alt.hn

5/21/2025 at 6:32:24 PM

Possible new dwarf planet found in our solar system

 https://www.minorplanetcenter.net/mpec/K25/K25K47.html

by ddahlen

5/21/2025 at 8:51:21 PM

I found the preamble at the beginning of the announcement charmingly dated:

> The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. > > Prepared using the Tamkin Foundation Computer Network

Looking up the Tamkin Foundation Computer Network: https://www.minorplanetcenter.net/iau/Ack/TamkinFoundation.h...

> The OpenVMS cluster consists of nine single-CPU workstations and one four-CPU server. All the machines are running the extremely robust and secure OpenVMS operating system. The twelve Alpha-based machines are arranged as an OpenVMS Cluster, allowing all machines to share disk storage, execution and batch queues and other resources, as well as simplifying system management.

Assuming "Alpha-based machines" is referring to the DEC Alpha, these computers are ~30 years old. https://en.wikipedia.org/wiki/DEC_Alpha

by astroalex

5/22/2025 at 2:31:41 AM

Maybe not as old. I deployed a few racks of HP Alpha DS25s in 2007-2008 before they were replaced with Itanium based Blades (running OpenVMS 8.4). I do not miss working with OpenVMS one bit. It was rock stable (basically an on/off appliance) but the user experience left me wanting (coming from Linux).

I can see how they may be still stuck on Alphas because unless they can somehow simply recompile for x86-64 OpenVMS, it’s a complete rewrite from scratch.

by 404mm

5/21/2025 at 10:47:10 PM

Could they not get more juice out of a single, modern server? I get porting over to a new system and migrating is a huge time suck and a good enough reason not to do it if everything is working, just seems excessive for 14 cores.

by bastardoperator

5/21/2025 at 11:05:52 PM

> Could they not get more juice out of a single, modern server

They could probably get more performance out of one core on a modern phone, never mind a single modern server. But you see some really old systems in a lot of equipment, not because the porting costs are expensive, but the certification of proving the new system works the same is more than the operational cost of the legacy equipment.

by Macha

5/22/2025 at 12:06:33 AM

I’ve heard of consultants who will virtualize systems like this in place using qemu emulation of CPUs like Alpha and Sparc and run it on a single server or in the cloud.

by api

5/22/2025 at 2:33:25 AM

Sure, but the capital and one-time cost of acquiring and shifting to the modern server would be non-zero, and it would entail some risk. (While OpenVMS is maintained and runs on newer systems, that doesn't mean the software that matters on the existing cluster would run without modification.)

It probably would save operating costs, and probably over a reasonably short window, if it was done successfully, though.

by dragonwriter

5/22/2025 at 2:24:30 AM

> Could they not get more juice out of a single, modern server?

Maybe the software they use won’t easily run on a modern server.

You could ask them, but you might have to hook up your modem and try to call them. Maybe they have a BBS you could leave your question on.

by rubitxxx10

5/22/2025 at 4:29:56 AM

In 2020 I toured the machine room and those boxes were powered off.

by ccgreg

5/21/2025 at 6:32:24 PM

The minor planet center is the clearing house of observations of objects in our solar system. They have announced a new dwarf planet today.

This object appears to be in a very eccentric orbit (0.948), and with an H magnitude of 3.55, so it is likely hundreds of km in diameter. Ceres for reference has a H magnitude of 3.33 (smaller H is bigger diameter).

If you want to know what H means: https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_Syste...

by ddahlen

5/21/2025 at 8:42:22 PM

If you want to view the orbit:

https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%...

by ddahlen

5/21/2025 at 10:59:06 PM

Thanks, it helps quite a bit to be able to visualize what they're talking about.

Out at 90 AU, and by the year 3000 is out at 500 AU, and that's still not anywhere near maximum distance. Looked like it was going to be 10,000+ years orbits or longer, and probably out at several 1000 AU at maximum.

Little skeptical it would even orbit normally with how heavily eccentric it is, and the extreme distance at maximum. Way... out beyond the heliopause / heliosheath / termination shock.

by araes

5/22/2025 at 4:52:12 AM

> and probably out at several 1000 AU at maximum.

