An Earth-sized rogue planet discovered in the Milky Way(phys.org)
phys.org
An Earth-sized rogue planet discovered in the Milky Way
https://phys.org/news/2020-10-earth-sized-rogue-planet-milky.html
108 comments
It's fascinating how fascinated we are with categories, typologies and their exceptions. It's like Sapiens crack, especially nerd sapiens.
Here is is our linnaean classification of species. Look how these species are breaking the species barrier!
Nature, meanwhile, isn't very fussy about the concept of species. It's not even strict about the concept of an organism.. even cells or any of the classifications we use to understand bundles of biology.
A planet is a thing that orbits our sun. Hey, exoplanets! A planet is a thing that orbits a star. Hey, rogue planets. Hey, rogue solar system! Meanwhile, the universe isn't all that fussy about solar systems or galaxies.
Here is is our linnaean classification of species. Look how these species are breaking the species barrier!
Nature, meanwhile, isn't very fussy about the concept of species. It's not even strict about the concept of an organism.. even cells or any of the classifications we use to understand bundles of biology.
A planet is a thing that orbits our sun. Hey, exoplanets! A planet is a thing that orbits a star. Hey, rogue planets. Hey, rogue solar system! Meanwhile, the universe isn't all that fussy about solar systems or galaxies.
I've recently become kind of obsessive on experimenting with this and our natural inclination to adopt and find patterns, habits, categorization. I've been tinkering with various ways to optimize it, seeing how I best adopt new habits or learn new things (right now it's full immersion with small breaks, like hiit but for your brain). You really start to realize that almost all knowledge is just implicitly some sort of massive memory map and association.
I think the most interesting stuff is how things work. How do they form, what’s their life cycle, what attributes and effects to they have, etc. But classifying things is useful to understand the processes and attributes they have in common. But yes our classifications are just a map, and we should not confuse the map for the terrain.
Can we avoid confusing map with terrain?
Our minds don't seem to naturally make as much of a distinction between abstraction and manifestation as we do.
Our minds don't seem to naturally make as much of a distinction between abstraction and manifestation as we do.
Who is "our minds" vs "we"?
The question of existence.
A human being is spirit. But what is spirit? Spirit is the self. But what is the self? The self is a relation that relates itself to itself or is the relation's relating itself to itself in the relation; the self is not the relation but is the relation's relating itself to itself. A human being is a synthesis of the infinite and the finite, of the temporal and the eternal, of freedom and necessity, in short, a synthesis. A synthesis is a relation between two. Considered in this way a human being is still not a self. In the relation between two, the relation is the third as a negative unity, and the two relate to the relation and in the relation to the relation; thus under the qualification of the psychical the relation between the psychical and the physical is a relation. If, however, the relation relates itself to itself, this relation is the positive third, and this is the self. -Søren Kierkegaard, "The Sickness Unto Death"
You can, but it requires higher cognitive reasoning. Almost a meta-understanding of understanding. Which starts with self awareness and understanding of categories and taxonomies, what they are, who defines them, that there exist more than one, and that they are just models that serve practical needs.
That said, it isn't always easy, I feel like it was only 5 years ago I started to realize this myself as I got more interested in models, categories and taxonomies. And I feel this is a common mistake people make prior to being experts themselves (in any field), is confusing the abstraction for the concrete.
A very simple example is how tomatoes are both fruits and veggies, in reality, tomatoes are tomatoes, but in culinary science, it is more useful to consider a tomato a vegetable, because most recipes that call for fruits wouldn't be good with tomatoes in them. On the other hand, in botanical science, it is categorized a fruit, as fruit describes the category of seed-bearing structures in flowering plants.
This shows how various studies will use different models, categories and taxonomies to work with that is best adapted for their end results.
The beauty of such models is that they can help innovation, by allowing us to reason about more than we can at once. That's the benefit of any abstraction. But in doing so, we also reduce reality to a simplification, albeit one that ideally allows us to figure out something which meets our requirements and provide us the practical benefits we were looking for, like say figuring out how to build a machine that can fly.
So my advice would be to stop arguing semantics, because so often people will debate what is what: "no tomatoes arn't fruit that's ridiculous they are vegetable". Well who cares, they are what works best, and if you're baking, its better to consider them a vegetable, but if you're gardening, you'll be better considering them fruits. So instead start arguing about the models, it's better they be fruits when gardening because of x,y,z practical reasons that apply to gardening.
