I think “15 times further from the Sun than Pluto” is more meaningful for most readers than “700 times further from the Sun than Earth.” If it exists, it’s way way way out there.
It makes even less sense for Earth because Earth's orbit is near-circular, whereas Planet 9's hypothesized orbit is highly eccentric, more so than Pluto.
Most people don't know off-hand that Pluto is ~40-50AU from the sun, so 700AU is hard to conceptualize.
They're all horrible to conceptualize because people don't commonly deal with how far even something like the Earth to the Sun is, I don't think there is any winning answer here - at least an AU is consistently defined and maybe slightly more likely to be familiar, but it's still just about as crap to be honest.
Side note: Apart from AU already being defined as average distance and not current distance, the distance referenced is how far out the proposed object is now, not its general orbital parameters. At that orbital distance 23 years of motion isn't going to be much change in distance even if it's in a hyperbolic orbit.
My point was not about intuiting the distance, it's about what the solar system looks like qualitatively, as a cartoon with orbits drawn around the sun. Most people have no idea if 700AU is closer than Pluto, a little further than Pluto, or much further than Pluto. 15x the distance of Pluto is much more direct.
What's the benefit of communicating something is 15x the distance of Pluto if people are expected to have at least a ~15x error in how far away Pluto is supposed to be? At that point it's all nonsense, nothing is relevant anymore. Might as well say something useful for those who do have a clue about the solar system.
Hell, it's been nearly 2 decades since Pluto was itself planet 9. Just bringing the name up in a discussion about planets is going to cause more confusion.
15 time further than the furthest once-planet is fairly intuitive to say really freaking far; you don’t need to know how far pluto is, just that it’s the furthest.
> Might as well say something useful for those who do have a clue about the solar system.
The source we are discussing is space.com, a website which frequently mentions Star Wars and whose stated mission is to "transport our visitors across the solar system and beyond through accessible, comprehensive coverage of the latest news and discoveries." My comment was about communicating this research in a way that better fits "most readers" of space.com. If you think qualitative orrery models are beneath you and want to exclude those people, then you are not the target audience. Just go read the actual paper.
I was just thinking of this XKCD comic specifically.
Most people won't even have the slightest idea what 1 AU is. Most people know less about most topics (including space) than the original ChatGPT (3.5) did — probably only people who at least started a degree with a space sciences module are likely to know more than 3.5, and I expect plenty of space.com readers to be enthusiastic amateurs rather than professionals.
That said, I do I expect the average reader of space.com to know what an astronomical unit is, but even so I don't expect them to know the average orbital distance of Pluto.
New horizons launched 9.5 years before it reached Pluto, and your average reader who has an interest in Planet 9 will likely know it took New Horizons about that long.
15x means no one alive today will see a mission that reaches the planet, and that's more accessible for most readers per above.
700 AU is way past heliopause, firmly in the interstellar space. Same, 15 times farther than Pluto is definitely away from the Solar system "proper". It's about 100 light-hours away from Sun.
I wonder how could this object be counted as a "planet" belonging to the Solar system, even if it were the size of Jupiter. But it's an object "estimated to be 2 to 4 times the radius, and about ten times the mass of the Earth". This must be another class of celestial bodies, some jumbo-sized Oort cloud object.
As long it is orbiting the sun, i.e bound by the solar gravitational field then it is in the solar system?
Also depending how elliptical the orbit, is the perigee might be much closer than 700AU, while still being further than Pluto's orbit. For all we know 700 AU is the apogee and say the perigee is 70 AU (1.4x Pluto's apogee ).
The body must also be large enough to clear other bodies in the same orbit, except at the Trojan positions (L4 and L5), to be considered as a planet. Otherwise it would just be a Trans-Neptunian Object (TNO) or a Kuiper Belt Object (KBO) at these distances.
It obviously does in this case. But this pedantic detail is rather important. It was used to demote Pluto a few years back.
Does it? Would we actually know if there was another slightly more sparse belt at 700AU? If we can't track a large planet in that area, why would we be certain about the belt?
