Discovering Planet Nine | Hacker News Reader

Discovering Planet Nine

newyorker.com

54 pointsjwmerrill43 comments

I would love an update on efforts to find planet 9, unfortunately this article is from January 2016. See [1] for a Hacker News thread from Jan on Planet 9, and [2] for a blog from Batygin and Brown.

[1] https://news.ycombinator.com/item?id=10939306https://news.yc...

[2] http://www.findplanetnine.com/

If you are interested in latest research about planet 9 you can subscribe to https://www.reddit.com/r/planet9 - I'm trying to keep this subreddit up to date as much as possible.

The most interesting alternative to the Planet Nine hypothesis (and to my mind a more attractive one) is that there is a self-organizing dynamical process that applies to large ensembles of bodies in highly eccentric orbits that causes their argument of perihelion to become correlated.

There is a great SETI talk by the astronomer Ann-Marie Madigan that explains the idea, it should be easy to follow if you've ever taken a mechanics course: https://www.youtube.com/watch?v=YW0Zb5gY0HA

To quote Mike Brown (who has the best Twitter handle ever), "Weekly PSA: no, in fact the earth is NOT going to be destroyed by [fill in crazy thing seen on internet here] next week. Thanks for asking." https://twitter.com/plutokiller

I'm no expert (and have not read the full article, just about half of it), but could an object like this affect Earth when it's orbit gets closer to the sun? I mean anything, from causing movements in Earth's crust or below, influencing tides, carrying massive pieces of rock in its trail etc.?

If I remember correctly from the article, if this object were capable of perturbing Earth in any significant way, then we would be under much greater threat from Jupiter and Saturn, which are at least order of magnitude closer to us at any given time. Gravitation is a very weak force, and it scales as the inverse square of the distance between two objects. An order of magnitude reduction in distance would multiply the force by roughly 100 times. Thus, we would see these effects all the time as a result of our proximity to Jupiter and Saturn.

So no, what you're suggesting is impossible.

What was this nonsense I remember from gradeschool about planets aligning having a gravitation effect on the sun such that it'd start spewing fireballs at earth? Of course nothing happened. The amount of gravitational force from a mountain as you drive by it has more of an effect than the planets. It's kinda like, how does astrology affect us again? Can you be precise? I mean, other than for entertainment as by its own standard it's a real thing.

This could be awesome for a slingshot manuever on the way to alpha cent, right.

Does anyone know how to calculate that?

It wouldn't, actually, because gravity assists only add as much as the body's orbital velocity, which would be tiny for an object in such a distant orbit.

That doesn't sound right because it got the voyagers to leave the solar system.

He's correct. Remember how much further out planet 9 would be from the sun than Jupiter is. The speed at which an object orbits is related to how far away it is - note that the article said it has a really long year, too. Consider how far away geostationary satelites are compared to the ISS. The ISS goes around the planet several times a day, but geostationary orbits by definition complete one orbit in one day.

It is, that's how it works. Relative to the planet the incoming and leaving speeds are the same, but during the flyby the trajectory relative to the planet's orbital motion changes. So if you come in from the "side" of the orbit and leave headed in the same direction as the orbit, you'll increase your velocity relative to the Solar System by the speed of the planet. But that's the most you can gain from that.

Jupiter is the best planet for orbital slingshots not because it's going the fastest, it isn't, but because it's high gravity makes it easy to "bend" the trajectories of spacecraft a lot, so you can gain a bigger percentage of the orbital speed easier, which makes for a higher total speed.

Here's a table of orbital speeds: http://www.sjsu.edu/faculty/watkins/orbital.htm

Here's a graph of Voyager 2's speed throughout it's journey through the Solar System: https://solarsystem.nasa.gov/basics/bsf16-22.gif

And here's Voyager 2's trajectory: http://i.imgur.com/ctbjmMW.jpg

Notice how extreme the changes in direction are for the passes by Jupiter and Saturn, versus Uranus and Neptune. They are very sharp curves, that go from nearly approaching the planets from the side to leaving nearly in the same direction as the planets are moving. You can pick up at most 43% of Earth's orbital speed from a single gravity assist at Jupiter, but that's still a significant amount.

Additionally, as you can see from the second link, the farther out you are from Earth (at least in the more inner parts of the Solar System) the more bang for the buck you get from speed increases, because you're higher up out of the depths of the gravity well.

