Passing stars changed the orbits of planets in the solar system(universetoday.com)
universetoday.com
Passing stars changed the orbits of planets in the solar system
https://www.universetoday.com/165727/passing-stars-changed-the-orbits-of-planets-in-the-solar-system/
74 comments
Given how close the star HD 7977 was 2.8 million years ago, many times closer than any star today, it is pretty much certain that its passage has perturbed the orbits of the planets.
What is uncertain is only which were the changes, i.e. which were the orbits of the planets prior to the star passing.
The changes must have been very small, but they must have existed.
The point of the paper is that this stellar passing and others like it increase by a non-negligible amount the uncertainty of the simulations that attempt to determine accurately the planetary movements in the distant past of the Solar System, at scales of tens of millions of years.
The star HD 7977 is slightly bigger and brighter than the Sun, so when it has passed at the minimum distance there are chances that it was noticeably brighter than Venus.
What is uncertain is only which were the changes, i.e. which were the orbits of the planets prior to the star passing.
The changes must have been very small, but they must have existed.
The point of the paper is that this stellar passing and others like it increase by a non-negligible amount the uncertainty of the simulations that attempt to determine accurately the planetary movements in the distant past of the Solar System, at scales of tens of millions of years.
The star HD 7977 is slightly bigger and brighter than the Sun, so when it has passed at the minimum distance there are chances that it was noticeably brighter than Venus.
In the same vein, Gliese 710 will pass even closer at 0.16 ly from the Sun in 1.29 million years which add uncertainty to the simulation of the distant future.
The other rule of journalism is the author of of a piece doesn't write the headline.
One day sub-editors will be named and shamed for the headlines they excrete onto the world
And will be replaced by chatgpt written headlines that are focused on attracting attention even more flagrantly than today. Today even in 'real newspapers' online you see headlines like "The way to tell if your financial advisor is good is..."
...or in this case, "state theories as if they were facts if it makes a good headline"?
Well, in the "technically correct" department, the stars all do, even if it's on the order of attometers or whatever. It's set up to pass the fact-checking, so yeah, that's just about the standards of modern journalism.
I'm sick and tired of the more or less concerted attack on journalists with every opportunity. Bad media have been around as long as there have been media, if you think the standards of modern journalism have dropped you are either looking at things through a very local lens or simply not well informed about mass media through the ages. But quality content exists if you're willing to pay for it, which is how it has always been. Free content, whether in print or on the web can be very good but as a rule if it is brought to you by a commercial entity you have to always question the value of the words and their relation to commercial interests.
Whilst I agree with you, there has always been bad journalism, I have been reading the same newspaper for many years and have had a paid subscription to it.
The problem is, as the paid readers fall, they are forced to use clickbait titles to attract more on line readers to click ads. Imagine a newspaper founded in 1831, using titles like, "You will never guess what she said next" as a main headline.
The same here, who is going to click on "Passing stars may affect the orbits of our planets"? They know exactly what they are doing and it's not about the scientifically literate.
The problem is, as the paid readers fall, they are forced to use clickbait titles to attract more on line readers to click ads. Imagine a newspaper founded in 1831, using titles like, "You will never guess what she said next" as a main headline.
The same here, who is going to click on "Passing stars may affect the orbits of our planets"? They know exactly what they are doing and it's not about the scientifically literate.
The media landscape has always been shifting and business models change over time. The internet pretty much put paid newspapers out of business, circulation is a fraction of what it used to be. TV started it, the internet ended it. So just like with everything else it changes, just like you don't normally complain about how 'art galleries show crap today' because your favorite art galleries have gone down the tubes you move to new ones or you directly patronize the artists that you like. A similar thing happens to journalism.
I get where you are coming from, but journalists today aren't real journalists. Public trust in media is at an all-time low for a reason.
I understand that real journalism must be paid for, but allowing megacorps to buy up all maintream media was a huge mistake and now they are all corporate mouthpieces.
I don't know what the answer is, but trusting 'journalists' of today is not it.