Alternatively, if it's an external object captured by the Sun, how would we even classify it as clearing or not if there's nothing to clear?
I wanted to get a sense of what that MEANS relative to the rest of the gas giants. Apparently it’d be roughly the size of Uranus or Neptune.
I guess I’d always put all the gas giants in the same “very, unimaginably big” bucket. I knew Jupiter was the biggest, then Saturn, but I didn’t realize just HOW big they were compared to the rest. At the risk of stating the very, very obvious, Jupiter is huge!!!
Masses of gas giants are: Jupiter, 317.8 earth mass; Saturn, 95.2 earth mass; Neptune, 17.1 earth mass; Uranus, 14.5 earth mass
The rest of the planets are theorized to have condensed from the protoplanetary disk that formed the same molecular cloud the Sun did. I. e. they have formed at approximately same time as the sun and from same material, sans gravitational separation.
Would likely be older than the solar system itself. Probably not first gen star old, but likely would have formed before the sun did. Don't know how different it would be though. Would have formed out of maybe different ratios of elements than what was in the molecular cloud we formed from, but otherwise a large body like this would have undergone similar geological processes as our own planets.
The other planets formed from material in the same nebula (cloud of gas and dust) that collapsed to form the sun. The idea here is this planet would have been moving through the interstellar medium and just happened to pass close enough to the sun’s gravity well to get captured in a (very distant) orbit.
Capture would be like a reverse gravitational slingshot? This planet happened to meet the sun at an angle where it lost enough energy to fall into orbit instead of slinging back out like those comets that come around on long cycles?
It would be like a reverse gravitational slingshot, in a different way.
There is no way to capture with just 2 bodies - it would have to leave on gthe same hyperbolic orbit that it arrived on. However if it drove by and had a close enough interaction with a third body, like Jupiter, it could lose angular momentum to the planet, resulting in entering an orbit around the Sun. Further gravitational interactions with planets could then smooth that orbit out over time.
Alternately this could be the more straightforward scenario of interstellar object hits planetoid, they merge, and the new combined object is now in orbit.
AFAIK, it could be in a 2 bodies slingshot, multi-body interaction with some other stuff on the Oort cloud, or tidal interaction (what could happen way more easily with a nebula).
But a ball needs to lose energy to not roll right back up a hill to the same height it came from. And if that "ball" is a mass from outside our solar system, it will roll right back out of the solar system just as easily as it rolled in unless there is enough forces to slow it down enough to capture it.
Not true. An obit is not an infinite "plain" with a finite "hill" on but rather a finite "valley". The ball will exit the valley on the other side unless it loses excess kinetic energy somewhere in the valley.
Anything that approaches the sun will do so with faster than escape velocity because the gravitational potential energy gets converted into kinetic during the approach. Newtonian mechanics is time-reversible - just like it's impossible for an object in orbit to spontaneously escape without gaining energy from somewhere first, it's impossible to enter orbit without losing energy to another body.
Small nit: this is for objects approaching from infinity in a two body system. Otherwise the object can be in orbit and already be “captured” there. For example, the moon also approaches earth slightly over the month while speeding up, then slows down while moving away. Or it could just be a 3 body system, which is chaotic and can’t be modeled accurately and can have objects spontaneously eject from the stable system (even though the physics is indeed reversible)
Your first nitpick only makes sense with a weird definition of "approaches" for the context, so I think it just adds confusion. They're pretty clearly talking about something that is headed in the direction of the sun and not already in orbit.
And the comment you're responding to already mentioned that other bodies can make a capture happen. Nobody was saying capture is impossible.
That is not true. If it approaches with less than escape velocity it will gain all the velocity necessary to escape in the process of approaching the Sun.
You could think of it as speeding up as it falls toward the sun, it then slows down by the exact same amount as it leaves the Sun.
In order to stay near the sun it needs to lose some of that speed, and given that momentum is conserved, the only possible way is to either hit the Sun or send that momentum to a third object.
Would this be far enough out to use the sun's gravitational lensing to image distant planets?
