I have to wonder if the Planetfinder project, which in part finds these planets in other system by them passing between us and their sun and dimming their sun’s apparent output – whether on or more of those planets may have been “discovered” because our own Planet X was eclipsing some other suns.
I really wish they hadn’t used the phrase “clearing the neighborhood around its orbit” in that definition. It’s caused way too many misunderstandings. A better term would be “dominating the neighborhood around its orbit”. It would have resulted in fewer misunderstandings. Maybe different ones, but fewer.
One of the ways that planets can “clear” their orbits is to force smaller bodies into resonant orbits such that the smaller body never comes anywhere close to a collision with the planet. This is why Pluto and the other plutinos that cross Neptune’s orbit do not make Neptune a non-planet.
In the case of Planet Nine, its existence has been deduced from about a dozen or so objects that seem to be in such resonant orbits. If it does exist, I would expect most of the other bodies in that region to be in resonant orbits as well. Any number of smaller bodies could be in such orbits with pretty much any total mass and it wouldn’t make it a non-planet.
There was a very thick thorny cypress hedge in my cul-de-sac growing up that most of our baseballs disappeared into. I’d start looking there.
It’s interesting that Planet IX seems to be in the sweet spot of being large enough to influence orbits, but small enough to not be a large IR radiator (the WISE satellite probably can’t see it). Definitely very tricky to spot directly.
Naive question:
So the primary evidence supporting the new planet hypothesis is the collection of Kuiper belt objects with similarly unusual orbits. Such a collection would not be expected by random chance, but neatly fits models of the solar system when a new planet is added.
How do we know that this collection isn’t due to some bias in the discovery of Kuiper belt objects? Would the surveys that detected them also be expected to find other Kuiper belt objects with completely different orbits?
And no cheating by searching in broad daylight. The baseball is dark grey, and you can only look for it at night. With no flashlights. And you have to wear sunglasses. And the only way you can distinguish it from millions of other baseball-sized stones is by glacially slow movement.
[Not sure how I missed this earlier.]
That will not be the case. When we discover a planet because it dims the light from a star, it has to repeat at least twice (and preferably more) before it’s confirmed. There are a number of other things that can cause a dip in the output of a star, so we need a regular pattern of such dips to conclude that it is a planet.
Another difference is that a Solar System object in front of a star (an occultation) will block the star completely, while a planet near the star will only dim it slightly. BTW,occultations, if predicted in advance, can be used to find out things about the object doing the occulting. For instance, the diameter of Eris was determined by timing its occultation of a star.
I’m curious, noting the “we”, are you personally involved in the project? I was a volunteer … observer? … for it for maybe a year or so when I was unemployed, but I kind of faded out after getting a job, and not finding anything of course.
Oops, thought I’d removed all the "we"s in my post. I’m just an interested bystander, not actively involved in any such project. If I use a first person plural pronoun, it refers to the astronomy community (or humanity) as a whole. But I try not to phrase it that way and rewrote part of my post to avoid it. Just didn’t rewrite enough of it.
One thing I’ve not seen mentioned in any discussion of HP9 (Hypothetical Planet 9), is that some models of Solar System formation require that a large planet get ejected due to the resonance in Jupiter’s and Saturn’s orbits.
Is it possible this near-discovery could confirm these models?
This near-discovery doesn’t confirm anything. It’s just a computer model and could easily be false. A real discovery would, because pretty much the only way for such a large body to get out there is by ejection from closer-in parts of the Solar System and subsequent modification of the orbit.
Bumping this thread because there’s more evidence for this ninth planet: a newly discovered rocky body, with an atypical tilt to its orbital plane that could be explained by the existence of a massive planet (way, way) beyond Neptune.
The name 2015 BP[sub]519[/sub] just rolls off the tongue, doesn’t it? It laughs and points at Planet X.
No, wait. It sort of is pointing at Planet X. Not sure about the laughing.
Yet for each dream these winds to us convey,
A dozen more of ours they sweep away!