That said, it isn't always easy, I feel like it was only 5 years ago I started to realize this myself as I got more interested in models, categories and taxonomies. And I feel this is a common mistake people make prior to being experts themselves (in any field), is confusing the abstraction for the concrete.
A very simple example is how tomatoes are both fruits and veggies, in reality, tomatoes are tomatoes, but in culinary science, it is more useful to consider a tomato a vegetable, because most recipes that call for fruits wouldn't be good with tomatoes in them. On the other hand, in botanical science, it is categorized a fruit, as fruit describes the category of seed-bearing structures in flowering plants.
This shows how various studies will use different models, categories and taxonomies to work with that is best adapted for their end results.
The beauty of such models is that they can help innovation, by allowing us to reason about more than we can at once. That's the benefit of any abstraction. But in doing so, we also reduce reality to a simplification, albeit one that ideally allows us to figure out something which meets our requirements and provide us the practical benefits we were looking for, like say figuring out how to build a machine that can fly.
So my advice would be to stop arguing semantics, because so often people will debate what is what: "no tomatoes arn't fruit that's ridiculous they are vegetable". Well who cares, they are what works best, and if you're baking, its better to consider them a vegetable, but if you're gardening, you'll be better considering them fruits. So instead start arguing about the models, it's better they be fruits when gardening because of x,y,z practical reasons that apply to gardening.
I agree that navigating the ambiguity between different categories requires thinking meta. Where I disagree is the need to drop semantics. Semantics are the foundation of how we organize our society. Perhaps on a small-scale or a personal level, dropping categories can be helpful, even freeing. For that to be done universally would be a disaster. I can see that being possible in the future, after large-scale social change, but not currently. The bulk of modern political discourse is effectively arguments over definitions of various categories and the membership of their constituencies.
Even something as minor as the category of a tomato, would matter very much to a tomato farmer when, hypothetically, all vegetable farms qualify for a higher level of government subsidies than fruit farms. Or to a retailer when, again hypothetically, fruits and vegetables are charged different sales tax rates.
Even something as minor as the category of a tomato, would matter very much to a tomato farmer when, hypothetically, all vegetable farms qualify for a higher level of government subsidies than fruit farms. Or to a retailer when, again hypothetically, fruits and vegetables are charged different sales tax rates.
Your example only reinforces GP's point. Arguing semantics and confusing map for territory only wastes everyone's time and effort. It's a trap, and we won't progress as society to handle tough political problems until we learn to stop doing it.
What the farmer in your example cares about is the legal classification of tomatoes in context of subsidies and taxation. That's an entirely different thing that biological, or culinary classification, and needs to be explicitly separated. If it isn't it leads to idiocy.
Real life examples of such inane reasoning can be seen with some very popular complaints about "stupid EU bureaucracy" - for example, that EU "decided that snails are fish" (they aren't, they just get bucketed with fish for some trade deal). People really do use it as a serious argument.
What the farmer in your example cares about is the legal classification of tomatoes in context of subsidies and taxation. That's an entirely different thing that biological, or culinary classification, and needs to be explicitly separated. If it isn't it leads to idiocy.
Real life examples of such inane reasoning can be seen with some very popular complaints about "stupid EU bureaucracy" - for example, that EU "decided that snails are fish" (they aren't, they just get bucketed with fish for some trade deal). People really do use it as a serious argument.
You're assuming that we can distinguish between map and territory and science is definitively proving we cannot. See Dr. Robert Sapolsky on behavior as an example.[1] And philosophers like Kant speculate it's map all the way down, so to speak. That perspective is very compatible with everything we know about the world and ourselves. You'll need extraordinary evidence to prove you have a handle on what territory is. Because at this juncture pointing to anything as territory is an extraordinary claim.
And sure, instead of legal classifications, one can discuss ethics related examples. Such as what makes for the good life? Something as simple as saying, the good life is based on some common sense notion of good or the good life is different for everyone and dependent on unique personal circumstances, already assigns numerous categories implicitly. That doesn't mean that both of those notions of the good life cannot be right. It does mean that we need categories to discuss and reconcile their differences, if we wish to have a pluralistic and liberal [in the 19th century sense of the word] society.