It seems like the idea was to send a bunch of instruments way out and then take pictures in the brief time they were at a useful distance, but if there's a planet out there we can orbit and so stop the instruments at that distance it seems like we could make a permanent super telescope.
orbiting a planet in that case is no different than orbiting a sun on the same orbit as planet. Probably even more cumbersome, all that jiggling around. Or are you talking about making a gravity assist to turn the orbit of the probe into less eccentric?
Because more people know about Pluto than Eris or Sedna. And we know that Pluto is the furthest away planet (sue me). So 15x Pluto is much easier to visualize in context of the entire solar system than 700x Earth. My cosmological knowledge is above average, but I don't know off the top of my head if 700 AU is super-duper far away or still in the range of the gas giants.
> And we know that Pluto is the furthest away planet (sue me)
I don't need to sue you. It's just entirely incorrect by any sane definitions of a planet. It's not the further if you include similar bodies or not a planet. As I have no interest in saving American misplaced pride (because let's not kid ourself it's about anything else), I don't see the point of spreading misinformation.
> Because more people know about Pluto than Eris or Sedna
Only if you were born before it was retrograded which will be less and less likely as time goes on.
> My cosmological knowledge is above average, but I don't know off the top of my head if 700 AU is super-duper far away or still in the range of the gas giants.
I'm not convinced that giving it in multiple of the distance between Pluto and the sun is in any way more useful than distance between the Earth and the sun or that it helps conceptualise the distance relative to the gas giants.
Anyway, Pluto orbit is highly excentric so you have 20AU of wiggle room here when considering distance.
I know it's not a planet, hence my sarcastic "sue me". I suppose the self-irony didn't work too well over text. My point was that many people still know about Pluto as a body that's at the edge of many people's everyday conceptualizations of the solar system, and I argue that makes it a more useful tool for helping people intuitively understand the particular distances involved.
> Only if you were born before it was retrograded which will be less and less likely as time goes on.
I admit my age plays into it. Though I am curious about the role Pluto has in modern primary school, do you know? I understand that it now has the same technical status as Eris et al., but I think it's still a fantastic example of how scientific understanding develops and changes. Not on par with discarding heliocentricity, but a very practical example of ongoing changes still present in our own time.
> As I have no interest in saving American misplaced pride (because let's not kid ourself it's about anything else)
I don't understand how this ties into American pride (nor am I American), what did I miss?
Most readers probably know Pluto is the... well... it's not the farthest dwarf planet. But they know it's far, but don't realize just how far it is. I certainly didn't until I watched a video about it.
700 further from the Sun than Earth is tangible as "really really far" though.
I have a set of twelve books by an artist, titled "Astronomical" (one book for each letter). The first page shows the sun, then the rest of the books are almost all simply black pages, but with the planets and asteroid belt entities shown with accurate distance and size scale.
It communicates the scales really well, while only taking up a little over a foot of bookshelf space when not being "navigated". I have two heavy metallic retro looking rocket bookends for it.
My favorite: Cody'sLab's "How far away are the nearest stars": https://youtube.com/watch?v=dCSIXLIzhzk
Also gives an intuition for how incredibly bright stars shine
Yeah, when the solar system was introduced to my class in grade school, we had an outdoor excursion where the teacher brought out a golfball and place it at one end, then brought out various tiny things (noting scale was very approximate) and paced off each to show the relative distances.
I think both comparisons together paint a good picture: 15 times further than Pluto, which itself has an orbit ranging from 30 to 49 AU (the distance between Earth and the sun.)
I think both work. The average reader doesn't need to conceptualize these distances. They just need to know they're reallllly far away and realllllllly realllllllly (9x) far away. You can use the earth or pluto distances as relative scales.
It's sort of amazing to me that the Sun can capture objects that far away. Like obviously even at that distance the Sun would be by far the closest massive thing, but it's hard to comprehend the effects of gravity being strong enough at that distance. From "Planet 9" the Sun probably wouldn't significantly stand out from all the other stars in the sky, yet you'd be orbiting it.