The preprint announcing the discovery lists the semi-major axis as 838 au, so the major axis is 1676 au and aphelion is about 1630 au.

https://arxiv.org/abs/2505.15806

by jessriedel

5/22/2025 at 5:59:16 AM

Does anyone know if this has its PE in alignment with the other Sedna type objects found?

I think there is a tendency for them to have their PE out to one side and the AP out to the other giving a fairly obvious pattern indicating another larger object is shepherding the others into their orbits.

by mwaitjmp

5/21/2025 at 7:37:46 PM

> This object appears to be in a very eccentric orbit (0.948)

from [0]:

> Before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit (e = 0.248). Other Trans-Neptunian objects have significant eccentricity, notably the dwarf planet Eris (0.44). Even further out, Sedna has an extremely-high eccentricity of 0.855 due to its estimated aphelion of 937 AU and perihelion of about 76 AU

> ...

> Comets have very different values of eccentricities. Periodic comets have eccentricities mostly between 0.2 and 0.7, but some of them have highly eccentric elliptical orbits with eccentricities just below 1; for example, Halley's Comet has a value of 0.967

so possibly an ignorant question, as someone who's interested in astronomy but doesn't follow it very closely - when this is categorized as a dwarf planet, does that include "it might be a comet" as a possibility? or have they already ruled it out as a possible comet through other observations?

0: https://en.wikipedia.org/wiki/Orbital_eccentricity#Examples

by evil-olive

5/21/2025 at 8:08:59 PM

Dwarf planet versus comet/asteroid hinges on mass, basically its "enough mass to be roughly round" (technically it's called "hydrostatic equilibrium").

Back from the 1810's to the 1870's or so, most people considered Ceres, Vesta, and things like that to be planets- they were bodies that wandered around the solar system, that meant they were planets. When the numbers started to get into the 20's, everyone decided to create a new category, "asteroid" (Greek for 'star-like') and put all of the smaller things in that. So when Pluto was discovered in 1930 it was slotted right into the planet category. Pluto was discovered mostly by accident, because Clyde Tombaugh was amazing at working the blink comparator, and finding the one dot that moved in between the two pictures of the night sky a few days apart.

However, by the 1990's and 2000's you had computers and digital cameras, which are even better than Clyde at finding things that move, and quickly the number of planets started to go up- and it was clear that once we had thoroughly mapped the ~~Oort Cloud~~ (meant Kuiper Belt, see below) etc. we would have dozens of planets. And so once again astronomers decided to create a new category, just like they had with asteroids a century earlier. This time they drew the line in such a way that Ceres got moved from asteroid to dwarf planet- it has enough mass to be roughly round, so after over a century of being an asteroid it became a dwarf planet.

This is how things always work in science: we discover something, then we discover more of them, and re-categorize everything based on the new discoveries. It's just more noticeable with Pluto because reciting the planets is done by every schoolkid in a way that they don't for subatomic particles or for species of voles or whatever.

by mandevil

5/21/2025 at 8:25:29 PM

> thoroughly mapped the Oort Cloud

So it’s interesting that the Oort Cloud is often mentioned as a real thing. Surely there are plenty of bodies discovered which are orthogonal to its existence, but Oort’s “Cloud” itself still enjoys only the status of hypothesis and not reality.

https://en.wikipedia.org/wiki/Oort_cloud

Sadly, even Wikipedia editors seem unable to distinguish between the formal definitions of “hypothesis” vs. “theory” when delivering such a scientific article.

by AStonesThrow

5/21/2025 at 8:45:50 PM

Oh wow, looks like I'm one of today's lucky 10,000! Thanks so much!

by codethief

5/21/2025 at 8:59:40 PM

You are correct, I meant to say Kuiper Belt, not Oort Cloud, pulled the wrong thing out of my memory. Unlike the Oort Cloud, we are doing a good job of mapping KBO's as we speak.

by mandevil

5/21/2025 at 10:55:07 PM

If the furthest objects of the Oort Cloud are over 3 light years away, it is relatively close to Alpha Centauri.

Is there a chance that Alpha Centauri also has its own cloud that overlaps with it?

