Planet Nine
Planet Nine is a hypothesized planet proposed to exist in the far reaches of the solar system, beyond the Kuiper Belt, which is a region filled with icy debris located past Neptune. First suggested by scientists from the California Institute of Technology in 2016, the existence of Planet Nine is inferred from mathematical modeling and computer simulations that analyze the unusual orbits of several trans-Neptunian objects, indicating they may be influenced by a substantial gravitational force from a larger yet unseen mass. Estimated to be around ten times more massive than Earth, Planet Nine is believed to have an elliptical orbit that could range from approximately 250 astronomical units (AU) at its closest to 600-1,200 AU at its farthest point from the sun, taking between 10,000 to 20,000 years to complete one orbit.
The gravitational effects observed in objects like Sedna, which exhibit peculiar orbital patterns, led researchers Mike Brown and Konstantin Batygin to suggest that a true planet, such as Planet Nine, could be responsible for these anomalies. While the planet has not been directly observed, confirmation of its existence would significantly alter our understanding of the solar system's structure. Some theories propose that Planet Nine could have originally been an exoplanet captured by the sun's gravity billions of years ago, potentially making it the first known exoplanet within our solar system. As of now, the existence of Planet Nine remains a hypothesis, and astronomers continue to seek direct evidence to validate its presence.
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Planet Nine
In January 2016 scientists from the California Institute of Technology (Caltech) published a paper in which they presented evidence suggesting the existence of a ninth planet at the far reaches of the solar system. The hypothetical "Planet Nine" has not yet been seen, but its existence has been surmised through mathematical modeling and computer simulations based on the irregular orbits of several objects in the Kuiper Belt. The orbits of those objects aligned in a way that implies there is gravitational influence from a much larger mass. Scientists have suggested that direct observation of Planet Nine could occur by 2021.
Overview
Planet Nine is situated beyond the Kuiper Belt, an icy debris field located past the orbit of Neptune. While Neptune is located about 30 astronomical units (AU) from the sun and takes nearly 165 years to complete its orbit, Planet Nine is thought to have an elliptical orbit that is about 250 AUs from the sun at its closest approach (perihelion) and 600 to 1,200 AUs at its aphelion. Its vast distance from the sun means Planet Nine would take 10,000 to 20,000 years to complete one orbit. Planet Nine is estimated to be ten times more massive than Earth. The remote position of Planet Nine explains why it has not yet been detected by conventional astronomical equipment.
The evidence suggesting the existence of Planet Nine was put forth by planetary scientists at Caltech. Mike Brown and Konstantin Batygin analyzed the orbits of Sedna and five other extreme trans-Neptunian objects and suggested the gravitational effects of a planet was causing their unusual orbital patterns, which swing out in one direction and overlap at their perihelions. Since that circumstance is extremely unlikely to occur at random, the scientists conducted various modeling scenarios and determined that an object that would qualify as a true planet based on its mass could be influencing the orbits of the six other trans-Neptunian objects.
Confirmation of Planet Nine’s existence would reshape current models of the solar system for the second time in just over a decade. In 2006 the original ninth planet, Pluto, was demoted from the status of a true planet to that of dwarf planet when the International Astronomical Union redefined the qualifying criteria for planets. Brown’s discovery of the dwarf planet Eris was the impetus behind Pluto’s demotion and the new criteria for planets.
Some scientists have suggested that Planet Nine could have been pulled into the solar system by the sun billions of years ago and that it could be an exoplanet, an object that orbits a star outside the solar system. If that were the case, Planet Nine would be the first exoplanet to be discovered within the solar system. At this point, however, the existence of Planet Nine is still just a hypothesis. If Planet Nine exists, direct observation of it will be difficult due to its great distance, dimness, and its unknown orbit. Nevertheless, Brown and Batygin published the evidence for the existence of Planet Nine in the hopes that it would spur others in the scientific community to attempt to directly detect the hypothesized planet.
Bibliography
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