Most people have at least a vague sense of Pluto being the edge of the solar system, so hearing that Planet Nine could be way beyond that makes it feel almost interstellar
I find one theory regarding Planet 9 especially interesting, and that is that it could be a primordial black hole with a Schwarzschild radius on the order of just a few centimeters. So basically, just a golf ball-sized black hole. This would explain why we can see the gravitational effects on the other objects as described in many papers, and it would also explain at the same time why we have no direct observation of this object, because it's simply too tiny and black.
It would be extremely difficult to observe something that far away from the sun, no matter how voluminous it is. I'm not going to scorn at the idea of a blackhole, but I wonder what process can crush that much mass into such a volume. I don't think it's massive enough to suffer a gravitational collapse.
Primordial black holes can theoretically be much smaller than those formed in the usual way from collapsed stars or neutron star mergers, etc, because the early universe was dense with matter already and perturbations could have caused gravitational collapses for arbitrary volumes. I don't think we've observed any directly, which would be hard as small low-emission masses. They're still a potential piece of the dark matter missing-mass puzzle.
Hawking radiation does not require an accretion disk.
Edit: with an accretion disk, I'd assume we'd have noticed it by now. Outside of that, as a black hole gets smaller, the hawking radiation wavelength should go down. It is rather weak overall, but it would be rather close. I haven't actually done the math, and, this is not my area of expertise. Would a relatively close by small black hole's hawking radiation be brighter than further X-ray emitters? Dunno.
The hawking radiation of a 9x earth mass is somewhere in the neighborhood of 0.01 K where the cosmic background is 2.7 K. It would appear to be a very tiny very cold ball.
The break even point for hawking radiation vs the cosmic background is about the mass of the moon.
I'm not going to do much more searching or calculation but I would be willing to bet a black hole small enough to emit xrays would have a remaining lifespan measured in nanoseconds at most.
A black hole bright enough to see its hawking radiation has to be tiny and would be quite short lived with an origin of unknown mechanism.
> A black hole bright enough to see its hawking radiation has to be tiny and would be quite short lived with an origin of unknown mechanism.
Depends on what distance you want to see it from.
A black hole that glows as hot as an incandescent filament would have as much mass as a 250km cube of rock and it would last for 10^35 years. It would have a radius of 60nm and emit less than a microwatt.
> a black hole small enough to emit xrays
To reach the low end of xrays, 100 electron volts, we'd need a black hole 100 times smaller. It would still have 10^29 years of lifetime, and would be emitting 2 milliwatts of xrays.
To reach the high end of xrays, 100k electron volts, we'd need a black hole 100k times smaller. It would still have 10^20 years of lifetime, and would be emitting 2 kilowatts of xrays.
To go the other way around, if I calculate a black hole that has "only" 10 billion years of lifetime left, weighing a dainty 190 million tons, it would be emitting 10 gigawatts of gamma rays. At 10 gigawatts of output, it would shrink by 1 ton every 285 years. The speed of light squared is an enormous number.
If I’m remembering right, compressing all of Earth’s mass would give a Schwarzschild radius of roughly 9 mm.
I think Uranus (15x heavier than earth) would be like basketball.
I really hope this is true, because it would mean there is a black hole close enough it could be examined and studied. This might allow us to test physics ideas that can’t be tested any other way, and maybe even to “finish” physics.
It could also allow gravity and Oberth effect acceleration of small probes to meaningful fractions of the speed of light for interstellar flyby missions. Imagine the Oberth effect boost from thrusting in such a deep gravity well.
I really hope it isn't true because if there's one out there, there will be others, and I'd rather not meet one in person.
We don't have enough data to see whether there are unexpected instabilities in detected planetary systems. But it would be an interesting project to look for those.
They're no more dangerous than a regular rogue planet, which are pretty common on a galactic scale. The gravitational effects (disruption to planetary orbits) are the same, and Earth would not meaningfully survive a collision with either.
I recall reading years ago some speculation that the Tunguska event may have been an encounter with such an object.
A micro black hole traveling at tremendous velocity would go right through the Earth and keep going, but as it encountered the atmosphere it might emit a bunch of ultra high energy gamma rays (due to accretion) that set off fusion reactions and create an airburst. From there it would shoot right through the Earth and cause another kaboom when it exited, but that would have been in the middle of the Pacific. Nobody would have noticed in 1908.
