Astronomers May Have Detected an Atmosphere Around a Tiny, Icy World Past Pluto

"The Associated Press is reporting on a new study in Nature Astronomy suggesting that a tiny, icy world beyond Pluto harbors a thin, delicate atmosphere that may have been created by volcanic eruptions or a comet strike," writes longtime Slashdot reader fahrbot-bot. From the report: Just 300 miles (500 kilometers) or so across, this mini Pluto is thought to be the solar system's smallest object yet with a clearly detected global atmosphere bound by gravity, said lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan. This so-called minor planet -- formally known as (612533) 2002 XV93 -- is considered a plutino, circling the sun twice in the time it takes Neptune to complete three solar orbits. At the time of the study, it was more than 3.4 billion miles (5.5 billion kilometers) away, farther than even Pluto, the only other object in the Kuiper Belt with an observed atmosphere. This cosmic iceball's atmosphere is believed to be 5 million to 10 million times thinner than Earth's protective atmosphere, according to the the study [...].

It's 50 to 100 times thinner than even Pluto's tenuous atmosphere. The likeliest atmospheric chemicals are methane, nitrogen or carbon monoxide, any of which could reproduce the observed dimming as the object passed before the star, according to Arimatsu. Further observations, especially by NASA's Webb Space Telescope, could verify the makeup of the atmosphere, according to Arimatsu.

Meanwhile...

[Randseed]

Meanwhile, back in a secret bunker, hidden beneath a nondescript concrete building:

General: Mr. President, it appears that we have located... Planet X!

Georgio: I'm not saying it's aliens... but it's aliens.

Sitchin: It's Nibiru! The Anunnaki are returning!

Non-paywalled source

[Tx]

A preprint of the article is available on the arXiv (https://arxiv.org/pdf/2605.02243 [arxiv.org], for those that don't have access behind Nature's paywall.

Re:

[Tx]

*paper

Re:

[RockDoctor]

Thank you - I was just setting up to do exactly that.

Math conversion

[null etc.]

circling the sun twice in the time it takes Neptune to complete three solar orbits

Even more impressive, it circles the sun four times in the time it takes Neptune to complete six solar orbits!

Similar to that of Pluto, but let's sensationalize

[Fly Swatter]

Or very roughly 250 "Earth years." In fact it's almost exactly the same as Pluto at 248 years. Why all the fractional crap - it's nearly the same as Pluto*.

* Formerly known as a Planet.

Re:Similar to that of Pluto, but let's sensational

[Anonymous Coward]

It's interesting to people who understand orbital dynamics

The 2:3 orbital resonance is the primary reason that Pluto and other plutinos (like 2002 XV93) can exist in stable orbits despite crossing Neptune's path.This specific ratio provides several critical evolutionary and mechanical benefits:

1. Collision Avoidance ("Phase Protection")Even though many plutinos have highly elliptical orbits that technically cross inside Neptune’s orbit, they never actually collide or even come close to the planet. The 2:3 resonance ensures that whenever a plutino reaches its perihelion (the point closest to the Sun where it crosses Neptune's path), Neptune is consistently a quarter of an orbit away. This "phase protection" keeps them at a safe minimum distance of billions of kilometres at all times.

Re: Similar to that of Pluto, but let's sensationa

[ThurstonMoore]

Then maybe they should have put that info in the article for those interested in reading Nature for their orbital dynamics fix.

Re:

[RockDoctor]

It's a paper aimed at professionals in the field (or at least, trainee professionals in the field), not a Wikipedia page or an introductory textbook for American school pupils.

You know, I bet you didn't read a word of the paper. Not even far enough to note the "Abstract" section, and the football team (OK - volleyball team?) of author names and institutions. Which are rather give-aways for something being a paper, not a magazine article.

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[Tablizer]

Perfect ratios? Proof God-diddit! Now pray and lock up trans, like Fox Jesus wants! /s

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[sabbede]

Your math is off. So was mine the first time. For every 2 Neptune orbits, this sucker orbits 3 times. That means it must be orbiting faster than Neptune (164.8 years), not slower. That 2:3 ratio means it takes 2/3rds the time to orbit that Neptune does, so its period is more like 109 years. Put another way, it's 50% faster than Neptune, with 1.5 orbits for each of Neptune's. Which is shockingly fast and violates the otherwise consistent relationship between the radius and period of planetary orbits.

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[Fly Swatter]

circling the sun twice in the time it takes Neptune to complete three solar orbits

thats 2x for 2002 XV93 versus 3x for Neptune. that is slower than Neptune.

direct form the summary. check your dyslexia, it's something I am always aware I have and double check.

