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Discovered: The Most-Distant Solar System Object Ever Observed

91 points by InInteraction 8y ago

everdev 8y ago
It makes me wonder if there's a distance so great in the observable universe that light from an object would spread out so much that it couldn't be recognized as an object. I'd imagine there are distant stars ejected from galaxies that would render only as single pixel. It seems possible given enough distance that an entire galaxy could render as a single pixel as well, but I wonder if that distance is greater than the observable universe.
- PeanutNore 8y ago
  What exactly do you mean by "render only as a single pixel"? With a low enough resolution sensor, the sun would render as a single pixel when observed from earth.
  - stcredzero 8y ago
    A guy who worked at the undergraduate computer lab when I was in college in the 90's was bemused by all of the print samples and signs by the laser printers, so he made his own: The caption read, "This is Chris rendered in one color at 1 DPI on the Dinotronic," underneath a 7x7 monochrome portrait of himself.
- jstanley 8y ago
  Whether an object falls on to a sensor as a single pixel depends on the magnification (assuming it's correctly focused). Is there a physical limit on how much magnification is possible?
  - kswillister 8y ago
    There's a limit imposed on resolution for earth-based telescopes due to blurring caused by Earth's atmosphere. https://en.wikipedia.org/wiki/Astronomical_seeing#The_full_width_at_half_maximum_(FWHM)_of_the_seeing_disc https://en.wikipedia.org/wiki/Astronomical_seeing#The_full_w...
- kswillister 8y ago
  when you say "a single pixel" here I believe you mean a very small angular diameter
- woodandsteel 8y ago
  For a reflecting telescope, how many pixels are received from a given object depends in part on the surface area of the main mirror.
- xelxebar 8y ago
  There certainly are telescopes that capture images of objects so faint we have to wait long periods of time just to catch a few photons. This is enough to do some interesting astronomy, perhaps surprisingly. If you have a big enough telescope and point it at something long enough, you can almost always resolve it better than just one pixel. There is one hard physical limit though. Due to the expansion of space, there are in fact objects so far away that their light will never reach Earth---one might say that space is expanding them away from us at faster than the speed of light. And because this expansion is actually getting faster all objects are actually accelerating away from us. That means all the time, there are objects that speed up from sub-lightspeed to super-lightspeed as they move away from us. Once they cross that lightspeed barrier, their light can never reach us again. So it's concievable that we might just happen to capture the last photon of some object that will ever reach us. In that sense, then, some objects are indeed so far away that for a brief period of time, any image of them can only hope to be a single pixel, no matter how good your resolution or magnification.
- planteen 8y ago
  I think part of what you are asking is, "If we can't resolve the disk of a object, how do we know if it is a galaxy or a star?" The answer is that we can tell a lot about a point source based on its spectrum. For example, quasars were first noticed solely by their spectra. The other thing to consider with distant galaxies is that they are moving away from us very quickly. The further away they are, the faster they are receding, and the more red-shifted their spectrum becomes. This is why JWST has different spectral response from Hubble.
jstanley 8y ago
Proxima Centauri is about 4.24ly away and has a mass of about 0.12x the mass of the sun. I think that means our sun is the object with the deepest gravity well, out to about (1/1.12)*4.24 = 3.79ly away. I think that means that there could plausibly be objects out to about 3.79ly away that are in orbit around our sun. The object from the article is about 0.0019ly away, so there could be quite a lot of new most-distant solar system objects still to be discovered!
- gammateam 8y ago
  Thats an interesting way to think about things I had always thought of the solar system ending with the planets with some ambiguity about the ort cloud But thinking about it as a system influenced by the biggest gravity well makes a lot more sense
- Thorondor 8y ago
  You're ignoring Alpha Centauri A and B, which are much larger. Also, even without the Alpha Centauri system, very distant orbits (more than 2-3 ly or so) would be destabilized by the galactic tide, i.e. the gravitational gradient of the Milky Way galaxy.
- XaspR8d 8y ago
  Some estimates for the outer boundary of the Oort Cloud put it at 200,000AU = 3.16ly (more conservative estimates seem to be 1ly or less). Even the inner boundary is thought to be at least double the distance of the object just discovered, so current astonomical hypotheses align with your idea that there's a lot more out there.
  - jstanley 8y ago