No way of knowing unless we find evidence in the form of a "track" through layers of rock or some other signature. A comet or other similar body remains a more likely explanation for that event.
They're not dangerous unless you get too close. A black hole is not a cosmic vacuum cleaner.
If the Moon were suddenly transformed into a tiny black hole with the same mass, it would continue to orbit the Earth at the same distance. Ocean tides due to its gravity would continue normally. There would not be much effect except that it would no longer be visible with the naked eye and would no longer reflect the sun's light back to Earth. If you found it in a telescope, you might see gravitational lensing as it passed in front of the star field. Objects like probes or old spacecraft stages orbiting the Moon would continue to do so.
The only danger would be that if things fell into it I suppose you might get dangerous X-ray and gamma ray emissions from its accretion disc that would be a problem at such a close range. That would not be an issue with a primordial black hole much further away.
If there were such an object we could send probes to orbit it and study it, and some experiments may involve firing objects or shooting lasers or beams of particles into it to attempt to learn about the quantum effects at the event horizon. This could be massive for physics, allowing us to access and observe conditions and energies not replicable here on Earth with any current technology.
BTW we don't have any hard evidence that primordial black holes exist, but many theories predict them. So far such predictions around black holes have a pretty good track record. If you made me bet, I would bet on them existing. They are a candidate for some or perhaps even all of dark matter, though even if that's not the case they might still exist. It's possible that the dark matter haloes we can spot with gravitational lensing are clouds of these things. ("Clouds" of course is a misnomer-- the distance between them would be many light years.)
If planet nine is a PBH it means that at some point one was captured by our solar system into a Kuiper Belt orbit. Even if planet nine isn't one, there still may be small asteroid mass PBHs in our solar system, so we still might find one. They would require extremely sensitive X-ray or gamma ray telescopes or highly accurate gravitational models of the solar system to detect.
It’s an object with theoretical maximum density. That’s one way to think about it.
Another visualization: if you had an Earth mass black hole with a solid shell surrounding it at the same radius as the Earth’s surface is from its core, gravity atop that shell would be 1g. The actual black hole would be about the size of a marble.
If you got close to it you would of course be subject to insane gravity and be “spaghettified” etc. All the mass would be in that marble. But at a distance it would be the same.
Compared to that object the Earth is mostly empty space. Ordinary matter is not that dense.
Black holes are totally fascinating. They are in some ways the most extreme objects that can possibly exist. If we could study one we could learn a lot.
For all it's worth, there's no need to go black hole to explain the lack of visual observation. Objects that far from a star reflect very little if any light and would appear black to a black background.
> If a black hole with a mass of, say, Ceres hit the Earth, it would not be particularly worse than if Ceres hit the Earth.
This equivalency is true for many aspects of orbital mechanics (depending on setup giving sufficient distance), but I don't believe that's true at all for a collision. Someone with more knowledge correct me, but a black hole with the mass of Ceres would be very tiny but also emitting a ton of radiation. The collision would be very different.
I more mean that the resulting moon-sized fragments of what used to be the earth would be equally devoid of life. I agree the physics might vary somewhat.
If the black hole had a mass more similar to a 0.5-mile asteroid...well, I'm not sure what would happen. Would it just punch a hole straight through the earth?
Honestly, if there is a golf ball–sized black hole out there chilling in the outer solar system, I'm all in.
Let’s fire up a replica of TARS, load up ChatGPT inside (TARS-GPT, patent pending), and yeet it straight toward the Schwarzschild golf ball. It’ll narrate live.
Imagine the livestream:
“Approaching event horizon. Spaghettification at 3%. Mood: stretchy.”
“Entering gravitational lensing zone… wow, even my tokens are redshifting.”
Bonus: With the right timing and Oberth maneuver, TARS-GPT might sling itself into Alpha Centauri before we finish arguing whether Pluto’s a planet again.
Worst case: we lose a robot.
Best case: we unlock quantum gravity and get a podcast from inside a black hole.