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[sabbede]

Aw, hell, you're right. That's what I get for trying to do math while still half-asleep.

Still faster than Pluto despite being further out, right?

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[RockDoctor]

Since both tails (orbit of Pluto ; orbit of (612533) 2002 XV93) are wagged by the dog of Neptune's orbit, and are constrained (and adjusted) by orbital resonance to stay very close to 3/2 of Neptune's orbital period, then both of their average orbital speeds will be similarly constrained by Neptune's orbital speed.

There will be a variation between the perihelion speed and aphelion speed, but that will average out over the orbit. Check Kepler's Laws.

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[sabbede]

Variations between perihelion and aphelion are irrelevant if you're comparing the orbital periods, right? I'm not interested in velocity at any point, just the total time it takes to orbit. If this sucker is further out than Pluto (and I don't know if it always is), then it should take longer than Pluto to complete an orbit but instead it takes a year or two less.

Or am I missing something else? I'm pretty far from being an expert in orbital mechanics.

Re:

[RockDoctor]

The previous posts were about periods. You seemed to shift to considering orbital velocities (or speeds ; it's not precisely clear), which is a different thing.

Yes, the tie to the period of Neptune's orbit should also constrain the period of the Plutinos over a suitable averaging period. But when you get to things like "tadpole" and "horseshoe" orbits, that can have significant variations of order-of a percent in period, resulting in the longitude of perihelion (direction of perihelion of the orbit, measure

Re:

[sabbede]

Well, I was always talking about orbital period (sidereal). I don't know why the velocity at any point in the orbit came up. I know its velocity will vary, just as Pluto's will. But if Goofy (thanks for that) is further out than Pluto, that Goofy completes an orbit in less time than Pluto does is pretty interesting since it should take longer.

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[angel'o'sphere]

Did you notice that the new discovered 'non planet' is called a 'Plutoist'?

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[RockDoctor]

'non planet' is called a 'Plutoist'?

To quote the paper's Abstract (becasue I haven't got to reading the body yet ; nobody has raised a point that has needed me to read that far, yet :

A stellar occultation by the ~ 250-km-radius plutino (612533) 2002 XV93 on

And :

Our findings indicate that a fraction of distant icy minor planets can exhibit atmospheres possibly caused by ongoing cryovolcanic activity or a recent impact event of a small icy object.

This is a "small icy object" (they don't even waste considerat

Re:

[angel'o'sphere]

Because I am not obsessive.

I just find it absurd to demote Pluto to a non planet and then classify other climbs as Plutino, is pretty inconsistent.

However, if the point is to be in resonance with Neptune, it "kind of" makes sense.

But then again: you could call them Neptino, or something, or? And Pluto would be a Neptino,too.

Re:

[RockDoctor]

I just find it absurd to demote Pluto to a non planet and then classify other climbs as Plutino, is pretty inconsistent.

IIRC, the term "plutino" was being used *before* the 2006 (?) IAU definition. Cart and horse sequence race condition.

But then again: you could call them Neptino, or something, or? And Pluto would be a Neptino,too.

There are bodies in a 3:2 resonance with Neptune. And other bodies in a 5:3 resonance (while 6:3 or 3:1 resonances are relatively empty : see "Kirkwood gaps" in the asteroid belt

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[RockDoctor]

A propos not a lot - my BOINC installation of "Asteroids@Home" has just started kicking through computations for the first time in ages. (BOINC is an indirect descendent of the SETI@Home project, generalised for a variety of distributable computation projects ; Asteroids@Home [asteroidsathome.net] is a project that "uses power of volunteers' computers to solve the lightcurve inversion problem for many asteroids." Lightcurves are brightness versus time ; once you correct for distance asteroid to Sun and asteroid to Earth, the cro

H2S content

[ahoffer0]

Reminds me of that time I detected an atmosphere around Uranus. It was primarily N2 and CH4, but had a surprisingly high H2S content. It lingered, then dissipated.

Great marketing for Aphelion!

[David E. Smith]

I'm impressed with Dontnod's marketing - actually putting a planet on the far edge of the solar system, to promote their new game "Aphelion" which is set on a previously-undiscovered planet on the far edge of the solar system. That's commitment.

Re:

[RockDoctor]

Has someone been putting something in the water? That's the second 4-digit UID I've seen in the last few days - and I've barely touched the Slash for months.

Nah, it's a simulation

[RogueWarrior65]

It's just people playing ArcticFox on an Amiga 1000.

Beyond Pluto

[Pf0tzenpfritz]

We all know which unspeakable horror lies beyond Pluto ...Yoggoth! We're doomed. As if things weren't terrible enough already.