It is only evidence that at some moment in the past there was something big out there, which has perturbed their orbits.
In 2024 there have been published a few papers which propose that a star has passed close to the Solar System in the past and its passage has caused all the unusual orbits that we see in the outer Solar System.
This seems more plausible than an undiscovered big planet.
Both are plausible, both are intriguing. To determine what in fact happened there's no way around looking up and searching until we exhaust the possibilities. Kudos for Terry Phan and his team for putting in the work, regardless of what hypothesis it ends strenghtening.
Unusual values of the orbital parameters are only evidence for something that has happened in the past.
Yes, unusual values for orbital parameters are only evidence that something happened in the past, but that thing that happened in the past might have been "close approach with a planet". And as a hypothesis, this is in no way less valid or likely than a flyby with a star.
There is no such thing as a degradation of an orbit.
The fact that the clustering has not degraded is actually evidence for the opposite fact, that the body that has perturbed all those orbits is no longer there.
Apsidal precession makes the aphelion of eccentric orbits rotate around the Sun over time. The rate at which this happens depends highly on their orbital characteristics, meaning that if something perturbed their orbits to point in a specific direction, over a relatively short timescale (single digit millions of years), you would expect their aphelions to point in essentially random directions.
The fact that TNO orbits seem to cluster into specific directions is strong evidence that something is actively maintaining their orbits, by repeatedly perturbing them.
A large planet that's quite far out is a reasonable hypothesis for what's doing this. (It's not the only one.)
Why?
The parent article contains several sentences like "The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction."
All those sentences do not support the existence of an outer planet now, they only demonstrate that at some moment in the past there was a big body in that direction.
The papers that I have linked report the results for the simulation of the close passage of a star in the past, which match pretty well what we see now in the outer Solar System.
Such close encounters between stars are known to happen from time to time, because superposed on the general rotation around the galaxy center all stars have random own motions, so the distances between them are changing all the time and even collisions are possible.
Planet 9 might be confirmed with infrared surveys as a post from last week discussed or some other method.
There may be one or more big planets at great distances from the Sun, but not for the reason stated in the parent article, which is better explained by an ancient star flyby.
> The Solar System planets accumulated from a disk of dust and gas that once orbited the Sun. Therefore, the planets move close to their common plane on near-circular orbits. About 3,000 small objects have been observed to orbit the Sun beyond Neptune (rp > 35 au); surprisingly, most move on eccentric and inclined orbits. Therefore, some force must have lifted these trans-Neptunian objects (TNOs) from the disk where they formed and altered their orbits markedly.
I feel there is a strong bias towards objects that are only discoverable because of their highly eccentric orbit
There's also an alternative lesser known proposal for an undetected massive object in the outer solar system, by Lykawka and Mukai[1], ofter confounded with the planet nine hypothesis, but it is actually an independent proposal from the object predicted by Batygin and Brown. I wonder if despite not being compatible with the more known planet nine proposal, the recent finding may be compatible with the one from Lykawka et al, or it may even be the case that the former acts in tandem with the later, and we actually have two real objects making the work of the virtual single planet proposed by B&B.
[1] https://iopscience.iop.org/article/10.1088/0004-6256/135/4/1...
40 pages of two-column astrophysical journal survey and analysis.
I can see why it must be required reading for a discussion of TNO dynamics.
Wow.
The second-worst part is that we can't call this hypothetical trans-Plutonian planet "Planet X" anymore.
The operating system
The planet
The legend
Link to the paper:https://arxiv.org/pdf/2504.17288
I was curious what kind of resolution you'd have at this distance but not sure I did the math right. The camera has a resolution of 0.27"/pixel[1] which is 0.000075 degrees. Then to get size at 500AU -> tan((pi/180) * 0.000075)(500 149597870700) ~98megameters, which is like 8 earth diameters. Is this right?
[1]: https://www.darkenergysurvey.org/the-des-project/instrument/...
Resolving power is related to the PSF (Point Spread Function) size. The PSF is the image on your detector if you have an infinitely small point source. A quick google search says that DECam has a PSF of at least an arcsecond (atmosphere is probably causing issues for that). Which means anything smaller than an arcsecond is going to be unresolvable.
However, you still want pixels smaller than your PSF, since PSFs are typically gaussian-ish, having a bunch of measurements within the gaussian allows you to estimate the center accurately. This is vital for Astrometry (the measurement of position).
Astrometry.net is a service that does an approximate version of this on the web.
I am glossing over many details here, but this is roughly what happens.
For the curious wanting to go down this rabbit hole here seems to be an ESA archive dataset of 'GAIA Data Release 3' (released 3 June 2022) :
What is the proposed timeline of the passing of that other star?
Then you know god is a vicious cruel kid with a big magnifier glass fooling around his little ant farm.
(Disclaimer: I know nothing)
Or they left behind swarms of nanobots, which we call biological life. :p
I'm not saying interstellar travel is impossible, I'm just saying an early technological civilization in our solar system is more possible.
I think the likelihood that there was some technological civilization that evolved here before ours and we haven't found any trace to be extremely low. Lower than "there are people with warp drives who visited our solar system at some point".
(And as far as detecting relict machines: our astronomy is really not that thorough. They wouldn't even have to be hiding. Have we conclusively analyzed every little point of light in the asteroid belt? No.)
This reminds me of "lone rangers"
Fight me!