It seems pretty unlikely it is in the right plane. And even if it is, with its extremely long orbit, we would have probably have to wait at least 10,000 years before it was in the right position.

Pluto is planet nine.

This is 'planet ten', it's called 'Nibiru', and the Babylonians, Sumerians and Akkadian among others have astronomical records of it over 3,600 years ago.

tin foil hat time I do wonder if that's why Pluto was demoted, so when the 'tenth' planet was found it'd actually be called the 'ninth' so nobody would be as concerned about all the doomsday myths surrounding it.

https://en.wikipedia.org/wiki/Nibiru_cataclysm#Scientific_re...

If Pluto is #9, what numbers are Ceres, Sedna, Eris, Haumea, and Makemake? Ceres was considered a planet until the 1850s.

Astronomers think there are a few hundred more such dwarf planets, with 2007 OR10, Quaoar, Sedna, Orcus, (307261) 2002 MS4 and Salacia as likely candidates.

Which numbers are those?

The hypothetical planet the New Yorker mentions has an orbital period between twelve and twenty thousand years. Sitchin says the Babylonian religious texts say the period is 3,600 years.

These are not the same planet.

>> If Pluto is #9, what numbers are Ceres, Sedna, Eris, Haumea, and Makemake?

I don't care about them. This is a cultural issue. There is no fundamental principal governing how humans are to name space rocks. This is map making. Exceptions and one-off special rules are made all the time. We accept europe and asia as separate continents. If that can be a thing, then Pluto can remain a planet.

Then it's a good thing I was asking Cozumel, who does care and believes it to be significant, instead of someone who doesn't care.

You put them up to illustrate the consequences of a change to the planet-naming rule. I dismiss those consequences as irrelevant to the issue given how our culture is already so accepting of similar situation ... just in simpler words.

I was certainly not trying to do as you proposed.

I put them up there to illustrate that the views stated by Cozumel were contradictory, and to give Cozumel a chance to re-think the validity of the proposed tin foil scenario.

If Cozumel believes Pluto is really #9, then why does Cozumel not think that Ceres is a planet, making Pluto #10, which is the foretold doomsday planet X = Nibiru?

Or if Cozumel prefers the fringe views of Sitchin's twelfth planet, then why don't Makemake and the other dwarf planets count while Pluto, according to Cozumel, does?

Or not remain a planet because it's all arbitrary anyway. The classification is not meant to align to some sort of cosmic ordering, but to classify things in ways that are currently useful to science.

I don't like the classification of dwarf planet. The classification should be based on its size, shape, and make up. Instead they classified it based on the number of objects in its orbit, which is so arbitrary and weird. If hypothetically we cleared up the objects and dumped them in Earths orbit, Pluto would suddenly become a planet and Earth would lose its classification.

Just bite the bullet and accept there are a lot of small planets in our solar system, or classify them based on size.

The odd phrase "clearing the neighborhood around its orbit" exists because people want to think of Ganymede (which is bigger than Mercury) as a moon, not a planet, which your proposal would do.

If hypothetically we moved the Earth so it orbits Jupiter, then it would be a moon, yes?

Yes I accept orbiting the sun and not another object, as a reasonable criteria of a planet. That's included in the old definition. The new definition goes well beyond that though. If there are asteroids and debris in it's orbit around the sun, it no longer counts as a planet. It's really weird, and it's only purpose is to exclude the newly discovered planets from that classification.

Yes, it is weird, but I disagree with your interpretation.

You wrote: "If there are asteroids and debris in it's orbit around the sun, it no longer counts as a planet." That Wikipedia link I pointed to says: "As to the extent of orbit clearing required, Jean-Luc Margot emphasises "a planet can never completely clear its orbital zone, because gravitational and radiative forces continually perturb the orbits of asteroids and comets into planet-crossing orbits" and states that the IAU did not intend the impossible standard of impeccable orbit clearing.[2]

It further lists a few attempts to define things more rigorously.

You write: "it's only purpose is to exclude the newly discovered planets from that classification". The same page also points out "In 2015, a proposal was made to use the criterion in extending the definition to exoplanets". This is from the same Margot, whose proposed criteria can "categorise a body based only on its own mass, its semi-major axis, and its star's mass."

