Does Planet Nine or Planet X exist?

"The hypothetical Planet Nine is imagined as an ice giant in this artist’s conception. Neptune’s orbit is shown as the ellipse around the distant Sun (upper right). Credit: ESO/Tom Ruen/nagualdesign" (Astronomy, Does Planet Nine exist?)

The terms "Planet 9" and "Planet X" mean the strange gravity effect in the Kuiper Belt. That effect causes anomalies in Neptune and Uranus trajectories and it affects also some Kuiper Belt objects. Nobody has seen Planet 9 yet. The interesting thing is how that large object can remain unseen. 

There is a possibility that energy travels to that planet's nucleus which can be colder than its shell. That increases its mass all the time, especially in cases where energy cannot travel out from that planet's shell. 

Researchers predict that the temperature on the planet is about 47 Kelvin. That means -226 degrees Celsius and the absolute zero point is -273,15 C or 0 K. At that point atom movement ends and there is no infrared radiation from that object. 

"The newcomer replacing Pluto presently goes by “Planet Nine.” If and when it finally shows up, it will get the honor of a real name, but so far, the evidence for this hypothetical planet is all indirect. Just as many of the thousands of known planets orbiting other stars have been found by observing their gravitational effects, rather than by actually seeing them, Planet Nine has been identified thanks to the way it has apparently been tugging on a variety of small bodies in the outer solar system and pulling their orbits into lockstep patterns. If it exists, Planet Nine orbits the Sun at an average distance around 550 astronomical units (AU), or 550 times as far as Earth is from the Sun. Astronomers also think it has between five and 10 times Earth’s mass." (Astronomy, Does Planet Nine exist?)

"The orbits of 96 of 109 distant minor planets and extreme trans-Neptunian objects (ETNOs), known as of January 2021, are diagrammed here. The farthest point from the Sun of each is greater than 200 times the distance between Earth and the Sun (1 AU). Orbits colored red are ETNOs aligned with the hypothetical Planet Nine; those colored blue are anti-aligned. The three pink orbits are Sedna and two similar objects. Orbits colored brown are objects that come closer to the Sun than Neptune’s orbit. The predicted orbit of Planet Nine is in yellow. Credit: Nrco0e/Wikimedia Commons" (Astronomy, Does Planet Nine exist?)

Four exotic things that Planet 9 could be. 

1) Black hole. (That can be in far longer distance than 550 times Earth's distance from the sun. That 550 times Earth's distance from the sun is Planet 9 predicted distance from the sun) 

2) Coherent gravity wave

3) Miniature white dwarf. (Planet that pressed into extremely dense form) 

4) Coherent dark energy. (Nobody has seen that thing yet. But it's possible. That dark energy can have a coherent shape, like all other wave movements have). 

The temperature of that planet will be really low and the difference between energy levels on the day- and night sides can make it possible for energy to travel out from its sun side and that can make planet nine or planet X invisible to us. 

The interesting thing is that the very strong gravity effect doesn't cause some anomalies in Uranus, Neptune, and dwarf planet's atmospheres. Also, interesting observations are the X- and gamma-ray flares on Uranus's atmosphere.  That phenomenon can form when something accelerates cosmic particles. 

But can "Planet X" or Planet 9 be something different than we even imagine? There are calculations that Planet X's mass is something between Mars and ten times that of Earth. So could planet 9 be something small and dense? There have been introductions that this mysterious object can be grapefruit-size black holes. 

An interesting thing is that Planet Nine can be a very dense object. All dense objects are not black holes. That means it can be a very tightly packed material. That is far heavier than any material on Earth. That means it's theoretically possible that the large planet can packed to a similar form as some white dwarfs. 

When high-power energy impulse hits the planet it can turn the planet's atmosphere hotter than the planet's nucleus. That effect can push the planet into a small size very dense object. The energy that presses the planet can turn it into a dense object that can have a white dwarf's, neutron star's, or even black hole's density. 

So the object can be very small in comparison with its gravity effect. And that makes it hard to detect. When energy hits an object, its mass will increase. And that thing can mean that something that we think is a dwarf planet can be a dwarf planet with steroids. 

Actually, the mysterious gravitational effect in the Kuiper belt can be something that we even cannot imagine. It can be the coherent gravity wave structure. Or something that we have never seen yet. 

https://www.astronomy.com/science/does-planet-nine-exist/