Not sure why the downvotes—if I came off wrong, my apologies. I genuinely meant it in a humoristic way. I'd honestly love to see a probe launched into a black hole.
Humor devolves the site into useless one liners. If you want evidence of that, go to reddit and see how useful that site is these days if you want to actually research and learn something. Slashdot knew this back in the day and while funny posts got visibility, they did not add anything to a user's total karma score.
Oh this site does humor great, it's just that the serious participants are so "focused" they don't (or can't) realize how funny their often esoteric comments are.
As far as devolving into useless one liners --there is an emerging tech called the at-proto (not related to modems hahaa) that is poised to disrupt billions of dollars worth of sites like this one. Enjoy this era while it lasts..
Politics is mostly soft-banned (downvoted to oblivion) for a similar reason. Most political discourse online devolves into rage bait and outrage porn and people regurgitating canned talking points.
Look at Xhitter for endless examples of this, basically the whole site now.
Yeah but you can't raise trillions of dollars with that. Investors want to be able to tell to their friends at parties that they helped made blackhole tech possible.
Not at that distance but black hole starship drives are theoretically possible. Far, far beyond our capabilities but possible within known physics. This is like Kardashev type II civilization stuff.
Domesticating fusion would be much easier. That is within sight.
A golf ball–sized primordial black hole lurking in the outer solar system sounds like pure sci-fi, but it would neatly explain the gravitational weirdness and the lack of visual detection
FWIW, the object in the linked article is visible, so while that's an interesting theory it's actually ruled out if this thing turns out to be a planet. The black hole would need to be Planet 10 I guess.
At the distances described, available passive light flux is so low, it could be 100% painted with white titanium dioxide paint and we’d be lucky to ever see it. It doesn’t need to be a black hole to be effectively invisible.
Indeed, it's a doubly inverse-squared law: one 1/d^2 factor for how far it is from the sun, by how much the solar flux is reduced; and one 1/d^2 factor again for how it is from Earth-based observers. 1/d^4, a quartic law.
That's the idea behind this paper (and similar ones like it): since they're looking for the planet's intrinsic emissions, from its internal heat, it's only a single inverse-square law.
With d being ~20 times Neptune's distance and ~140 times Jupiter's, these really are large factors!
Any chance we could use this black hole as a really powerful slingshot by getting very close right before passing the event horizon and then firing off into space?
I think one problem for such tiny black holes is the way the gravitation works on objects that come close to it. So for instance, a spaceship could or a human could not reach the event horizon of a tiny black hole in one piece, because it would be torn apart by the gravitational tides. So the question is how close can you come to the event horizon before gravitation rips you apart. My guesstimation would be not close enough to reach a meaningful percentage of c.
700 times further => isn't it farther rather than further?
Non native english speaker here, but last I checked further was a metaphorical distance, when farther was a literal distance. You can push a concept further, but you walk farther right? Or did I miss something?
If those two spots are the same object, that object is on a high-inclination orbit; but the pattern the Planet 9 hypothesis explains is only compatible with a low-inclination object.
Isn't this exactly how Pluto was discovered? Due to an innacurate estimate of the mass of Neptune (not corrected until Voyager I think), people were hunting for a large planet to explain the discrepancy. After a bunch of searching they happened to find Pluto, but it was not the Planet X they were looking for. The mass estimates for Pluto were gradually downgraded from many Earth masses to 1/500, which is the true reason it was initially classified as a planet.
Yeah. If Pluto had been slightly heavier, we’d probably have ended up with a definition of a planet that included its mass instead of clearing its orbit to keep Pluto a planet. But Pluto was cooked when we figured out it’s not really heavier than Ceres.
For a time pluto had good estimates for his small size, but poor constraints on his mass beyond this Neptune mass estimate. So I remember reading a short story were they interpreted the possible high density as signs of a stargate.
