The new evidence of controversial planet 9.

"Planet Nine is a hypothesized massive planet, first proposed in 2014, that is speculated to orbit far out in the solar system. It has not been detected formally. Instead, astronomers have inferred its presence from perceived perturbations of the orbits of some Trans-Neptunian Objects (TNOs). The planet is estimated to be 2 to 4 times the radius, and about ten times the mass of the Earth. (Image credit: Mark Garlick/Science Photo Library/Getty Images)" (Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

"Planet Nine would appear to move on the sky because of parallax as Earth moves around the sun. On any particular day, it might seem to be in one position, then six months later when Earth is on the other side of the sun, it would shift to another position, perhaps by 10 to 15 arcminutes — then, six months after that, it would seem to shift back to its original position. To remove the effects of parallax, Phan's team searched for Planet Nine on the same date every year in the AKARI data, because on any given date it would appear in the same place, with zero parallax shift, every year." (Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

"They then also scrutinized each candidate object that their search threw up on an hourly basis. If a candidate is a fast-moving, nearby object, then its motion would be detectable from hour to hour, and could therefore be ruled out."(Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

"It appears in one position in IRAS's 1983 image, though it was not in that position when AKARI looked. However, there is an object seen by AKARI in a position 47.4 arcminutes away that isn't there in the IRAS imagery, and it is within the range that Planet Nine could have traveled in the intervening time. In other words, this object has moved a little further along its orbit around the sun in the 23 or more years between IRAS and AKARI. This careful search led Phan's team to a single object, a tiny dot in the infrared data."(Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

Can this be Planet X? Researchers found interesting details in AI-based old-data re-analyzation.  "A comparison of the position of the candidate object in the IRAS data (left) and the AKARI data (right) and the distance in arcminutes between them. (Image credit: Phan et al (2025))" (Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

""Once we know the position of the candidate, a longer exposure with the current large optical telescopes can detect it," Phan told Space.com. "However, the follow-up observations with optical telescopes still need to cover about three square degrees because Planet Nine would have moved from the position where AKARI detected it in 2006. This is doable with a camera that has a large field of view, such as the Dark Energy Camera, which has a field of view of three square degrees on the Blanco four-meter telescope." (Space.com/Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart)

Planet 9 might have a 23-year orbital period. The data that astronomers collected from space tells about disturbance. That repeats after 23 years. There are calculations that Planet 9 might have more mass than Neptune. And that planet's distance is about 700 times Earth's distance to the Sun. That means Planet 9 might be a frozen gas giant the long way out from the solar system. That means that if that planet exists it might be even colder than Pluto. 

There is the possibility. This kind of very cold planet's atmosphere acts like a black hole's halo. That means a very thin plasma around that planet can transport heat into its poles. Turning the gas flow into the poles. That gas flow acts like a thermal pump. The infrared radiation forms the pike-shaped structure. Similar to a neutron star's jet but very much weaker. This thing requires that the planet's own atmosphere is frozen. There is also the possibility that there are colder points in the planet's atmosphere or inside it. That makes energy flow into those colder points. 

The Iapetus moon of Saturn. "Iapetus as imaged by the Cassini orbiter in false color, September 2007. Iapetus's unusual coloration can be seen, with the equatorial ridge on the right limb. The large craters Engelier and Gerin are near the bottom." (Wikipedia, Iapetus_(moon))

The question is why we cannot see that object. One of those answers can be that dust between it and the sun can cover that planet's weak infrared signature. 

The maximum temperature of that planet might be near to 4 Kelvin. It would be roughly hotter. To the cosmic background. Or 3 Kelvin radiation. If the planet's temperature is about 0,5-5 percent higher than the cosmic background the dust can easily cover the planet's infrared signature. If dust is hotter than the planet. That makes it impossible to see it. 

Another explanation for the invisibility of Planet X can be that it's similar to the Iapetus moon. If one side of the planet is black that absorbs temperature and the other side is white that makes energy travel to the other side of the planet. That energy flow is always out from the Sun makes the planet extremely hard to detect. If the atmosphere travels to the side that is away from the Earth that causes the effect that the atmosphere can be very thin and acts like a thermal pump that makes a very unusual effect. 

That planet. If it exists is so far away from the sun that it's colder than Kuiper Belt objects. So IR radiation from those objects can cover it below it. That kind of place will freeze the planet's entire atmosphere. The thin plasma cloud makes it possible that the planet's dayside is colder than its nightside. 

Uranus's X-ray emission. "This composite image shows a Chandra X-ray image of Uranus from 2002 (pink) superimposed on an optical image from the Keck-I Telescope obtained in 2004. Image credit: NASA / CXO / University College London / Dunn et al." (SciNews, Chandra Detects X-Ray Emission from Uranus)

"This composite image shows a Chandra X-ray image of Uranus from 2002 (pink) superimposed on an optical image from the Keck-I Telescope obtained in 2004. Image credit: NASA / CXO / University College London / Dunn et al."  (SciNews, Chandra Detects X-Ray Emission from Uranus)

Sometimes impacts with its atmosphere raise the temperature.  And in those extremely frozen conditions, even the smallest temperature differences have a big effect. Conditions in the most out solar system are cold but stable. That means there are things. That is not possible near the Sun. One of those things is the plasma whirls that form magnetic fields around the dwarf planets. Near the sun the particle flow from the Sun the particle flow pushes those plasma fields away. But in the Kuiper Belt, the solar wind is very weak. 

There are many myths and theories about that mysterious object called "Planet 9" or "Planet X". When researchers talk about that object, they mean the mysterious gravity effect that disturbs Neptune's orbital trajectory. There are also theories that those interferences can be a very small black hole. The planet-mass black hole can form when things like relativistic jets hit planets. 

The small black hole can explain things like Uranus's X-ray flares. That thing would accelerate those particles at the speeds that make those X-ray flares possible. Those X-ray flares can also form when high-energy particles from Uranus's poles hit particles that come from the Sun. That can explain some of those mysterious X-ray flares. 

https://www.sci.news/astronomy/uranus-x-rays-09510.html

https://www.space.com/astronomy/solar-system/evidence-of-controversial-planet-9-uncovered-in-sky-surveys-taken-23-years-apart

https://en.wikipedia.org/wiki/Iapetus_(moon)