The head of journalism at my college warned us of this over a decade ago, and he didn't have the answer either. They lost their ethics in search of clicks and clout and cry foul when they aren't believed. They use divisive language, outright lie, holy crap this election cycle will be a shitshow. There's no unbiased truth finders anymore.
The ones I feel sorry for are the real journalists drowned out by the fake.
I understand that real journalism must be paid for, but allowing megacorps to buy up all maintream media was a huge mistake and now they are all corporate mouthpieces.
I don't know what the answer is, but trusting 'journalists' of today is not it.
The head of journalism at my college warned us of this over a decade ago, and he didn't have the answer either. They lost their ethics in search of clicks and clout and cry foul when they aren't believed. They use divisive language, outright lie, holy crap this election cycle will be a shitshow. There's no unbiased truth finders anymore.
The ones I feel sorry for are the real journalists drowned out by the fake.
> I get where you are coming from, but journalists today aren't real journalists.
Some are, some aren't. Just like some programmers are real programmers and others are not, and some managers are real managers and others are not. The world is full of posers but that doesn't mean there aren't people that hold the title + the ethics that come with it dear. They're a minority, but they've always been a minority, that didn't change at all.
> Public trust in media is at an all-time low for a reason.
It mostly is because there are well funded political groups that incessantly undermine the public trust in the media. Because the last thing they want is for their deeds to be properly exposed and investigated.
> I understand that real journalism must be paid for, but allowing megacorps to buy up all maintream media was a huge mistake and now they are all corporate mouthpieces.
> I don't know what the answer is, but trusting 'journalists' of today is not it.
Well, one thing that could be done is to seriously limit ownership of media by global empires. The likes of Murdoch have done untold damage to the world in the pursuit of some green paper.
> The head of journalism at my college warned us of this over a decade ago, and he didn't have the answer either.
Yes, it is a problem. And given the cost of good investigative journalism it is in fact unbelievable that there are still people doing this because they see it as their calling. And I'm mighty impressed with that and do not accept the broad brush with which they too are being painted. In every country you can find journalists that operate with integrity and that are not to be muzzled by corporate interests. They're real heroes too because in plenty of places that will get you ostracized, beaten up, blacklisted or murdered.
> They lost their ethics in search of clicks and clout and cry foul when they aren't believed.
Some. Not all.
> They use divisive language, outright lie, holy crap this election cycle will be a shitshow. There's no unbiased truth finders anymore.
There are, just not all that many, but they do exist.
> The ones I feel sorry for are the real journalists drowned out by the fake.
So, it seems we agree they exist. My solution is pretty simple, I seek out the journalists whose work I trust and I try to get my information about country A from any source except the ones in country A because they likely will not be objective. That's a hack and a workaround but it seems to work quite well.
Some are, some aren't. Just like some programmers are real programmers and others are not, and some managers are real managers and others are not. The world is full of posers but that doesn't mean there aren't people that hold the title + the ethics that come with it dear. They're a minority, but they've always been a minority, that didn't change at all.
> Public trust in media is at an all-time low for a reason.
It mostly is because there are well funded political groups that incessantly undermine the public trust in the media. Because the last thing they want is for their deeds to be properly exposed and investigated.
> I understand that real journalism must be paid for, but allowing megacorps to buy up all maintream media was a huge mistake and now they are all corporate mouthpieces.
> I don't know what the answer is, but trusting 'journalists' of today is not it.
Well, one thing that could be done is to seriously limit ownership of media by global empires. The likes of Murdoch have done untold damage to the world in the pursuit of some green paper.
> The head of journalism at my college warned us of this over a decade ago, and he didn't have the answer either.
Yes, it is a problem. And given the cost of good investigative journalism it is in fact unbelievable that there are still people doing this because they see it as their calling. And I'm mighty impressed with that and do not accept the broad brush with which they too are being painted. In every country you can find journalists that operate with integrity and that are not to be muzzled by corporate interests. They're real heroes too because in plenty of places that will get you ostracized, beaten up, blacklisted or murdered.
> They lost their ethics in search of clicks and clout and cry foul when they aren't believed.
Some. Not all.
