7 ms·
Possible new dwarf planet found in our solar system
- ddahlen 1y agoThe 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_System_bodies_(H) https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_Syste...
- gus_massa 1y ago> 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
- ddahlen 1y agoDepends 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.
- kbelder 1y agoSo 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.
- hnuser123456 1y agoI 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.
- gus_massa 1y ago[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 https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets So between 20 and 30???
- liamwire 1y agoYour comment was the one that really made all of this sink in, thanks. Wow.
- hinkley 1y agoThis thread is making me realize that The Expanse has me pronouncing planetoids in Belter.
- temp0826 1y agoBeltalowda!
- bediger4000 1y agoDoes 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.
- deleted 1y ago[deleted]
- hnuser123456 1y agoGoing 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.
- SJC_Hacker 1y ago> 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
- hnuser123456 1y agoAfter 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 https://en.wikipedia.org/wiki/Gliese_710
- evil-olive 1y ago> 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 https://en.wikipedia.org/wiki/Orbital_eccentricity#Examples
- mandevil 1y agoDwarf 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.
- ddahlen 1y agoIf you want to view the orbit: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%20OF201&view=VOP https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%...
- araes 1y agoThanks, 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.
- zamadatix 1y agoThe fun part is the ~1700 AU aphelion is still not far enough out to be part of the Oort cloud. https://science.nasa.gov/solar-system/oort-cloud/facts/ https://science.nasa.gov/solar-system/oort-cloud/facts/
- jessriedel 1y agoWell, the preprint announcing the discovery describes its orbit as extending to "the inner Oort cloud" even though aphelion is 1630 au. https://arxiv.org/abs/2505.15806 https://arxiv.org/abs/2505.15806
- jessriedel 1y ago> 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 https://arxiv.org/abs/2505.15806
- mwaitjmp 1y agoDoes 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.
- d_silin 1y agoMost likely a https://en.wikipedia.org/wiki/Detached_object https://en.wikipedia.org/wiki/Detached_object
- java-man 1y agoSorry for a stupid question: could it be "the planet X", or is it too light / in a wrong orbit?
- porkbrain 1y agoNo, according to Wikipedia Planet Nine is expected to have about 5 earth masses.
- dotancohen 1y agoThis is not planet X. This is smaller than other, closer, bodies that we already know of.
- squidsoup 1y agoAnd I just put the kettle on for the Anunnaki, what a pity.
- mandevil 1y agoThis 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.
- hinkley 1y agoOne 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.
- deleted 1y ago[deleted]
- ChuckMcM 1y ago"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.
- brudgers 1y agoonly 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.
- kulahan 1y agoNo. 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.
- GMoromisato 1y agoJust 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.
- kulahan 1y agoYou’re right, it’s about gravitational domination.
- GMoromisato 1y agoAgreed. 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.
- astroalex 1y agoI 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.html 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 https://en.wikipedia.org/wiki/DEC_Alpha
- bastardoperator 1y agoCould 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.
- Macha 1y ago> 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.
- api 1y agoI’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.
- ddahlen 1y agoI 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.
- calmbell 1y agoBy "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?
- d_silin 1y agoFor the curious. Periapsis, au: 45.241 Apoapsis, au: 1714.759 Period, years: 26106.07
- d_silin 1y agoIt comes to Earth closer than Pluto, btw.
- zamadatix 1y agoSpecifically: 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.
- silverfrost 1y ago26000 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.
- buryat 1y agoHumans probably can orbit the sun 2000+ times in a not significantly distant future
- tomcam 1y agoThey prefer to be called little planets
- deleted 1y ago[deleted]
- aaron695 1y ago[dead]
- calmbell 1y agoHere is the arXiv preprint: https://arxiv.org/abs/2505.15806 https://arxiv.org/abs/2505.15806
- jsnider3 1y agoWelcome to the neighborhood!