[1]https://www.indiebound.org/book/9781594205071
And sure, instead of legal classifications, one can discuss ethics related examples. Such as what makes for the good life? Something as simple as saying, the good life is based on some common sense notion of good or the good life is different for everyone and dependent on unique personal circumstances, already assigns numerous categories implicitly. That doesn't mean that both of those notions of the good life cannot be right. It does mean that we need categories to discuss and reconcile their differences, if we wish to have a pluralistic and liberal [in the 19th century sense of the word] society.
[1]https://www.indiebound.org/book/9781594205071
> Physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods of ordering and surveying human experience.
> In this respect our task must be to account for such experience in a manner independent of individual subjective judgement and therefore objective in the sense that it can be unambiguously communicated in ordinary human language. "The Unity of Human Knowledge" (October 1960) Niels Bohr
> In this respect our task must be to account for such experience in a manner independent of individual subjective judgement and therefore objective in the sense that it can be unambiguously communicated in ordinary human language. "The Unity of Human Knowledge" (October 1960) Niels Bohr
In fairness to sapiens, the patterns are everywhere we’ve looked, even when we look at things 100,000 times smaller or 100,000 times bigger than anything that any of our Earthly peers have.
The classification is done because rogue planets etc. tell us things about the process of solar system and planetary formation. Yeah nature tends to have a continuum of things, but the classifications are primarily used as place holders so that people know what everyone's talking about.
Since stars form in explosive events, it seems painfully obvious that some of the shit that comes flying out does not stick around, and that it could be planet sized/shaped.
Stars are formed in nebulas of gas and dust via gravitational collapse (accretion).
The remaining gas and dust that is swirling around the star flattens out into a disk (because of angular momentum). Planets gradually form in this disk, again via accretion (snowball effect).
https://en.m.wikipedia.org/wiki/Protoplanetary_disk
https://en.m.wikipedia.org/wiki/Accretion_(astrophysics)
The remaining gas and dust that is swirling around the star flattens out into a disk (because of angular momentum). Planets gradually form in this disk, again via accretion (snowball effect).
https://en.m.wikipedia.org/wiki/Protoplanetary_disk
https://en.m.wikipedia.org/wiki/Accretion_(astrophysics)
There are often clear boundaries or transitions between many natural things that aren't just "made up" for the purpose of satisfying us.
How do you think we would understand anything without categorisation?
The periodic table comes to mind.
Exceptions to the rule are the thing that drive new science.
It isn't Eureka we're looking for its, huh, thats funny.
The periodic table comes to mind.
Exceptions to the rule are the thing that drive new science.
It isn't Eureka we're looking for its, huh, thats funny.
Hopefully we'll find one day that Nature isn't fussy with the speed of light.
It's the exceptions that teach you something new and further your understanding.
It isn’t just about arbitrary classifications and their exceptions in this case. Rogue planets must have formed inside sone solar system, and somehow been ejected. This is interesting.
Language is a system of categories. Our limited minds are only able to approach approximations.
The last 20 years have been a remarkable time in astronomy. The rate of new discoveries are unparalleled.
Thinking one step further: Can a galaxy escape from a cluster?
Kurzesagt has an interesting video on life on rogue planets, https://www.youtube.com/watch?v=M7CkdB5z9PY.
Wait a minute, the article says there’s no star within 8 AU? That doesn’t necessarily mean it’s a rogue planet, it could have a host star at 9 AU, the distance of Saturn from the Sun. What an I missing?
I didn't read the paper, but if they can measure its orbital eccentricity, they can see if it's gravitationally bound to that star. Like they did with ʻOumuamua.
Assuming we never crack FTL travel, I suspect rogue planets/planetoids will be part of our strategy to travel between the stars.
To what purpose though? If you can steer a mass as big as a Earth sized planet then you might as well build a custom rig with all the trappings of First Class travel.
Otherwise you are just a Hobo jumping on a passing train and hoping it ends up somewhere hospitable so that your great great great great great ... great... great... great... great grandchild, an lineage born and lived entirely on the train, has a place to call home.
Otherwise you are just a Hobo jumping on a passing train and hoping it ends up somewhere hospitable so that your great great great great great ... great... great... great... great grandchild, an lineage born and lived entirely on the train, has a place to call home.