> They use divisive language, outright lie, holy crap this election cycle will be a shitshow. There's no unbiased truth finders anymore.
There are, just not all that many, but they do exist.
> The ones I feel sorry for are the real journalists drowned out by the fake.
So, it seems we agree they exist. My solution is pretty simple, I seek out the journalists whose work I trust and I try to get my information about country A from any source except the ones in country A because they likely will not be objective. That's a hack and a workaround but it seems to work quite well.
Lots of things that have existed for long are no longer tolerated. Racism and sexism for two prominent examples. Expecting high standards from those tasked with informing the public seems very reasonable to me.
There always has been a dividing line between quality journalism and what amounts to clickbait. Bild was a thing when I grew up. If you want better journalism pay for it. The whole idea that news and media should be free is part and parcel of the destruction of quality journalism and it is the very same people bitching about the quality of journalism that want all of their news to be free. No matter how poor we were my mom was paying for a newspaper because she felt it important to stay informed and for us to stay informed. That newspaper may have slowly died on account of the TV and the Internet but those journalists still exist and if you put some effort into it you can find them.
You are correct - I have no problem paying a reasonable fee for good journalism to be informed.
The problem is that poor journalism influences the masses. And in a democracy, the masses' opinion is assigned a higher decision-making weight than is the opinion of the informed minority.
The problem is that poor journalism influences the masses. And in a democracy, the masses' opinion is assigned a higher decision-making weight than is the opinion of the informed minority.
Yes, that is a massive problem. But I don't blame the journalists per se: the masses are part and parcel of that and they collectively seem to prefer to be lied to over the unvarnished truth, which as often as not is very uncomfortable. People want simplicity and predictability, they don't want to have to exercise their grey matter too much, they don't want to be inconvenienced and they - and this one really gets me - would prefer not to know. That makes it easier to ignore things and to focus on the little joys in life instead of on the overarching much larger troubles.
That sounds like quite the argument against democracy.
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Great short article. Takeaway: because of ancient star flybys
"the uncertainties of Earth’s past orbit make it difficult to be confident more than 50 million years. And that has a significant impact on paleoclimate studies."
"the uncertainties of Earth’s past orbit make it difficult to be confident more than 50 million years. And that has a significant impact on paleoclimate studies."
That's actually fascinating! Among other things passing stars can do, I imagine, is knock comets out of the Ort cloud? So speaking of dinosaurs...
Lisa Randall's book "Dark Matter and the Dinosaurs" has that vibe (not about passing stars, but about the solar system passing through an area of the galaxy thick with dark matter - but the imagined impact is the same).
Maybe dinosaurs jumped to another star that time and arranged some fireworks to ensure no one will follow?
The butterfly effect, where the 'butterfly' is a stellar object.
In university I coded an N-body simulator and visualizer. This was back before when we had so many games that exist now. It taught me a lot about orbital mechanics.
One realization I had was how orbits were fragile and how easily you could shift them with influence from very far away.
Another realization- gravity is weak, but it decreases over a huge distance compared to other forces we normally experience in human scale.
One realization I had was how orbits were fragile and how easily you could shift them with influence from very far away.
Another realization- gravity is weak, but it decreases over a huge distance compared to other forces we normally experience in human scale.
Does gravity decrease more slowly than other forces, or is it so weak that the gravity sources we feel are enormous and therefore have long radii of non-negligible effect, or is it something else?
Gravity and electromagnetism both obey inverse square laws, but electromagnetism is negligible on astronomical scales because positive and negative charges cancel so astronomical objects are electrically neutral (or close enough to it that electromagnetic effects are negligible).
The strong and weak interactions are only significant on very short distance scales; from the standpoint of "force laws" you can think of them as having an exponential decay with distance that makes them drop off to essentially nothing by the time you get to distances much larger than the size of an atomic nucleus. (That's an oversimplification, but it's enough to see why you can ignore them on astronomical scales.)
The strong and weak interactions are only significant on very short distance scales; from the standpoint of "force laws" you can think of them as having an exponential decay with distance that makes them drop off to essentially nothing by the time you get to distances much larger than the size of an atomic nucleus. (That's an oversimplification, but it's enough to see why you can ignore them on astronomical scales.)