    Given Thorondor's sibling comment to yours: Alpha Centauri A has a mass of 1.1x the sun, and is about 4.37ly away, which would mean our sun's gravity well runs out at (1/2.1)*4.37 = 2.08ly - i.e. any object in orbit 2.08 ly away would (even if affected by nothing else), fall into Alpha Centauri A's gravity well before completing a full orbit and therefore couldn't possibly remain in orbit around our sun. If that's true (and I have no idea whether any of it is true), then I think 2.08ly must be an upper bound on the outer boundary of the Oort cloud. EDIT: Ah, I'm thinking 2-dimensionally. Of course, something could be in a much larger orbit in a plane that doesn't go near Alpha Centauri.
japaget 8y ago
Technical info from the IAU: https://www.minorplanetcenter.net/mpec/K18/K18Y14.html https://www.minorplanetcenter.net/mpec/K18/K18Y14.html . The orbit is highly uncertain but appears to be highly elliptical, with a perihelion inside the orbit of Neptune and an apogee of roughly 1.5 times the current distance. See also https://www.minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2018+VG18 https://www.minorplanetcenter.net/db_search/show_object?utf8... .
wuliwong 8y ago
I haven't been keeping up on this topic. It's very exciting. If I'm understanding what I've read, this is the furthest of the "dwarf planets" which lie well beyond Pluto. There is a hypothesis that another planet (Planet 9) larger than the earth is out there as well. Planet 9 is what they believe explains some orbital peculiarities shared by these dwarf planets? Is the Planet 9 thought to be even further out than "Farout?"
- KnightOfWords 8y ago
  This object is currently the most distant detected but Sedna's highly eccentric orbit takes it much further from the Sun. Planet Nine's orbit, if it exists, takes it somewhat further away from the Sun than Sedna.
stcredzero 8y ago
People lament the light speed barrier, because it seems to preclude vast space empires of Sci-fi. But there are countless bodies at vast distances just within a few light years. If we develop fusion power, just the neighborhood of the Sun and the Centauri systems would constitute tens of thousands of colonization suitable dwarf planet sized bodies or larger. If we build artificial habitats, the population of all of those systems could easily number in the trillions. That's a pretty vast setting.
- lkrubner 8y ago
  But it is worth asking why people want to believe that a narrative can be extended to space? Humans structure their experience using narratives, and this works okay on Earth. Though even on Earth, there are many known problems with the way humans use narratives: 1.) police will tell you that eye witnesses are highly inaccurate 2.) psychologists can tell you all about the way people hurt themselves with inaccurate narratives about themselves 3.) human rights activists work constantly against narratives that take a racial category as a first class character, with real and knowable attributes And those problems arise on Earth. At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space. And yet people want to this to be true. There is a kind of nostalgia that infects most writing about space, a belief that our exploration of space can be like the discovery of the frontier in centuries past. Even intelligent people sometimes talk this way, even though they know it is an inaccurate way to think about the universe. I suppose this is sort of in the category of "Why do 99% of sci-fi movies act as if there is a gravity on spaceships, or assume a technology that can easily assume that a 1 G warp of the space time continuum does not itself warp the ship into a ball?" Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment. But then we shouldn't take that entertainment and act like any of it can ever be real.
  - stcredzero 8y ago
    At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space. Meh. Human narratives have encompassed characters who live for hundreds of billions of years and who experience time warped in any number of ways. There are even successful mainstream movies that deal with such issues. Multiple ones going back decades. Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment. You could totally re-tell the entire Star Wars and Star Trek canon in such a setting. It's not that people don't want it. Most people don't know enough to know they would want it. Heck, half of everyone seems to think "there's no gravity in space." (EDIT: By "such a setting," I mean in just several cubic light years around Sol and Alpha Centauri.)
lkrubner 8y ago
So this object is a bit more than 11 billion miles from the sun? And Alpha Centauri is 4.2 light years away, which is 24,635,923,200,000 miles? So this object is roughly 0.046% of the way to the next star? Assuming that the Alpha Centauri system reaches out to us as much as our system reaches out to Alpha Centauri, I am surprised that the two systems reach out to each other as much as they do. Almost 10% of the distance between the stars consists of the systems that surround the stars?