Would AC influence the cloud and adjust the orbit of smaller comets?

by throwaway2k255

5/22/2025 at 12:08:15 AM

There's a chance, but no one knows for sure.

Oort Clouds are mostly empty space, so there wouldn't be much direct interaction. But there would certainly be gravitational effects.

My guess (FWIW) is there's more out there than we suspect, likely including plenty of rogue/wandering planets between systems.

by TheOtherHobbes

5/21/2025 at 8:34:51 PM

And that, boys and girls, is how Neil deGrass Tyson got Pluto demoted. (I kid).

by hinkley

5/21/2025 at 9:46:06 PM

I still think he did it because he wanted to have his name on something significant. He’s a science communicator, not a researcher, and he’s not going to be making any discoveries. So he’s gotta change something that already exists to have his name on something that everyone knows. He had the power to change its status, so he did. I think that’s all it was. I hope I’m wrong but I’ve never heard a really GOOD reason to undo something that was so commonly known and taught. The definition for “planet” could change and Pluto could have been left alone, grandfathered in, in a way. There’s a reason it was discovered first. It’s huge compared to other dwarf planets.

There’s no reason that Pluto couldn’t have remained a proper planet. It’s big enough to be round and its largest moon is big enough to be round. Mars doesn’t have any round moons. Mars is still a planet.

by naikrovek

5/22/2025 at 12:31:01 AM

He didn't "do it", he was one voice among many astronomers who have been calling for a reclassification for years, the IAU voted and made the decision. It's a little silly calling him out for "doing it" for ego reasons when you are the one implicitly giving him credit for it... He didn't write the definition, he didn't chair the committee, he wasn't even on the committee. All he did was leave it off the list of planets at the Hayden Planetarium, where he was director.

by dandelany

5/21/2025 at 10:22:20 PM

> The definition for “planet” could change and Pluto could have been left alone, grandfathered in, in a way

This doesn't sound like a science way of doing things. The definition of planet would have to be literally changed to add "Or has to have been discovered before 19XX" in order to keep Pluto without becoming an unbounded set. If you're annoyed at all the pedants correcting kids or anyone else talking about the nine planets, I'd take it up with them for uselessly debating such a fine distinction, like a chemist arguing about the word "Sodium" on a Nutrition Facts label.

I would argue the colloquial definition has indeed been changed in the above way, in that most people would say that what Mars, Venus, and Pluto have in common is they're all planets, and only a few would remember the odd factoid that the dwarf planet designation was created.

It's okay for the colloquial definition to be different than the scientific one. There isn't any use case where that will harm anyone. It's not like we're chartering flights to "All Planets" where space tourists are going to be ripped off, limited to 8 planets by the technicality and missing out.

by xp84

5/21/2025 at 10:33:10 PM

You’re probably right, but I still think there’s room for things like this.

What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not? Why is having a lot of planets a problem in the first place? Why do we have to restrict the definition at all? If 2-3 stars are at the center of a star system, are the planets in that star system planets, or something else? What if they’re small?

This whole scene is ripe for people who want to put their stamp of opinion on something to go nuts arbitrarily.

by naikrovek

5/21/2025 at 10:50:05 PM

What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not?

We already have the word "satellite" for "things that go around other things" right? I think "moon" is just "satellite of a planet" for convenience in discussing that subset.

> Why is having a lot of planets a problem in the first place?

I think keeping the number manageable is explicitly something we keep around to help kids grasp the main entities in the solar system. If we just said "there are 235 planets" it would be silly to try to teach them all, so we'd probably just settle for "The top 10 biggest planets" or something. Having a definition instead of a number to bound the set isn't much less arbitrary than teaching the "top 10," but since the long tail clearly starts after #8, "Top 8" would be the only guaranteed stable set to give special treatment to, which is what we've arrived at with the official definition.

by xp84

5/22/2025 at 12:33:19 AM

> Earth is a moon of Sol, is it not?

No. The sun is a star, so it doesn't get to have moons. It has planets. If Jupiter started generating heat from nuclear fusion reactions, we'd call Io a planet right before we boiled to death, and with our dying breath we'd add "and also, it's no longer a moon".