The electric force cancels over short distances. Magnetic force may act over multi-light-year distances, as may be easily seen in the turbulent flow of luminous plasma visible near supernova remnants, supermassive black holes, and in star-forming regions. Turbulent flow of neutral gases at such pressure and scale is impossible because collisions are too infrequent.
> Magnetic force may act over multi-light-year distances, as may be easily seen in the turbulent flow of luminous plasma
The plasma itself is magnetic, so the magnetic force itself is not acting over multi-light-year distances; the material carrying the magnetism is traveling over those distances and bringing its magnetism with it.
Also, this magnetism doesn't affect the orbits of planets or stars; my original statement was focused on what affects those things.
The plasma itself is magnetic, so the magnetic force itself is not acting over multi-light-year distances; the material carrying the magnetism is traveling over those distances and bringing its magnetism with it.
Also, this magnetism doesn't affect the orbits of planets or stars; my original statement was focused on what affects those things.
And, that material's magnetism is interacting with magnetism carried by other material. Turbulently. And affecting the motion of all the material.
I agree with GP, the measurable effects of the magnetic field are not strong, it's just that they're close because charged particles carried them close.
Maybe a better electromagnetic example would be radio signals from pulsars, which are enormous and travel great distances and still provide measurable signals even if they are light years away. We cannot on earth measure the gravity of these objects, nor the atomic forces, but we can readily meausure their electromagnetic sprayings.
Maybe a better electromagnetic example would be radio signals from pulsars, which are enormous and travel great distances and still provide measurable signals even if they are light years away. We cannot on earth measure the gravity of these objects, nor the atomic forces, but we can readily meausure their electromagnetic sprayings.
Yet, nearly all of the extended structure of luminous interstellar gas we see in the best pics on APOD is the plasma fluid interaction that astrronomers can't be bothered about. SOFIA could have revealed much, if not grounded. Are any of the new orbital telescopes about to come online equipped to record polarization?
Is there somewhere that assesses the EM impact of things?
As I understand it, planetary magnetic fields influence solar winds; stellar ones structures in the galaxy; etc.
I’d really like to learn more (preferably, with numbers).
As I understand it, planetary magnetic fields influence solar winds; stellar ones structures in the galaxy; etc.
I’d really like to learn more (preferably, with numbers).
Astronomers, as a rule, detest all discussion of EM, often going so far as to label people who insist on discussing it cranks. There are exceptions, but also cranks. It can be hard for the public to tell them apart. Astronomers do not assist, perhaps for fear of being labeled cranks themselves.
This has been a large frustration of mine:
I know from talks that filaments[0], galactic lobes[1], structure of arms[2], etc relate to EM — but finding anything at the layperson level is basically impossible. Just short blog posts, but no real explanation of how this all relates or what drives it.
Harumph, I say!
[0] - https://www.livescience.com/radio-filaments-milky-way-center
[1] - https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=10918
[2] - https://blogs.nasa.gov/sofia/2022/04/05/make-no-bones-about-...
I know from talks that filaments[0], galactic lobes[1], structure of arms[2], etc relate to EM — but finding anything at the layperson level is basically impossible. Just short blog posts, but no real explanation of how this all relates or what drives it.
Harumph, I say!
[0] - https://www.livescience.com/radio-filaments-milky-way-center
[1] - https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=10918
[2] - https://blogs.nasa.gov/sofia/2022/04/05/make-no-bones-about-...
The fact of E-M fields affecting the motion of mass, in preference to or in addition to gravitation, is anathema.
To hint at any role of E-M in the large-scale evolution of the universe is a good way to eliminate any possibility of a research grant. Probably this is just because the people deciding don't want to be obliged to learn how to evaluate whether the research program makes any sense. So, plasma fluid dynamics work normally is studied only at the scale of an individual planet or star, or at most a galaxy.
SOFIA, the telescope carried in a Boeing 747, lost its funding in part because mainstream astronomers found its unique capability of mapping magnetic polarization uninteresting.