91 points by InInteraction 8y ago

It makes me wonder if there's a distance so great in the observable universe that light from an object would spread out so much that it couldn't be recognized as an object. I'd imagine there are distant stars ejected from galaxies that would render only as single pixel. It seems possible given enough distance that an entire galaxy could render as a single pixel as well, but I wonder if that distance is greater than the observable universe.

PeanutNore 8y ago
What exactly do you mean by "render only as a single pixel"? With a low enough resolution sensor, the sun would render as a single pixel when observed from earth.
- stcredzero 8y ago
  A guy who worked at the undergraduate computer lab when I was in college in the 90's was bemused by all of the print samples and signs by the laser printers, so he made his own: The caption read, "This is Chris rendered in one color at 1 DPI on the Dinotronic," underneath a 7x7 monochrome portrait of himself.
jstanley 8y ago
Whether an object falls on to a sensor as a single pixel depends on the magnification (assuming it's correctly focused). Is there a physical limit on how much magnification is possible?
- kswillister 8y ago
  There's a limit imposed on resolution for earth-based telescopes due to blurring caused by Earth's atmosphere. https://en.wikipedia.org/wiki/Astronomical_seeing#The_full_width_at_half_maximum_(FWHM)_of_the_seeing_disc https://en.wikipedia.org/wiki/Astronomical_seeing#The_full_w...
kswillister 8y ago
when you say "a single pixel" here I believe you mean a very small angular diameter
woodandsteel 8y ago
For a reflecting telescope, how many pixels are received from a given object depends in part on the surface area of the main mirror.
xelxebar 8y ago
There certainly are telescopes that capture images of objects so faint we have to wait long periods of time just to catch a few photons. This is enough to do some interesting astronomy, perhaps surprisingly. If you have a big enough telescope and point it at something long enough, you can almost always resolve it better than just one pixel. There is one hard physical limit though. Due to the expansion of space, there are in fact objects so far away that their light will never reach Earth---one might say that space is expanding them away from us at faster than the speed of light. And because this expansion is actually getting faster all objects are actually accelerating away from us. That means all the time, there are objects that speed up from sub-lightspeed to super-lightspeed as they move away from us. Once they cross that lightspeed barrier, their light can never reach us again. So it's concievable that we might just happen to capture the last photon of some object that will ever reach us. In that sense, then, some objects are indeed so far away that for a brief period of time, any image of them can only hope to be a single pixel, no matter how good your resolution or magnification.
planteen 8y ago
I think part of what you are asking is, "If we can't resolve the disk of a object, how do we know if it is a galaxy or a star?" The answer is that we can tell a lot about a point source based on its spectrum. For example, quasars were first noticed solely by their spectra. The other thing to consider with distant galaxies is that they are moving away from us very quickly. The further away they are, the faster they are receding, and the more red-shifted their spectrum becomes. This is why JWST has different spectral response from Hubble.

jstanley 8y ago

Proxima Centauri is about 4.24ly away and has a mass of about 0.12x the mass of the sun. I think that means our sun is the object with the deepest gravity well, out to about (1/1.12)*4.24 = 3.79ly away. I think that means that there could plausibly be objects out to about 3.79ly away that are in orbit around our sun. The object from the article is about 0.0019ly away, so there could be quite a lot of new most-distant solar system objects still to be discovered!