> The classification should be based on its size, shape, and make up. Instead they classified it based on the number of objects in its orbit, which is so arbitrary and weird.

Why should it be one rather than the other? What harm or benefit comes from Pluto being called, or not being called, a planet?

> If hypothetically we cleared up the objects and dumped them in Earths orbit, Pluto would suddenly become a planet and Earth would lose its classification.

No, because the definition requires that a planet clears its own neighbourhood. Having a nearby technological civilization clean up its neighbourhood for it doesn't cut it.

> Just bite the bullet and accept there are a lot of small planets in our solar system

Dwarf planets, you might say.

>Why should it be one rather than the other? What harm or benefit comes from Pluto being called, or not being called, a planet?

It violates everyone's internal model of the word "planet". Everyone knows what a planet is, and the formal definition should try to match our internal models as closely as possible. To do otherwise feels wrong and arbitrary.

>No, because the definition requires that a planet clears its own neighbourhood. Having a nearby technological civilization clean up its neighbourhood for it doesn't cut it.

So now the definition is based on history? We can't determine what is a planet based on just observing it, we have to know how it came to exist in that state? If we ever travel to other solar systems, we will never be able to know whether they are true planets or not. For all we know aliens or other events cleared the orbits before we observed them.

>Dwarf planets, you might say.

Highly misleading. Dwarf implies it's just small, and if it was bigger it would be a regular planet. But the definition isn't based on size.

If it were bigger, weren't it clear its own neighborhood? Is there an example of a sufficiently large body that doesn't?

(I'm by no means an expert, that's why I'm asking.)

> If we ever travel to other solar systems, we will never be able to know whether they are true planets or not. For all we know aliens or other events cleared the orbits before we observed them.

I don't even.

I mean, I'm not unfamiliar with lame arguments, having presented many in the past. But this one...wow.

I've got one better. Planets orbit their star. What if the aliens have antigravity devices so a planetary-mass object doesn't orbit its star or some other planet. Then what will we call it?

("That's Not A Moon...It's A Space Station!" tells us that those people long ago and far away didn't think that moon had to orbit a planet.)

To add more fun to the pile, is the "rogue planet" PSO J318.5-22 a planet? https://en.wikipedia.org/wiki/PSO_J318.5-22 . And yes, the IAU has already considered this case.

I think the reason we are having this disagreement is our basic vocabulary was developed when we knew of the existence of far fewer types of objects orbiting the Sun than we do now, and we are trying to fit the new objects into our old vocabulary.

What aren't you understanding? Of course I don't seriously believe aliens move objects around the solar system. It's just a silly thought experiment.

The point is it seems absurd that the past history of an object should matter, for this definition. Like if it's a big round object orbiting a star, it's a planet. It shouldn't matter how it got there. It seems quite possible there could be cases where another object clears the orbit of another object. Perhaps not aliens, but a rogue planet.

I was trying to recreate the "star trek test" argument that I heard a real astronomer use. He was upset with the new definition, and made an analogy to start trek. On the show they don't wait around for 12 months to observe the planet and any objects in its orbit, let alone it's past history. He argued that any sensible definition should be possible to determine immediately.

Of course we are arguing about the definition of a word, and all arguments are subjective and appeal to intuition. But still there can be bad definitions.

> If hypothetically we cleared up the objects and dumped them in Earths orbit, Pluto would suddenly become a planet and Earth would lose its classification.

You seem to believe that if we cleared up those objects and dumped them into Earth's orbit, they would stay there.

Eventually over many years they would clear up. But for a time Earth would no longer be a planet.

Technically, planets are defined as celestial bodies with these characteristics, not astronomical bodies, and Earth, not being in the night sky, is not celestial. So if you want to play a technicality game then Earth might not be a planet right now.

That technical definition hasn't been in use for about 400 years, when the astronomers became Copernicans.

Here's an astronomy book from 1842 talking about the Earth as the third planet from the Sun, and like all planets it revolves around the Sun:

https://books.google.com/books?id=9AhbAAAAcAAJ&dq=planet%20e...

You could not be more wrong about your correction. Not only is this definition current, it is in no way predicated on planets revolving around the Earth. The current IAU definition of a planet (the one that demoted Pluto) is:

"A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit."

