ninth planet believed to exist beyond Neptune.[10] Lowell's calculations suggested that irregularities in the orbits of Uranus and Neptune could be explained by the gravitational influence of an unseen massive object.[11] He began an extensive search for the planet, which he termed "Planet X," and this effort continued after his death in 1916.[12] In 1930, Clyde Tombaugh discovered Pluto, which was initially thought to be the Planet X Lowell predicted.[13] However, Pluto's small size and mass later proved insufficient to account for the observed orbital discrepancies, leading to doubts about the existence of Lowell's Planet X.[14] Subsequent research attributed the orbital irregularities to measurement errors rather than the presence of a large, distant planet.[15]
Pickering's Planets[]
Main Article: Pickering's Planets
William Henry Pickering, an American astronomer, proposed the existence of several hypothetical planets beyond Neptune between 1909 and 1938. He suggested that these planets, named O, P, Q, R, S, T, and U, could explain observed anomalies in the orbits of Uranus and Neptune. Pickering's predictions included specific orbital parameters for these planets, such as semi-major axes, eccentricities, orbital periods, and inclinations. For instance, he estimated that Planet O would have a semi-major axis of 51.9 AU and an orbital period of 373.5 years. However, despite extensive searches, none of these hypothetical planets were ever detected, and their existence remains unconfirmed.[16]
Tyche[]
Main Article: Tyche (hypothetical planet)
Tyche was a hypothetical gas giant proposed to exist in the outer reaches of our Solar System, specifically within the Oort cloud—a vast, spherical shell of icy bodies extending from approximately 2,000 to 100,000 astronomical units (AU) from the Sun. First suggested in 1999 by astrophysicists John Matese, Patrick Whitman, and Daniel Whitmire, Tyche was theorized to be a massive planet, potentially up to four times the mass of Jupiter, with an orbital period of about 1.8 million years. This proposed orbit would place Tyche at a distance of approximately 15,000 AU from the Sun, well within the Oort cloud's boundaries. The hypothesis was based on observed clustering in the orbits of long-period comets, which the researchers speculated could be influenced by the gravitational presence of such a distant planet. However, in 2014, NASA's Wide-field Infrared Survey Explorer (WISE) mission conducted an extensive survey of the sky and found no evidence of an object matching Tyche's proposed characteristics. This led to the conclusion that Tyche, as originally hypothesized, does not exist.[17]
References[]
- ↑ https://www.forbes.com/sites/kionasmith/2018/06/08/our-obsession-with-hidden-planets-didnt-start-with-planet-nine/
- ↑ 2.0 2.1 https://solarviews.com/eng/hypothet.htm?
- ↑ https://en.wikipedia.org/wiki/Planets_beyond_Neptune
- ↑ https://solarviews.com/eng/hypothet.htm
- ↑ https://sciencephotogallery.com/featured/artwork-of-the-hypothetical-planet-hades-science-photo-library.html
- ↑ https://www.caltech.edu/about/news/caltech-researchers-find-evidence-real-ninth-planet-49523?utm
- ↑ https://arxiv.org/abs/2108.09868?utm
- ↑ https://arxiv.org/abs/2404.11594?utm
- ↑ https://www.space.com/37295-possible-planet-10.html
- ↑ https://science.nasa.gov/solar-system/planet-x/#:~:text=The%20%E2%80%9CX%E2%80%9D%20is%20the%20letter,discovery%20of%20Pluto%2C%20in%201930.
- ↑ https://www.bbc.com/future/article/20210216-the-massive-planet-scientists-cant-find#:~:text=A%20false%20trail,considered%20the%20elusive%20planet%20X.&text=Alas%2C%20it%20was%20not%20to,was%20laid%20for%20its%20resurrection.
- ↑ https://www.planetary.org/articles/is-planet-x-planet-nine-real#:~:text=The%20story%20behind%20Planet%20X,to%20discover%20Pluto%20in%201930.&text=As%20our%20understanding%20of%20Pluto,planets%20themselves%20well%20enough%20initially.
- ↑ https://www.astronomy.com/science/percival-lowells-three-early-searches-for-planet-x/#:~:text=On%20February%2018%2C%201930%2C%20he,to%20be%20in%20the%20area.
- ↑ https://www.skyatnightmagazine.com/space-science/percival-lowell#:~:text=Collector/Getty%20Images-,Pluto,Earth%20and%20therefore%20quite%20bright.
- ↑ https://www.smithsonianmag.com/smart-news/bizarre-beliefs-astronomer-percival-lowell-180962432/#:~:text=Although%20Pluto%20was%20eventually%20observed,seeing%20inside%20his%20own%20eye.
- ↑ https://www.lindahall.org/about/news/scientist-of-the-day/william-henry-pickering/#:~:text=Pickering%20then%20turned%20his%20attention,S%2C%20T%2C%20and%20U.
- ↑ https://en.wikipedia.org/wiki/Tyche_(hypothetical_planet)