To hint at any role of E-M in the large-scale evolution of the universe is a good way to eliminate any possibility of a research grant. Probably this is just because the people deciding don't want to be obliged to learn how to evaluate whether the research program makes any sense. So, plasma fluid dynamics work normally is studied only at the scale of an individual planet or star, or at most a galaxy.
SOFIA, the telescope carried in a Boeing 747, lost its funding in part because mainstream astronomers found its unique capability of mapping magnetic polarization uninteresting.
> As I understand it, planetary magnetic fields influence solar winds; stellar ones structures in the galaxy; etc.
Yes, I was oversimplifying somewhat. Magnetic fields don't affect things like the orbits of planets or stars. But they do have other effects on astronomical scales.
Yes, I was oversimplifying somewhat. Magnetic fields don't affect things like the orbits of planets or stars. But they do have other effects on astronomical scales.
Gravity doesn't cancel like the electromagnetic force, despite otherwise decreasing at the same rate.
I've never heard an explanation of the strong or weak forces that I actually "get" enough to understand their distance effects.
I've never heard an explanation of the strong or weak forces that I actually "get" enough to understand their distance effects.
>I've never heard an explanation of the strong
> or weak forces that I actually "get"
I thought this was excellent (in all ways) but particularly for your question: https://www.youtube.com/watch?v=UYW1lKNVI90
I thought this was excellent (in all ways) but particularly for your question: https://www.youtube.com/watch?v=UYW1lKNVI90
In case anyone else wants to watch: the weak force isn't mentioned until just after the 45-minute mark. I haven't got to the strong force yet but it presumably follows.
Edit: so for weak, I think I understand that "photons are massless, so are only subject to the inverse-square law; weak bosons have mass, so are also subject to decay". But that doesn't explain to this dummy how the strong force works, since gluons are also massless (... though mesons are not? but they're not fundamental).
Edit: so for weak, I think I understand that "photons are massless, so are only subject to the inverse-square law; weak bosons have mass, so are also subject to decay". But that doesn't explain to this dummy how the strong force works, since gluons are also massless (... though mesons are not? but they're not fundamental).
I often think about how stars come within 1 light year of our Sun every 300,000 years. It's pretty wild. And then I have to worry about rogue planets, meteorites, and obfuscated stars going supernova. What are the odds we're here?
This also means very long lived extraterrestrial civilizations can colonize the galaxy with slow very short range starships. Just wait for stars to come within a fraction of a light year and send over ships at 1% of the speed of light (or even slower). The star will move away, and it also becomes a target for close approaches of stars. The number of colonized stars grows exponentially (if gradually) until most stars have been colonized.
> very long lived extraterrestrial civilizations
We're talking about stellar visitors that arrive every 20 million years or so. We have no evidence of any civilization that lasted much more than 1,000 years.
So you're going to hitch a ride with a stellar visitor, with a view to colonizing the galaxy? Suppose the visitor comes as close as a few thousand AU, and the colonist ship can reach it in a hundred years or so; cool. But how long before the visitor reaches the next star on its tour? That's going to be millions of years.
So the colonists set up camp on a planet orbiting the visitor; the hypothesis is "a very long-lived" civilization, so we assume they have brought their knowledge with them to this camp, from the home planet, and are able to conserve it (strong assumption). But for tens of millions of years?
Civilizations evolve much more quickly than organisms, if Earth history is anything to go by. It seems far-fetched that a civilization might survive the evolution of the underlying organism; there's something Canute-like about trying to preserve a civilization in the teeth of genetic evolution. Evolution is going to happen, even during the initial journey to the visitor.
I'm very sceptical about this notion of "very long lived extraterrestrial civilizations".
We're talking about stellar visitors that arrive every 20 million years or so. We have no evidence of any civilization that lasted much more than 1,000 years.
So you're going to hitch a ride with a stellar visitor, with a view to colonizing the galaxy? Suppose the visitor comes as close as a few thousand AU, and the colonist ship can reach it in a hundred years or so; cool. But how long before the visitor reaches the next star on its tour? That's going to be millions of years.