Depending on the tech, some mix of refueling station, colony or yeah passing train.
Without FTL, to spread over the galaxy we'll need to adjust our thinking on long time-scales for any of it to make sense or be possible anyway. We'll be a different species really (or _several_ different species).
If I were to bet, I'd say our more lasting contribution to the galaxy will more likely be mechanical (AI) descendants rather than ourselves, and next most likely would be barely recognizable biological dscendants (not necessarily that different from us physically, but in terms of society and mentality). That's all assuming we make it off of Earth and then away from Sol at all in any lasting way.
Without FTL, to spread over the galaxy we'll need to adjust our thinking on long time-scales for any of it to make sense or be possible anyway. We'll be a different species really (or _several_ different species).
If I were to bet, I'd say our more lasting contribution to the galaxy will more likely be mechanical (AI) descendants rather than ourselves, and next most likely would be barely recognizable biological dscendants (not necessarily that different from us physically, but in terms of society and mentality). That's all assuming we make it off of Earth and then away from Sol at all in any lasting way.
I think it's more likely that we "cure" aging and senescence than invent FTL.
If you can live for 10,000 or 100,000 years then being limited to lightspeed isn't such a bummer. You can visit interesting places.
If you can live for 10,000 or 100,000 years then being limited to lightspeed isn't such a bummer. You can visit interesting places.
That does seem like a good bet. Humans that can live tens of thousands of years would probably have to have a completely different view of time and the universe, and may have a better shot of seeing the stars too.
Being organic is the biggest drawback. Being individuals is the second biggest.
If the AI doesn't absorb us somehow, I suspect it'll limit our ability to contaminate the rest of the galaxy.
If the AI doesn't absorb us somehow, I suspect it'll limit our ability to contaminate the rest of the galaxy.
That's my theory too: to an AI information is food, and the densest source of information in the Universe is us.
(In the infosphere the Earth shines alone in darkness, the sole star.)
The machine will keep us in a bottle to feed off of our data.
...
Come to think of it, why wouldn't it "farm" us over a larger volume?
(In the infosphere the Earth shines alone in darkness, the sole star.)
The machine will keep us in a bottle to feed off of our data.
...
Come to think of it, why wouldn't it "farm" us over a larger volume?
I don't see how humanity is a source for information beyond the initial growth phase (assuming it's created here on Earth).
If an AI comes from space, it's likely billions of years old and we are as interesting as fungus.
If an AI comes from space, it's likely billions of years old and we are as interesting as fungus.
Well, Information is defined as the unpredictability of a message, eh?
> I don't see how humanity is a source for information beyond the initial growth phase (assuming it's created here on Earth).
Setting aside the possibility that Earth life is already an ancient alien nanotech AI ( https://en.wikipedia.org/wiki/Panspermia ), and assuming that humans are unique in the Universe, the rest of the entire Universe is pretty much predictable. There may be some poetic physics going on out there (I mean, of course there is, the Universe is beautiful!) but unless there's another planet of insane ape-men out there somewhere ours is the only show in town.
> I don't see how humanity is a source for information beyond the initial growth phase (assuming it's created here on Earth).
Setting aside the possibility that Earth life is already an ancient alien nanotech AI ( https://en.wikipedia.org/wiki/Panspermia ), and assuming that humans are unique in the Universe, the rest of the entire Universe is pretty much predictable. There may be some poetic physics going on out there (I mean, of course there is, the Universe is beautiful!) but unless there's another planet of insane ape-men out there somewhere ours is the only show in town.
We're going to have to cure boredom too. Just a few months in my apartment because of COVID and I'm already about to crack. How long does it take to update Netflix at 1000 light years?
If you can get close to light speed you can go 1000 light years in ~6 months of ship time.
https://www.fourmilab.ch/cship/flythru.html
You'd have hundreds of years of media to catch up on when you got back.
https://www.fourmilab.ch/cship/flythru.html
You'd have hundreds of years of media to catch up on when you got back.
An artificial intelligence would have no issue with a galactic colonization project taking 100 million years.
I imagine that the limitations of organic lifespan limitations will disappear with our species.
The most we can hope for is that AI somehow takes us with it.
I imagine that the limitations of organic lifespan limitations will disappear with our species.
