Planet X, also called New Planet, is a hypothetical planet that orbits the sun in the outermost regions of the solar system. So far, there are eight known planets in the solar system, but there may be more planets. Planets are weak and small, so detecting planets that are far away is extremely difficult. The existence of a ninth planet was proposed in response to observations of distant objects called extreme transneptunian objects (ETNOs). While observing an ETHNO cluster, astronomers noticed that its orbits are slightly inclined in such a way that it suggests that there is a massive object in the outer solar system. Astronomers have calculated that the mass of this object is between five and ten Earth masses, making it a planet. Although there is some indirect evidence for the existence of the New Planet, astronomers have not yet found any concrete evidence that it exists. This means that very little is known about the New Planet, and so far only astronomers have been able to predict its orbit, size and mass. If the New Planet exists, it will probably be a super-Earth or a mini-Neptune.
Orbit
The orbits of the planets in our solar system, including Neptune, the farthest from our Sun.
If the new planet existed, it would orbit the sun at an extremely large distance. The new planet is estimated to orbit the sun at a maximum distance of 75 billion miles (120 billion kilometers), or about 26 times farther from the sun than Neptune. The planet would need nine more than 20,000 Earth years to complete an orbit at such a great distance from the sun.
Formation
The gas giants of our solar system
There are two possibilities for how the New Planet might have formed and ended so far from the sun. The New Planet is unlikely to have formed at its estimated distance from the sun, so it probably originated in the same region of the solar system as the gas giants. If the new planet were formed closer to the sun, the gravitational pull of Jupiter and Saturn would probably have launched the new planet into the outermost regions of the solar system. Another possibility is that the New Planet never formed in our solar system, but may be a captured planet that formed around another star. While this may sound strange, it is possible. The new planet could have formed in another solar system and was ejected during the formation of its solar system, traversing space until it fell into orbit around the sun. Another possibility is that our solar system has passed close enough to another solar system for the new planet to be stolen by the sun.
Looking for the new planet
At the moment, the only evidence of the New Planet is the inclined orbits of the ETNOs. Unfortunately, this evidence is not enough to confirm the existence of the New Planet. More direct evidence will need to be found for the New Planet to be accepted as real. Preferably, these tests will come in photographs taken with telescopes. Unfortunately, every search for the New Planet has been left empty, but that does not necessarily mean that the New Planet does not exist. The new planet could be so far away and faint that telescopes will barely be able to detect it, and more advanced technology may be needed. Astronomers will need to continue examining the sky in areas where the New Planet is expected to be. If the New Planet exists, it will probably be in the near future.
Planet Nine fact sheet
Radius Two to four times larger than Earth
missa
Five to ten times the Earth
Distance from the sun
75 billion miles (120 billion kilometers)
Length of the year
20,000 Earth years
Aidan Remple June 7, 2022 in Science