Back in the early 1800s children used to memorize the names of the 12 planets: Mercury, Venus, Earth, Ceres, Pallas, Juno, Vesta, Mars, Jupiter, Saturn, Uranus, and Neptune. But then in 1845 astronomers discovered Astraea, and now there were 13. In 1847 three more were discovered: Hebe, Iris, and Flora. Then Metis, Hygiea, Parthenope, and Victoria by 1850. The 100th asteroid was discovered in 1868, and the pace only got quicker from there. Somewhere along that line people started using the words “asteroid” and “asteroid belt” and schoolchildren were mercifully spared the pointless task of memorizing hundreds, and later many thousands, of names of asteroids.
The same thing happened to Pluto. Just as Ceres was the first discovered asteroid, Pluto was the first discovered TNO. There are now hundreds of named TNO and thousands more that are just numbered. Nobody should force schoolchildren to memorize them all. Just tell them that there are an unknown number of objects in the Kuiper belt and the Oort cloud and they’ll know as much as they need to know. Give them bonus points if they know the names Ceres and Pluto, and more if they know why these two were discovered first of all the objects in their class: they’re the biggest. Otherwise there’s nothing special about them.
> Nobody should force schoolchildren to memorize them all. Just tell them that there are an unknown number of objects in the Kuiper belt and the Oort cloud and they’ll know as much as they need to know.
Or just tell them that there's an unknown number of planets in the solar system, but the big 8 are the only ones they're expected to memorize. That was actually the original plan by the IAU, and how many (I believe most) planetary scientists define planet today.
The decision being based mainly on not wanting to add newly discovered planets to the list of planets in the solar system always rubbed me the wrong way. As is the tendency for people to mistakenly believe that this is settled science, when it's actually an unsettled nomenclature debate.
His team discovered Eris and many other trans-neptunian objects, which did fuel the discussion behind pluto's demotion: greatly increase the number of planets, or demote pluto? They're also behind the Planet 9 theory that's discussed in the article.
Perhaps searching for Planet 9 we went straight to Planet 10. There was another one and we happened to find it first. Or also it could be a nomadic planet undergoing a close encounter with the solar system.
is such a excentric orbitting body not like a giant guitar string when it comes to the gravitational influence of "passing bye" solar systems and black holes?
Not only would it be insanely cool, it'd give us a once-in-a-lifetime chance to study something that might've formed in the first moments of the universe
If you're interested in creating time dilation, then a planetary mass black hole unfortunately won't get you any further than, well, a regular planet with the same mass.
(Aside: time dilation already occurs on and around Earth. GPS satellites have to account for the fact that time runs ever so slightly slower on the ground.)
I don't think that's right except at a radius of a typical planet. At the event horizon of even a planetary mass black hole, gravity is so strong that light cant escape, and the time dilation effect should be the same as for any event horizon.
So, it’s not the local strength of the gravitational field, but the overall mass that matters? How does that work? I mean, if distance/ intensity doesn’t matter, than distance is irrelevant? That seems extremely counterintuitive.
I thought that since you could get into areas where the field was arbitrarily intense, that it would be able to provoke significant relativistic effects.
I had assumed that the small mass would make tidal forces more problematic than with a larger one, but if the distance/intensity of the field isn’t a factor, but only the overall mass… wouldn’t that mean that we could utilize black holes at arbitrarily long distance to provoke those effects, so it would just be a universal constant based on the mass of the universe, and there would be no relativistic effects on a relative basis?
The article explains that Planet X is a possible explanation for the apparent regularity of mass extinction events. Planet 9 is a separate concept to explain the bunching of Kuiper Belt objects, like Sedna.
In other words, PlanetX was a hypothetical rogue planet that appeared unexpectedly from the abyss of deep space and ambushed the unsuspecting Earth every once in a while. It has a dormamu vibe. I see why the scientists didn't like it.
love how nerdy this whole thread gets - so much hot debate for basically a frozen rock way out there. you think we're ever gonna agree on what counts as a planet or is it always just moving goalposts?
I can clearly see the object as a bright group of pixels in the IRAS image, but I don't see a damn thing at the spot they hilight in the AKARI image. Like, are they kidding or is this a crap article with the wrong image or something?
You'd have to read the actual paper [1] to understand this. It does not appear as a physical source in the plot because of how the dataset works. The image is only for reference regarding the position.