The most we can hope for is that AI somehow takes us with it.
We could leave chunks behind as railway stations.
IF we can and should spread from our solar system, we're going to have to do that, and many many expeditions will have to fail and die. Just like the trillions of our ancestors' competitors that were not fit to survive.
Everything we do is survivorship bias. On Earth we may be the gardeners, but in space we're just the seeds.
Everything we do is survivorship bias. On Earth we may be the gardeners, but in space we're just the seeds.
Finding and tracking these rogue planets today seems to be a bit like the astronomers of old figuring out the movement of planets in our solar system. It'll probably be very useful in the future. Maybe one day we might even be able to adjust the course of one of them.
Related to this, I wonder what the minimum resources a rogue planet has to have for human habitation in the future. Obviously there won't be sunlight, which means that we will have to generate all of our energy in some other way. Nuclear fission? Fusion?
Related to this, I wonder what the minimum resources a rogue planet has to have for human habitation in the future. Obviously there won't be sunlight, which means that we will have to generate all of our energy in some other way. Nuclear fission? Fusion?
There is geothermal energy if it has a molten core.
Maybe chemical energy also. Think in a planet with a sea of methane for example.
Won't help much if there is not something else to react it with. I guess you could get the hydrogen from it and use it for fusion reactors.
Also if you find some water you could split it for oxygen and use methalox rocket propulsion locally.
Also if you find some water you could split it for oxygen and use methalox rocket propulsion locally.
Metal and silicon oxides can be cracked for the oxygen, either as a separate process or as part of consuming the methane. That might be enough to keep you from freezing to death.
Plants to consume the carbon dioxide, giving you calories and the oxygen back.
Plants to consume the carbon dioxide, giving you calories and the oxygen back.
This makes no sense. In order to land on such a planet you need to accelerate to its speed anyway.
The planet doesn't offer much to help the travel, yet you need to get out of its gravity well when you arrive.
The planet doesn't offer much to help the travel, yet you need to get out of its gravity well when you arrive.
If the planet happens to be going exactly where you’re going, that’s a problem for you in 100 years. Meanwhile you have a radiation shield covering nearly half of the sky, and if you actually land, free gravity.
I'm thinking the gravity would be too much, but it could be great for mining machines
I wonder if life would be possible on such a planet. It would need to generate its own heat, much like the earth does in its core. There could be small habitable zone much like the ecosystem near deep sea volcanoes.
The instant question this title raises: how hard would it be to move a planet into close orbit of the sun?
Weirdly enough I never came up to a similar scenario in countless sci-fi books. I'd imagine it would be so expensive that if we were capable of it we would probably wouldn't need/want it as other alternatives would be much more efficient, right?
The thought of designed solar system is interesting - what if we FTL is an unbeatable barrier - we might just be stuck here and populate our system with hundreds of rogue passerby planets!
Weirdly enough I never came up to a similar scenario in countless sci-fi books. I'd imagine it would be so expensive that if we were capable of it we would probably wouldn't need/want it as other alternatives would be much more efficient, right?
The thought of designed solar system is interesting - what if we FTL is an unbeatable barrier - we might just be stuck here and populate our system with hundreds of rogue passerby planets!
Aliens in Ring World do it: https://en.wikipedia.org/wiki/Pierson%27s_Puppeteers#Homewor...
Aside from the logistics and energy requirements of controlling the trajectory of something that weighs 10^24 kg, I wouldnt trust anyone alive on earth to be able to work out a stable orbit that wouldnt impact the delicate existing balance of our solar system. Something that massive would change the orbits of earth, mars, venus, even jupiter to a certain extent, not to mention all the asteroids and comets. The current stable configuration of the solar system was surely a significant contributor to the evolution of life, and it probably just came about as a freak accident. No way I would vote to allow anyone to mess with it on this scale.
Napkin math: Earth orbits at ~30 km/s, escape velocity is ~42 km/s. So to get Earth to leave the solar system (the inverse of capturing a planet under the most optimal circumstance), you would need to give it 12 km/s. Earth is ~6 * 10^24 kg, so that represents ~4.3 * 10^32 joules. The sun gives out around 3.8 * 10^26 joules per second (i.e. watts).
So with perfect efficiency, working just from conservation of energy, this would require around 13 days of the entire energy output of the sun. Or around a trillion years at Earth's current energy consumption.