Putting a leash on a cat doesn't make it a dog, and both of those creatures have four legs even if you call the tails of each a leg. A planet revolves around a star, a moon revolves around a planet (revolving around a star). There's further elements which make Ceres and Ed White's lost glove not a planet or a moon, respectively, but planets and moons are distinct and non-overlapping categories.

by MyPasswordSucks

5/22/2025 at 5:38:29 AM

Why would we be boiling to death in this situation? Jupiter is much further from Earth than the sun is and Jupiter is also much smaller. Heat would increase, but probably not that much.

by ALittleLight

5/22/2025 at 12:12:21 PM

I would rather expect Earth to not have a stable orbit. Either ripped apart from fluctuating tidal forces, flung away or in one of suns (thus boiling would happen, briefly) or just generally a much more extreme place compared to now.

by jajko

5/21/2025 at 10:47:45 PM

> What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not?

Planets orbit stars. Moons orbit planets. That's a clear and easy distinction. Planet vs dwarf planet isn't so clear to most.

by rantallion

5/22/2025 at 12:34:32 AM

Don't planets and moons both orbit their center of mass? The distinction only seems to make sense if the masses of the two bodies are far apart. If they have similar mass, which is the moon and which the planet?

by amanaplanacanal

5/23/2025 at 11:35:17 AM

Indeed, before the planet/dwarf planet debate, Pluto and Charon were sometimes called a “binary planet” because their center of rotation is outside the volume of either body.

by Timwi

5/22/2025 at 12:35:12 AM

What’s a moon that orbits a moon? Doesn’t that make the orbited moon a planet? Pluto has moons. But it’s not a planet? ???

If a super massive planet and two stars orbit each other in the center of a star system, all the planets that orbit those stars are moons then technically, right?

This is all super fuzzy and completely arbitrary. These concepts are constructs. Humans could make them better. Instead, everyone decided to make it all worse.

by naikrovek

5/22/2025 at 3:09:25 AM

Don't forgot about moonlets!

by x______________

5/22/2025 at 3:33:24 AM

No. A star is not a planet. The bodies orbiting the stars are planets, or dwarf planets, asteroids or comets. Bodies orbiting them are moons. Bodies orbiting the moons don't have a name.

by gamblor956

5/22/2025 at 12:17:12 PM

> Bodies orbiting the moons don't have a name.

Satellites? Natural or manmade, small or big, doesn't matter.

by jajko

5/22/2025 at 3:56:23 PM

A natural moon of a moon is called a subsatellite: https://en.m.wikipedia.org/wiki/Subsatellite

At present, purely theoretical: we don’t know of any. They are probably quite rare, but we don’t really know - maybe, in centuries to come, we’ll know of dozens of examples; maybe, there are none to find in this entire galaxy

by skissane

5/21/2025 at 10:07:03 PM

Eris is essentially the same size as Pluto and has a larger mass.

by calmbell

5/21/2025 at 10:28:32 PM

Then ADD Eros. Don’t remove Pluto.

by naikrovek

5/22/2025 at 8:46:31 AM

Congrats, the solar system would then contain these planets:

Mercury, Venus, Earth, Mars, Ceres, Pallas, Juno, Vesta, Jupiter, Saturn, Uranus, Neptune, Pluto, Eris, Makemake

(Plus some more).

by kuschku

5/22/2025 at 12:20:52 PM

So what? Is 10 some mental limit of names for most population? If I can memorize 8 I can handle 12 or 15, or neither. Making up sub-categories is such a typical bureaucrat's approach to problems.

Why should giant planets be in same category as normal ones? Why mixing ringed with non-ringed? Why mixing moonless with moon-enabled? Gas/liquid ones and solids? I could go on for a long time.

by jajko

5/22/2025 at 5:18:44 PM

> If I can memorize 8 I can handle 12 or 15, or neither.

Current estimates expect about 200 Pluto-sized objects in the Kuiper belt and about 10'000 in the surrounding region.

Compared with 4 rocky planets, 2 gas giants and 2 ice giants.

by kuschku

5/21/2025 at 11:34:35 PM

Why?

by p_j_w

5/22/2025 at 2:54:28 PM

> Why?

Why remove Pluto?