It has everything to do with the available means that we have, for now. For the record though, we haven't yet been able to spot planets in other galaxies, just in our own Milky Way. The spotted ones just happened to be there when we decided to look, twice. To spot an astral body properly sized to fit the definition of planet, which we yet suspect to orbit around our own star, we should be lucky enough to look exactly at it and not at something else.
we already have a 9'th planet, but due to the greatest pedantic campain of all time, pluto got demoted. Though given the current situation, ha!, that could change.....perhaps the naming commity will get noticed, and be offered a chance to do a deal, and Make Pluto A Planet Again,(MPAPA)
We should add those planets to the official list too. Gauss considered Ceres to be a planet and I believe him over living astronomers.
The motivation for this dwarf planet nonsense was to try to keep the official planet list small so children could memorize them with ease, but that is absurd. We do not remove countries from the map to make it easier for children to learn geography and there are over 100 of them.
For a generation, schoolchildren everywhere memorized the names of the 12 planets: Mercury, Venus, Earth, Ceres, Pallas, Vesta, Juno, Mars, Jupiter, Saturn, Uranus, and Neptune.
The list was stable at 12 for about 40 years, but started growing again in the middle of the century. By 1868 there were 100 named asteroids. Not a single one has people living on it, so making children memorize their names was seen as a waste of time. Teach them about the asteroid belt and then move on to more important things. Likewise with the TNO: teach them about the Kuiper belt and the Oort cloud and then move on to more important things. No need to make them memorize Pluto, Haumea, Makemake, Gonggong, Quaoar, Sedna, and Orcus, nor any of the hundreds of other named TNO.
Remelting whole planet is such a nonsense, it would take millions of years for the large body as Mars to cool enough for surface to be usable.
By the way, the loss of atmosphere takes millions of years too. The popular "we must restart mars magnetic field" trope likes to omit the fact. In the end occassional replenishment of volatiles would probably be cheaper.
If planets are required to clear their orbits, what was Jupiter called while the solar system was forming? A dwarf planet? A proto planet? The entire time?
Was earth not a planet shortly before and after collision with Theia?
The naming pedantry seems ridiculous given that we have such a small sample size.
Every single definition that segments a real world set of continuous objects into discrete buckets has surprising edge cases. This is basically inescapable.
To steal a quote: All definitions are wrong. Some are useful.
I find that to be the most weird one too. I don't know much about orbital mechanics but in the unlikely chance 2 bodies shared an orbit does that mean they aren't planets then? How close can two planets be before losing that designation? I share your ire.
> If planets are required to clear their orbits, what was Jupiter called while the solar system was forming?
Hell, what's it called now? Jupiter's orbit is shared with millions of Trojans. Many of them are more than a hundred kilometers in diameter; for reference, Deimos, one of Mars' moons, has a mean radius of about 6 km.
Back in the day Mercury, Venus, Earth, Ceres, Pallas, Vesta, Juno, Mars, Jupiter, Saturn, Uranus, and Neptune were the 12 planets. You could kinda consider Pluto to be the 13th planet, but in 1930 when it was discovered there were already over 1000 named asteroids. So Pluto is the 1146th planet.
Pallas and Vesta aren't gravitationally rounded, though. But then again, the Moon is (being much larger than Ceres). (It's just better numbered as planet 3-1.)
The definition is pretty arbitrary. It's more interesting, what can we learn by studying that object. Even the trivia, like tidal locking, it was one of my 10000 moments (https://xkcd.com/1053/).
Any such ship is going to grow its own food. They may need to carry some extra matter to compensate for accidentally or inevitably lost biomatter. But otherwise they would be able to recycle the same biomatter repeatedly to create food. The only limiting factor is energy. You'll need to add energy in every cycle. Recycling isn't going to happen for it.
Of course, all of this comes with the caveat that nothing like this may exist yet. Sealed mass ecosystems exist in glass jars, but something on the scale of a ship is going to be an entirely different ballgame.
Please don't complain about tangential annoyances—e.g. article or website formats, name collisions, or back-button breakage. They're too common to be interesting.
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