So the colonists set up camp on a planet orbiting the visitor; the hypothesis is "a very long-lived" civilization, so we assume they have brought their knowledge with them to this camp, from the home planet, and are able to conserve it (strong assumption). But for tens of millions of years?
Civilizations evolve much more quickly than organisms, if Earth history is anything to go by. It seems far-fetched that a civilization might survive the evolution of the underlying organism; there's something Canute-like about trying to preserve a civilization in the teeth of genetic evolution. Evolution is going to happen, even during the initial journey to the visitor.
I'm very sceptical about this notion of "very long lived extraterrestrial civilizations".
The civilizations themselves don't have to be long lived, but once a star system is colonized it has to stay inhabited long enough. Civilizations could come and go, but not completely die out too quickly. As long as each colonized star system produces enough child colonies before it dies out the exponential growth will continue, with colonies eventually being reestablished at systems where former colonies may have expired.
Eventually there would be selection for colonies that can produce faster and/or longer lived colony ships, so they can plant new colonies faster. This will eventually shade over into the more conventional galactic colonization scenarios where stars can be treated as near stationary.
Eventually there would be selection for colonies that can produce faster and/or longer lived colony ships, so they can plant new colonies faster. This will eventually shade over into the more conventional galactic colonization scenarios where stars can be treated as near stationary.
Technically, you can stop evolution from happening. Cloning is annoying, but if you had enough compute and algorithms you should be able to make in-place edits to stop drift. By "in-place" I mean even optimistically just a bit after the blastocyst phase, editing humans that are even slightly grown to that level is just not going to be practical.
> Technically, you can stop evolution from happening.
Yeah, but would anyone do that to an entire civilization? Evolution leads to greater 'fitness' - improved adaptation to the environment. The travellers are jumping from $HOME_PLANET, into a generation ship, onto a new planet presenting novel adaptation challenges. That planet's star-system then eventually sets off on a long journey, until it encounters a new star. Each of these stages takes many times the time humans have existed on Earth. If you consider only modern humans, we've only been around for 50,000 years, maybe.
And "modern humans" isn't a civilization; it's really all of the different, successive human civilizations.
If you could imagine that, in addition to making stone tools and animal-hide clothes, neanderthals had also learned how to freeze evolution, do you think those guys would be well-adapted to a planet-hopping future? I don't.
Yeah, but would anyone do that to an entire civilization? Evolution leads to greater 'fitness' - improved adaptation to the environment. The travellers are jumping from $HOME_PLANET, into a generation ship, onto a new planet presenting novel adaptation challenges. That planet's star-system then eventually sets off on a long journey, until it encounters a new star. Each of these stages takes many times the time humans have existed on Earth. If you consider only modern humans, we've only been around for 50,000 years, maybe.
And "modern humans" isn't a civilization; it's really all of the different, successive human civilizations.
If you could imagine that, in addition to making stone tools and animal-hide clothes, neanderthals had also learned how to freeze evolution, do you think those guys would be well-adapted to a planet-hopping future? I don't.
Once you have the technology to freeze evolution, you also have the technology to accelerate it and steer it, and given the level of incentive (to gain competitive advantage), I don't imagine it would be a balanced sword-and-shield race in the long run. The "conservatives" couldn't keep up with the "modernists", unless it's some sort of a totalitarian system.
There's been this great (relatively) short story, both humorous and profound, by Stanisław Lem; "The Twenty-first Voyage" in "The Star Diaries". It's based on that exact premise.
There's been this great (relatively) short story, both humorous and profound, by Stanisław Lem; "The Twenty-first Voyage" in "The Star Diaries". It's based on that exact premise.
At a rough guess, even with an approach between stars that's very close, the difference in velocities between them may make for swapping between the two systems near impossible.
There could be a good measure of good luck needed too. eg the spaceship is lucky enough to get some gravitational assistance from a large body or two in the target system
There could be a good measure of good luck needed too. eg the spaceship is lucky enough to get some gravitational assistance from a large body or two in the target system
The average relative velocity of stars in the Sun's neighborhood is about 30 km/s. For certain high velocity stars, it can be in the hundreds of km/s (but those are particularly interesting as they leave to enable colonization of new parts of the galaxy much more quickly.)