The definition of a Planet could be whatever we want. It could be "these named entities are planets, other things are not planets" if we wanted. That makes a hell of a lot more sense to me than anything else, because eventually we are going to find planets which really blur the boundaries we have currently. Until we observe the entire universe, any set of rules we come up with are going to appear to be wrong in some situations.

by naikrovek

5/22/2025 at 11:01:28 PM

"It's not perfect so we should just do it arbitrarily instead" is a pretty silly scientific proposition.

by p_j_w

5/21/2025 at 10:01:15 PM

Isn't that kind of the issue though? Pluto's moon isn't just round it's about half the size of Pluto itself such that the Pluto-Charon system orbits around a point in space between the two bodies.

by XorNot

5/21/2025 at 10:26:23 PM

Jupiter and the sun orbit a barycenter, too. Jupiter is a planet.

by naikrovek

5/22/2025 at 12:09:29 AM

And the sun is a star. The point is the category exists to be useful: if Pluto is a planet then a ton of other stuff is technically a planet.

by XorNot

5/22/2025 at 2:55:53 PM

and in cases where the star is binary with a huge rocky planet? what are the large satellites in that star system? are they planets of the star, or moons of the huge rocky planet?

by naikrovek

5/22/2025 at 7:26:59 AM

Stop agonising over metadata. Pluto is still there and it’s not going anywhere.

by simondotau

5/22/2025 at 8:04:32 AM

The scientist who demoted Pluto was, in fact, Mike Brown (https://en.wikipedia.org/wiki/Michael_E._Brown), and he wrote a really nice book about it called “How I Killed Pluto and Why It Had It Coming”.

by elpres

5/21/2025 at 10:45:15 PM

I prefer to think that Pluto got denounced, and may yet be rehabilitated.MPAPA

by metalman

5/21/2025 at 8:25:04 PM

Very informative, thank you!

by epicureanideal

5/21/2025 at 8:26:14 PM

That wiki page needs some work. The section you linked to describes the eccentricity as a ratio, however the top of the page describes 0 as perfectly circular and 1 as an escape trajectory.

If it were a ratio then 0 would be escape and 1 would be circular.

by hinkley

5/22/2025 at 12:23:31 AM

The "Examples" section doesn't seem to talk about ratios, do you mean the end of the prior "Calculation" section? If so part is just saying you can calculate the ratio of r_a to r_p given you know e and run it through the equation, not that e itself = r_a / r_p (the formula to calculate e from r_a and r_p is higher up in the section).

If not that section, apologies for missing what you're trying to point out - I'm just trying to see what needs to be cleaned up so I can make an edit if needed.

by zamadatix

5/21/2025 at 6:45:48 PM

> hundreds of km

How big is that compared with other dwarf planets/ Moons? If you sort all dwarf planets by size, which position does this take (approximately)?

Pluto -> 2300 Km

Ceres -> 950 Km

Fobos(Mars) -> 25 Km

by gus_massa

5/21/2025 at 6:55:23 PM

Depends on the albedo, if the H magnitude is a good measurement, then it is probably between 300-700km. These are rough bounds, its highly dependent on how reflective it's surface is (albedo).

With an orbit somewhere around 28k years, it reached perihelion in about 1931, at 45 au from the Sun.

by ddahlen

5/21/2025 at 7:38:30 PM

So it's roughly in the closest 200-year period out of 28,000 years. That means it spends 99.3% of it's orbit further away than now, and thus harder to find.

Simplistic odds would seem to imply that there's over a hundred more dwarf planets just like this but further away, so we just haven't seen them.

by kbelder

5/21/2025 at 7:52:40 PM

I really hope we can get some more sensitive and wider telescopes to look deeper into the Oort cloud. At those distances, sunlight is comparable to a full moon or less, surface temperatures are only tens of kelvin. And yet they're still less than 1% of the distance to the next star.

by hnuser123456

5/21/2025 at 7:46:30 PM

[I'm lost with all the recent discoveries.]

Assuming 500Km, is in in the top 10 by size/mass[1][2]? Top 100? Top 1000? Top 1000000?

[1] Yes I know it's not the same. Whatever criteria is easier to measure.