So with perfect efficiency, working just from conservation of energy, this would require around 13 days of the entire energy output of the sun. Or around a trillion years at Earth's current energy consumption.
Napkin math, my favorite kind of math. Love the days of the sun output part. Sure why not...only 13 days.
Cool! For a Nice read on a Roque planet (fiction): https://georgerrmartin.com/grrm_book/dying-of-the-light/
How far is it? The article doesn't say.
The distance is unknown[1] and if it were very far away, it actually could be a Jupiter-sized planet - I believe there was other circumstantial evidence that suggested this didn't "move" like a gas giant. I am not sure what a "Gaia proper motion measurement of the source" means [this is from the article] but I am not an astronomer and didn't read the whole article.
Keep in mind how they detected this: they looked at the gravitational distortion of light caused by the planet's influence. We are used to seeing this gravitational lensing with black holes, which is visibly obvious even to an untrained human eye. The effect exists for every object with mass, but it's extremely tiny for planet-mass objects. For planet detection without a host star, it is the best measurement we have, but it's very finnicky and doesn't contain very much information compared to spectral analyses, motion around a host star, etc.
From that paper's abstract:
> Although in practice [rogue planets] do not emit any light, they may be detected using gravitational microlensing via their light-bending gravity. Microlensing events due to terrestrial-mass rogue planets are expected to have extremely small angular Einstein radii (~ 1 µas) and extremely short timescales (~ 0.1 day). Here, we present the discovery of the shortest-timescale microlensing event, OGLE-2016-BLG-1928, identified to date (tE ≈ 0.0288 day = 41.5 min). Thanks to the detection of finite-source effects in the light curve of the event, we were able to measure the angular Einstein radius of the lens θE = 0.842 ± 0.064 µas, making the event the most extreme short-timescale microlens discovered to date. Depending on its unknown distance, the lens may be a Mars- to Earth-mass object, with the former possibility favored by the Gaia proper motion measurement of the source. The planet may be orbiting a star but we rule out the presence of stellar companions up to the projected distance of ∼ 8.0 au from the planet. Our discovery demonstrates that terrestrial-mass free-floating planets can be detected and characterized using microlensing.
[1] https://arxiv.org/pdf/2009.12377.pdf
Keep in mind how they detected this: they looked at the gravitational distortion of light caused by the planet's influence. We are used to seeing this gravitational lensing with black holes, which is visibly obvious even to an untrained human eye. The effect exists for every object with mass, but it's extremely tiny for planet-mass objects. For planet detection without a host star, it is the best measurement we have, but it's very finnicky and doesn't contain very much information compared to spectral analyses, motion around a host star, etc.
From that paper's abstract:
> Although in practice [rogue planets] do not emit any light, they may be detected using gravitational microlensing via their light-bending gravity. Microlensing events due to terrestrial-mass rogue planets are expected to have extremely small angular Einstein radii (~ 1 µas) and extremely short timescales (~ 0.1 day). Here, we present the discovery of the shortest-timescale microlensing event, OGLE-2016-BLG-1928, identified to date (tE ≈ 0.0288 day = 41.5 min). Thanks to the detection of finite-source effects in the light curve of the event, we were able to measure the angular Einstein radius of the lens θE = 0.842 ± 0.064 µas, making the event the most extreme short-timescale microlens discovered to date. Depending on its unknown distance, the lens may be a Mars- to Earth-mass object, with the former possibility favored by the Gaia proper motion measurement of the source. The planet may be orbiting a star but we rule out the presence of stellar companions up to the projected distance of ∼ 8.0 au from the planet. Our discovery demonstrates that terrestrial-mass free-floating planets can be detected and characterized using microlensing.
[1] https://arxiv.org/pdf/2009.12377.pdf
AFAIU, the star being lensed was within the Milky Way, so they could establish some limits on the size of the lensing planet. The upper size bound in the paper is 2 earth masses.
(Jupiter mass does come up, but only in the context of a binary system - when ruling out that this planet is orbiting a star, they can only rule out a parent body larger than a few Jupiter masses.)
(Jupiter mass does come up, but only in the context of a binary system - when ruling out that this planet is orbiting a star, they can only rule out a parent body larger than a few Jupiter masses.)