Very clearly says celestial body. The IAU does not seem to draw a distinction between celestial and astronomical bodies, and uses the terms interchangeably, but they are not synonyms. The distinction is usually irrelevant to those who need to make observations about astronomical bodies, so I can see why.

Isn't this just splitting hairs using the definition of "celestial?" If I were on Mars, then my observations of celestial bodies would certainly include observations of Earth. Can you please explain when the distinction is relevant?

While you are correct that I misunderstood you, and thought you were talking about "planet", astronomers use "celestial body" to include the Earth, and have done so since the 1800s. Your comment started "Technically", so I believe you mean to use the astronomy definition, in which case your statement "Earth, not being in the night sky, is not celestial" is using non-technical language where I expected it to use technical language.

Two modern examples of how "celestial objects" includes the Earth are https://www.iau.org/static/archives/releases/pdf/iau0915.pdf :

> Titan has long fascinated astronomers as the only moon known to possess a thick atmosphere, and as the only celestial body other than Earth to have stable pools of liquid on its surface.

and http://astroedu.iau.org/activities/blue-marble-floating-empt... :

> These astronauts were the first people to ever orbit a celestial body other than the Earth, ...

Now, three historical examples, the first from Youth's Book of Astronomy (1839), https://books.google.com/books?id=qZc-AQAAMAAJ&dq=celestial%...

> Their [the Chaldeans] ideas of the earth as a celestial body were also crude and imperfect.

The second from "A system of universal geography : or, A description of all the parts of the world, on a new plan, according to the great natural divisions of the globe, accompanied with analytical, synoptical, and elementary tables", vol. 1 (1847) at https://archive.org/stream/universalgeograp01maltuoft#page/n... :

> Theory of Geography. Of the Earth, considered as a celestial Body, and in its relations to the other celestial Bodies.

Since "considered as" isn't as strong as "is", here's the third example, from "Astronomy simplified" (1838), https://books.google.com/books?id=cWAEAAAAQAAJ&dq=celestial%...

> 5thly-That the Earth, like every other celestial body, moves with accelerated velocity during the perihelion, and ...

You are also right that "celestial body" in popular use is often treated as a synonym for "heavenly body". This is a pre-Copernican viewpoint, expressed in 1 Corinthians 15:40 as "There are also heavenly bodies and there are earthly bodies; but the splendor of the heavenly bodies is one kind, and the splendor of the earthly bodies is another."

However, you emphasized the technical definition, not the general culture use.

P.S. Did you mean "planets revolving around the Sun" instead of the Earth? Also, earlier you wrote "Earth, not being in the night sky, is not celestial", but I'll point out the Sun is also not in the night sky; is it also not celestial?

No, whether you clear your orbit is a very different question from whether your orbit is currently clear.

Reminds me of the humorous article where Australia gets demoted to a dwarf continent, leaving only 6.

Do you have any sources to back up any of these assertions, e.g. that this is what Sumerians called 'Nibiru', or that they had astronomical records of this/an object?

If I remember correctly, the "Planet X" / "Nibiru" stuff is largely tinfoil-hat territory (see the link dalke posted, as well as other articles [1-4]) - a hodgepodge of speculation, conspiracy theories, pseudoscience and -history, and literal interpretation of myths - as made evident by a cursory search on Wikipedia.

Planet Nine, though, seems to be something other [5] than this mess entirely.

As for the doomsday myths, I find them equally ridiculous whether the planet in question would be number 9 or 10 on our somewhat arbitrary planet-system.

[1]: https://en.wikipedia.org/wiki/Planets_beyond_Neptune

[2]: https://en.wikipedia.org/wiki/Mesoamerican_Long_Count_calend...

[3]: https://en.wikipedia.org/wiki/2012_phenomenon

[4]: https://en.wikipedia.org/wiki/Zecharia_Sitchin

[5]: https://en.wikipedia.org/wiki/Planet_Nine

Clearly all the evidence for the Sumerians, Lumerians and Brobdingnagians knowledge of Nibiru was covered up by the knights Templar in order to hide the fact the world is going to end next Wednesday afternoon just after the Sleestaks take over.

I adore outlandish conspiracy theories and this is an excellent one. Now, are the astronomers and government secretly working with the Nibiru aliens themselves to cover up the impending cataclysm? Could the sinister New World Order really be a Nibiru beach head? And were Erich von Daniken and David Icke right about everything?

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