[2] I guess not top 10, but I have no idea about the current knowledge of the long tail. Fake Edit: I took a look at https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets So between 20 and 30???

by gus_massa

5/22/2025 at 8:19:37 AM

Your comment was the one that really made all of this sink in, thanks. Wow.

by liamwire

5/21/2025 at 8:41:21 PM

This thread is making me realize that The Expanse has me pronouncing planetoids in Belter.

by hinkley

5/21/2025 at 9:31:55 PM

Beltalowda!

by temp0826

5/21/2025 at 7:15:16 PM

Does the 0.984 eccentricity orbit imply anything? That's close to eccentricity of 1, which is a parabolic path, not gravitationally bound to the sun.

by bediger4000

5/21/2025 at 7:58:13 PM

Going off the SMA and eccentricity, part of its orbit is "relatively" close to the sun, ~ 45 AU, about 1.5x the distance to Neptune (~ 30 AU), and the other half of its orbit is very, very far away, ~ 1700 AU, over 50 times the distance to Neptune, but still less than 1% of the distance to the next star.

When it's in the faraway part of its orbit, it is moving very slowly, probably only tens of meters per second, but it's still close enough to the sun to eventually fall back in for another loop.

However, if something else dense enough got close enough out there, it would be easily perturbed and have its whole orbit altered, or even be ejected.

But interstellar space is pretty void of wandering solid bodies, so it keeps falling back towards the sun.

by hnuser123456

5/21/2025 at 11:16:27 PM

> But interstellar space is pretty void of wandering solid bodies, so it keeps falling back towards the sun.

As far as we know ... we don't know how many rogue planets are out there ... mayb be as numerous as the number of stars or even greater

by SJC_Hacker

5/22/2025 at 8:51:47 PM

After I posted that, I did some more research to see how typical it is, over longer time periods, that our nearest star is about 4 ly away. That seems to be about average spacing for our part of the galaxy, but it turns out in a little over a million years, a star about half the size of the sun will pass around 0.15 ly away or 10,000 AU, which is far outside the kuiper belt, but solidly though the middle of the inner oort cloud, and will leave a wake of scattered comets and asteroids, some of which will rain down on Earth.

https://en.wikipedia.org/wiki/Gliese_710

by hnuser123456

5/22/2025 at 9:23:45 PM

Nice! I was hoping for a nearly parabolic orbit to mean this was an interstellar object captured by the sun's gravity.

by bediger4000

5/21/2025 at 7:41:28 PM

"That's no moon" :-). But more seriously, just another giant lump of stuff swinging around the solar system. I am not an astronomer, so I'm not sure about some of the things I'm reading in that report but to me, it seems to be in the solar ecliptic. But its far enough away even at perigee that the only thing of note it might interact with would be Pluto.

I suppose that flying through the Oort cloud it might periodically launch ice balls into the inner solar system.

by ChuckMcM

5/21/2025 at 10:11:35 PM

> But its far enough away even at perigee

Minor astrodynamics nit: "perigee" is a term specific to Earth. The generic term for all bodies is "periapsis", and the term for the Sun is "perihelion"

(Astrodynamics terms generally take from the Greek, rather than Latin)

by dabluecaboose

5/21/2025 at 8:11:17 PM

It boggles my mind when I look up at the Moon, that in fact it's a massive rock travelling at something like 2,000 mph, always trying to fall onto the Earth, and missing it all the time.

by rich_sasha

5/21/2025 at 8:25:43 PM

If my goal was to fall into the earth and kept missing I would be depressed too. Each try it misses by slightly more and it's orbital distance increases. How sad is that?

Also, I like to anthropomorphize inanimate objects because secretly they hate it.

by mgiampapa

5/22/2025 at 12:44:31 AM

Earth is also constantly failing at falling into the Moon.