Thanks, I see that in the paper now - I didn't get further than the abstract :)
The Founders
88840-8855(2)
Can they compose dark matter?
The matter we can see only accounts for ~4% of the 'stuff' that orbital mechanics says is there, and the other stuff doesn't interact with light (so no clouds)
There would have to be 25 times as many rogue planets as the mass of all systems, and most of the mass in a system is in its sun, so 25 Earths, Jupiters and Saturns are barely a blip.
There would have to be 25 times as many rogue planets as the mass of all systems, and most of the mass in a system is in its sun, so 25 Earths, Jupiters and Saturns are barely a blip.
4% of the 'stuff' is when we're considering dark energy, but I'm talking only about matter here (galaxy scale).
There's still more than 5 times more dark matter than any matter we see, though. But I thought if it's extremely hard to detect rogue planets, then what if there's whole bunch of them, like really 6 times more than other matter including stars. And there's no clouds around them for some reason (example reason is that they were expelled from their formation clouds by gravitation dance with other planets there).
There's still more than 5 times more dark matter than any matter we see, though. But I thought if it's extremely hard to detect rogue planets, then what if there's whole bunch of them, like really 6 times more than other matter including stars. And there's no clouds around them for some reason (example reason is that they were expelled from their formation clouds by gravitation dance with other planets there).
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That’s no planet...
> However, theories of planet formation and evolution predict the existence of free-floating (rogue) planets, gravitationally unattached to any star.
What's the theory that predicted this? After billions of years, I would expect all planets be attached (gravitationally) to a star, shouldn't they?
> Indeed, a few years ago, Polish astronomers from the OGLE team from the Astronomical Observatory of the University of Warsaw provided the first evidence for the existence of such planets in the Milky Way.
Wait. Evidence is not the theory. Did they predict this or discover it?
What's the theory that predicted this? After billions of years, I would expect all planets be attached (gravitationally) to a star, shouldn't they?
> Indeed, a few years ago, Polish astronomers from the OGLE team from the Astronomical Observatory of the University of Warsaw provided the first evidence for the existence of such planets in the Milky Way.
Wait. Evidence is not the theory. Did they predict this or discover it?
I don't quite understand why you're being so pedantic about this. The earliest reference I could find was from 1987, theorizing that proto-planetary objects could be ejected from a planetary disk and that this likely happened in our solar system due to sling-shotting from Jupiter[1]:
> After Jupiter had accreted large amounts of nebular gas, it could have gravitationally scattered the planetesimals remaining nearby into orbits which led to escape from the Solar System.
But this was purely speculative. It wasn't until many years later that the planet was actually observed.
> After billions of years, I would expect all planets be attached (gravitationally) to a star, shouldn't they?
I am not sure what you mean by that. All planets are formed in disks surrounding a star (or possibly a brown dwarf); rogue planets are planets that were able to escape the influence of that star. It might take billions of years before they get close enough to another star in the galaxy to fall into its influence.
[1] https://ntrs.nasa.gov/citations/19870013947
> After Jupiter had accreted large amounts of nebular gas, it could have gravitationally scattered the planetesimals remaining nearby into orbits which led to escape from the Solar System.
But this was purely speculative. It wasn't until many years later that the planet was actually observed.
> After billions of years, I would expect all planets be attached (gravitationally) to a star, shouldn't they?
I am not sure what you mean by that. All planets are formed in disks surrounding a star (or possibly a brown dwarf); rogue planets are planets that were able to escape the influence of that star. It might take billions of years before they get close enough to another star in the galaxy to fall into its influence.
[1] https://ntrs.nasa.gov/citations/19870013947
The comment came off stronger than intended. It sounded like lazy journalism that made a claim, but then used a different conclusion. Thank you fr pointing me to the NASA site.
> that were able to escape the influence of that star.
What's the mechanism here? Is it something with greater mass that pulled it into an escape?
> that were able to escape the influence of that star.
What's the mechanism here? Is it something with greater mass that pulled it into an escape?
>>that were able to escape the influence of that star.
>What's the mechanism here? Is it something with greater mass that pulled it into an escape?
I'm a layman. Take what I say with skepticism, but I think in this case the parent poster was referring to any mechanism that ends up with a planet getting out of the orbit of the star. One such potential mechanism is gravitational slingshotting.