If the time between encounters is a million years, at 30 km/s the stars will have separated by 100 light years.
If the time between encounters is a million years, at 30 km/s the stars will have separated by 100 light years.
> 30 km/s
Given the likely time scales, do you reckon that'd be challenging?
To me, that sounds like an awful lot of acceleration would be needed.
Given the likely time scales, do you reckon that'd be challenging?
To me, that sounds like an awful lot of acceleration would be needed.
Getting from earth's surface to low earth orbit is about equivalent to accelerating by 9 km/s, in terms of fuel. Some it lost to drag and gravity, but at the orbit of the ISS you have an orbital sites of about 7.6 km/s.
If you could teleport a fully fueled Saturn V into orbit, it could speed up by about 18 km/s. More if you reduced the payload.
Of course going from 18 to 30 exposes you to the tyranny of the rocket equation: to go faster you need more fuel, which makes your rocket heavier, which means it needs more fuel, which makes your rocket heavier, ... Any small efficiency increase matters a lot here. It might be possible with today's tech if you build the rocket in orbit (which gets rid of aerodynamic constrains), or alternatively with orbital refueling and a couple more decades of progress in more efficient engine types (which you could greatly accelerate by throwing money at it).
If you could teleport a fully fueled Saturn V into orbit, it could speed up by about 18 km/s. More if you reduced the payload.
Of course going from 18 to 30 exposes you to the tyranny of the rocket equation: to go faster you need more fuel, which makes your rocket heavier, which means it needs more fuel, which makes your rocket heavier, ... Any small efficiency increase matters a lot here. It might be possible with today's tech if you build the rocket in orbit (which gets rid of aerodynamic constrains), or alternatively with orbital refueling and a couple more decades of progress in more efficient engine types (which you could greatly accelerate by throwing money at it).
Just using chemical rockets, speeds at infinity in excess of 100 km/s are possible using the Oberth effect: go into an elliptical orbit that passes close to the Sun, then accelerate at perihelion. Because the change in kinetic energy is thrust times velocity, and velocity is very high, large amounts of energy are added to the vehicle. The source of this energy is that the ejected propellant is left at low gravitational potential relative to where it was initially.
Solar sails released at perihelion can also achieve very high speeds.
Slowing down in the target system could be done with solar sails or electrodynamic sails (working on the stellar wind).
Ion or plasma engines are another possibility, with nuclear power plants.
Solar sails released at perihelion can also achieve very high speeds.
Slowing down in the target system could be done with solar sails or electrodynamic sails (working on the stellar wind).
Ion or plasma engines are another possibility, with nuclear power plants.
There is also the issue of losing speed as you climb up out of the Sun's gravity well. You gain some of it back by falling into the close approach star's gravity well, but from what I can tell, the close approach star is likely to be considerably less massive than the Sun, so you won't gain back all of what you lost. Which means you need even more rocket power.
Changing speed by 30 km/s would "only" require 51 minutes of acceleration at 1 g (9.8 m/s/s):
https://www.wolframalpha.com/input?i=%2830+km%2Fs%29%2Fg&ass...
https://www.wolframalpha.com/input?i=%2830+km%2Fs%29%2Fg&ass...
Interesting, thanks. :)
The required accelerations would be quite small, given the time the trip would take.
Okay that’s a lot slower than I’d have imagined. Won’t be getting as much out of a flyby / gravitational slingshot as I’d have hoped.
Sorry, I'm not getting this. The star will move away from what? Wouldn't the spaceship move with the star? I apologize if I'm misinterpreting what you said
Once you've colonised the star system during its close passage to your own, it will continue its journey and eventually pass nearby other star systems, which can then be colonised as well. So every colony will spawn more colonies, leading to exponential growth.
At least I think that's what they meant. It's an interesting idea for sure.
At least I think that's what they meant. It's an interesting idea for sure.
Yes, that's exactly what I meant.