Why did we have to evolve in such a loser system??

by BurningFrog

5/21/2025 at 8:31:42 PM

its getting further away, if it helps your understanding of the situation better

“falling into” was never part of the equation

by yieldcrv

5/21/2025 at 7:49:59 PM

only thing of note it might interact with would be Pluto

Is Pluto a planet again, or not? Honest question because I don't keep up on these things because they have no practical effect other than drama...and I try to avoid drama.

by brudgers

5/21/2025 at 8:07:51 PM

No. It’s smaller than other moons in our solar system. It’s never going to be a planet again, but a planetoid, dwarf planet, or even asteroid is appropriate.

by kulahan

5/22/2025 at 12:25:45 AM

Just to be pedantic, Mercury is also "smaller than other moons in our solar system"

And never is a long time, especially for something as fickle as human classification.

by GMoromisato

5/22/2025 at 2:11:23 AM

You’re right, it’s about gravitational domination.

by kulahan

5/22/2025 at 5:57:51 PM

Agreed.

My (uninformed) guess is they will eventually reclassify all non-moon objects in hydrostatic equilibrium (anything round) as planets, which will make Pluto a planet again and bring in a half-dozen new objects.

by GMoromisato

5/21/2025 at 9:04:51 PM

For the curious.

Periapsis, au: 45.241

Apoapsis, au: 1714.759

Period, years: 26106.07

by d_silin

5/21/2025 at 9:58:29 PM

26000 year period and yet it has still been around the sun 2000+ times since the dinosaurs went extinct. Make me feel a bit insignificant and awed at the same time.

by silverfrost

5/22/2025 at 8:35:20 AM

Humans probably can orbit the sun 2000+ times in a not significantly distant future

by buryat

5/21/2025 at 9:09:15 PM

It comes to Earth closer than Pluto, btw.

by d_silin

5/22/2025 at 12:05:13 AM

Specifically: when this object is at its closest and Pluto is at its farthest then this object can be the one closer to Earth. Pluto comes the closest of the two overall though.

by zamadatix

5/21/2025 at 8:57:08 PM

I got a bit too excited with this one, this is may not be a full on dwarf planet, but it is a very large object. There are only a small number (about 10-20) objects in our solar system of this size. Its the first big one we have found in a number of years.

by ddahlen

5/22/2025 at 12:48:41 AM

By "small number (about 10-20) objects in our solar system of this size" you are referring to the class of objects of a similar size rather than the largest objects in the solar system?

by calmbell

5/21/2025 at 7:15:43 PM

Sorry for a stupid question: could it be "the planet X", or is it too light / in a wrong orbit?

by java-man

5/21/2025 at 8:19:30 PM

This is a good question to ask. It can't be, for the reasons you guessed.

This is not the first time this sort of thing has happened. When Pluto was found by Clyde Tombaugh he was looking for Planet Nine, which Percival Lowell had calculated must be present based on the orbits of the outer planets. But it was quickly realized that Pluto was too small and in the wrong orbit for it be Lowell's deduced planet. (And even then they worked with a too high estimate of Pluto's mass, it wasn't until the 1978 discovery of Charon that we got a good estimate of Pluto's mass. It is hard to get a good mass estimate without something else in orbit around it.)

The Pioneer and Voyager missions gave us much better estimates of the masses of the gas giants, and my understanding is that if you go back and redo Lowell's calculations with those correct masses, his planet disappears. That's my best guess as to Planet X, that our constants are wrong in some way, but we'll see.

by mandevil

5/21/2025 at 8:47:36 PM

One of the other theories for Planet X I believe has been debunked as absense of evidence. There are gaps in the documented bodies orbiting the sun that could imply an object clearing orbits, but they were dismissed instead as sampling errors - there are parts of the sky that are easier to catalog than others, and so of course we have cataloged the easy parts more thoroughly. We need observation stations in a sun orbit to see the parts we can’t see easily from an earth orbit.

by hinkley

5/21/2025 at 7:30:34 PM

This is not planet X. This is smaller than other, closer, bodies that we already know of.

by dotancohen

5/21/2025 at 8:43:06 PM

And I just put the kettle on for the Anunnaki, what a pity.

by squidsoup

5/21/2025 at 7:26:32 PM

No, according to Wikipedia Planet Nine is expected to have about 5 earth masses.

by porkbrain

5/21/2025 at 11:26:13 PM

They prefer to be called little planets

by tomcam

5/22/2025 at 4:45:31 AM

Welcome to the neighborhood!

by jsnider3

5/22/2025 at 12:35:47 AM

[dead]

by aaron695