Let's imagine you have a planet orbiting a star. A satellite flies in towards the planet. As the spacecraft passes by the planet, it gets some of the momentum of the planet as the planet is moving around the star. The planet loses that momentum. This increases the satellite's velocity in relation to the sun. The satellite can reach escape velocity and escape the influence of the star.
Edit: alternatively to reading my explanation, you could read Wikipedia's: https://en.wikipedia.org/wiki/Gravity_assist#Explanation
There's an amazing gif of Voyager 2's slingshots. Pay attention to the velocity as it passes planets: https://en.wikipedia.org/wiki/Gravity_assist#/media/File:Ani...
I don't see why a similar thing couldn't happen to planets.
>What's the mechanism here? Is it something with greater mass that pulled it into an escape?
I'm a layman. Take what I say with skepticism, but I think in this case the parent poster was referring to any mechanism that ends up with a planet getting out of the orbit of the star. One such potential mechanism is gravitational slingshotting.
Let's imagine you have a planet orbiting a star. A satellite flies in towards the planet. As the spacecraft passes by the planet, it gets some of the momentum of the planet as the planet is moving around the star. The planet loses that momentum. This increases the satellite's velocity in relation to the sun. The satellite can reach escape velocity and escape the influence of the star.
Edit: alternatively to reading my explanation, you could read Wikipedia's: https://en.wikipedia.org/wiki/Gravity_assist#Explanation
There's an amazing gif of Voyager 2's slingshots. Pay attention to the velocity as it passes planets: https://en.wikipedia.org/wiki/Gravity_assist#/media/File:Ani...
I don't see why a similar thing couldn't happen to planets.
https://www.google.com/search?q=orbital%20simulator
Play with a few orbital simulators. Many are quite simple, but others allow a great deal of flexibility. It's actually quite a tricky business to get more than a few massive bodies into stable orbits -- gravity alone leads to extremely chaotic systems.
Play with a few orbital simulators. Many are quite simple, but others allow a great deal of flexibility. It's actually quite a tricky business to get more than a few massive bodies into stable orbits -- gravity alone leads to extremely chaotic systems.
Imagine a planet
In the UK there was a recent series on “The Planets” by Brian Cox - one of the things I learnt was how a large has giant had migrated over time from the outer solar system to the inner and back out to the outer. That type of event have caused a slingshot to accelerate a planet like Venus into a highly elliptical orbit, one which might be further accelerated by other planets to a point where it reached escape velocity - especially if combined with large collisions.
This would happen in the same way the voyagers gained speed as it flew past the gas giants in the 80s.
It’s unlikely, but there are a lot of solar systems and a lot of planets.
Predicting the location of a given rogue planet would be like predicting the position if a tractor in a given field in Nebraska. However once you see the tractor is there you can start to predict how it got there.
In the UK there was a recent series on “The Planets” by Brian Cox - one of the things I learnt was how a large has giant had migrated over time from the outer solar system to the inner and back out to the outer. That type of event have caused a slingshot to accelerate a planet like Venus into a highly elliptical orbit, one which might be further accelerated by other planets to a point where it reached escape velocity - especially if combined with large collisions.
This would happen in the same way the voyagers gained speed as it flew past the gas giants in the 80s.
It’s unlikely, but there are a lot of solar systems and a lot of planets.
Predicting the location of a given rogue planet would be like predicting the position if a tractor in a given field in Nebraska. However once you see the tractor is there you can start to predict how it got there.
> After billions of years, I would expect all planets be attached (gravitationally) to a star, shouldn't they?
Planets are formed around stars, but some escape due to gravitational slingshotting etc.. Some of those might be caught again, but why would you think all are?
Planets are formed around stars, but some escape due to gravitational slingshotting etc.. Some of those might be caught again, but why would you think all are?
The down votes are a bit harsh. Theories of planet formation may be familiar to some of us but clearly not everyone, and if you aren’t intimately familiar with orbital mechanics it might not be obvious that rouge planets are expected to be fairly common. We all get to be one of the lucky 10,000 from time to time.
https://xkcd.com/1053/
https://xkcd.com/1053/
On a related note, it's possible to have rogue solar systems as well: https://medium.com/starts-with-a-bang/ask-ethan-can-stars-es...