I think they mean that if you start in solar system A, when solar system B flies by, you enter its gravity and colonize the system. Eventually solar system B will fly by solar system C, where you can repeat the process.
B-Arc
Gliese 710 will be at a 0.16ly distance in 1.3 million years. Well within the Oort Cloud.
https://en.wikipedia.org/wiki/Gliese_710
https://en.wikipedia.org/wiki/Gliese_710
Quick! Someone write a sci-fi screenplay set in that time period!
A star inside the Oort Cloud might start another inner system bombardment.
A star inside the Oort Cloud might start another inner system bombardment.
> Right now the star is about 250 light-years away, but 2.8 million years ago it passed within 30,000 AU or half a light-year of the Sun. It may have passed as close as 4,000 AU from the Sun.
This blew my mind. I never considered that stars are moving relatively each other in this way. Or more precisely, what it meant for our solar system.
This blew my mind. I never considered that stars are moving relatively each other in this way. Or more precisely, what it meant for our solar system.
Sometimes people talk about hypothetical generation ships and the ethics of bringing children into such a situation where they will be expected to continue the mission throughout their lives. What’s funny is that in some sense we’re already on quite a large starship wondering near aimlessly through the galaxy. Obviously we could be treating it with much greater care than we currently are.
If we never figure out FTL, if relativistic travel is hamstrung by blue shifting of particles and radiation in front of the craft, then the only other way we wander the galaxy is to hop over to a passing star.
The question is, can you make a ship fast enough to catch a star going past, or do you have to launch ahead of time. And do you have enough time in either case to decide if this one way trip is suicide or not.
Practically the window of opportunity for a favorable launch may not might not be that different than launching for Proxima Centauri. But at least you can soak up solar power and mine resources while you wait, instead of sitting in the dark the entire time.
The question is, can you make a ship fast enough to catch a star going past, or do you have to launch ahead of time. And do you have enough time in either case to decide if this one way trip is suicide or not.
Practically the window of opportunity for a favorable launch may not might not be that different than launching for Proxima Centauri. But at least you can soak up solar power and mine resources while you wait, instead of sitting in the dark the entire time.
> how stars come within 1 light year of our Sun every 300,000 years.
A few years ago, research using Gaia data indicated that the last such close encounter was about 70,000 years ago, when the star WISE J072003.20-084651.2 — also called Scholz’s Star, after the discoverer — passed just 0.8 light-years from the Sun.
- https://www.syfy.com/syfy-wire/bad-astronomy-several-stars-h...
A few years ago, research using Gaia data indicated that the last such close encounter was about 70,000 years ago, when the star WISE J072003.20-084651.2 — also called Scholz’s Star, after the discoverer — passed just 0.8 light-years from the Sun.
- https://www.syfy.com/syfy-wire/bad-astronomy-several-stars-h...
The picture is misleading. Scholz's star is a dwarf and was not visible by the naked eye even at closest approach, unless it happened to flare at the time (and even then would have been like the thousandth brightest object in the sky).
https://www.pas.rochester.edu/~emamajek/flyby.html
https://www.pas.rochester.edu/~emamajek/flyby.html
If you're interested in this topic, you might also be interested in the idea that there is a Brown Dwarf hidden near our solar system that causes periodic extinctions on Earth, because it periodically messes up the comet shield provided by the Sun and gas giants.
[1] https://en.m.wikipedia.org/wiki/Nemesis_(hypothetical_star)
[1] https://en.m.wikipedia.org/wiki/Nemesis_(hypothetical_star)
As an interesting related tangent, one of the largest asteroids in the solar system, Juno (~250km diameter), changed its orbit in the 19th century and there is no evidence what caused it.
Talks about an event several dozens of million years ago. Shows a picture of a hominid looking at a star. Keep up the good work!
I wish they'd put that "little detail" prominently in the title. Without it, this becomes fodder for people who believe in astrology. Maybe this was the idea...
The paper, linked, https://iopscience.iop.org/article/10.3847/2041-8213/ad24fb, does go into the chaotic behavior and why it's all kinda sorta made up.