gammateam 8y ago
Thats an interesting way to think about things I had always thought of the solar system ending with the planets with some ambiguity about the ort cloud But thinking about it as a system influenced by the biggest gravity well makes a lot more sense
Thorondor 8y ago
You're ignoring Alpha Centauri A and B, which are much larger. Also, even without the Alpha Centauri system, very distant orbits (more than 2-3 ly or so) would be destabilized by the galactic tide, i.e. the gravitational gradient of the Milky Way galaxy.
XaspR8d 8y ago
Some estimates for the outer boundary of the Oort Cloud put it at 200,000AU = 3.16ly (more conservative estimates seem to be 1ly or less). Even the inner boundary is thought to be at least double the distance of the object just discovered, so current astonomical hypotheses align with your idea that there's a lot more out there.
- jstanley 8y ago
  Given Thorondor's sibling comment to yours: Alpha Centauri A has a mass of 1.1x the sun, and is about 4.37ly away, which would mean our sun's gravity well runs out at (1/2.1)*4.37 = 2.08ly - i.e. any object in orbit 2.08 ly away would (even if affected by nothing else), fall into Alpha Centauri A's gravity well before completing a full orbit and therefore couldn't possibly remain in orbit around our sun. If that's true (and I have no idea whether any of it is true), then I think 2.08ly must be an upper bound on the outer boundary of the Oort cloud. EDIT: Ah, I'm thinking 2-dimensionally. Of course, something could be in a much larger orbit in a plane that doesn't go near Alpha Centauri.

japaget 8y ago

Technical info from the IAU: https://www.minorplanetcenter.net/mpec/K18/K18Y14.html https://www.minorplanetcenter.net/mpec/K18/K18Y14.html . The orbit is highly uncertain but appears to be highly elliptical, with a perihelion inside the orbit of Neptune and an apogee of roughly 1.5 times the current distance. See also https://www.minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2018+VG18 https://www.minorplanetcenter.net/db_search/show_object?utf8... .

wuliwong 8y ago

I haven't been keeping up on this topic. It's very exciting. If I'm understanding what I've read, this is the furthest of the "dwarf planets" which lie well beyond Pluto. There is a hypothesis that another planet (Planet 9) larger than the earth is out there as well. Planet 9 is what they believe explains some orbital peculiarities shared by these dwarf planets? Is the Planet 9 thought to be even further out than "Farout?"

KnightOfWords 8y ago
This object is currently the most distant detected but Sedna's highly eccentric orbit takes it much further from the Sun. Planet Nine's orbit, if it exists, takes it somewhat further away from the Sun than Sedna.

stcredzero 8y ago

People lament the light speed barrier, because it seems to preclude vast space empires of Sci-fi. But there are countless bodies at vast distances just within a few light years. If we develop fusion power, just the neighborhood of the Sun and the Centauri systems would constitute tens of thousands of colonization suitable dwarf planet sized bodies or larger. If we build artificial habitats, the population of all of those systems could easily number in the trillions. That's a pretty vast setting.

lkrubner 8y ago
But it is worth asking why people want to believe that a narrative can be extended to space? Humans structure their experience using narratives, and this works okay on Earth. Though even on Earth, there are many known problems with the way humans use narratives: 1.) police will tell you that eye witnesses are highly inaccurate 2.) psychologists can tell you all about the way people hurt themselves with inaccurate narratives about themselves 3.) human rights activists work constantly against narratives that take a racial category as a first class character, with real and knowable attributes And those problems arise on Earth. At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space. And yet people want to this to be true. There is a kind of nostalgia that infects most writing about space, a belief that our exploration of space can be like the discovery of the frontier in centuries past. Even intelligent people sometimes talk this way, even though they know it is an inaccurate way to think about the universe. I suppose this is sort of in the category of "Why do 99% of sci-fi movies act as if there is a gravity on spaceships, or assume a technology that can easily assume that a 1 G warp of the space time continuum does not itself warp the ship into a ball?" Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment. But then we shouldn't take that entertainment and act like any of it can ever be real.
- stcredzero 8y ago
  At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space. Meh. Human narratives have encompassed characters who live for hundreds of billions of years and who experience time warped in any number of ways. There are even successful mainstream movies that deal with such issues. Multiple ones going back decades. Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment. You could totally re-tell the entire Star Wars and Star Trek canon in such a setting. It's not that people don't want it. Most people don't know enough to know they would want it. Heck, half of everyone seems to think "there's no gravity in space." (EDIT: By "such a setting," I mean in just several cubic light years around Sol and Alpha Centauri.)

lkrubner 8y ago

So this object is a bit more than 11 billion miles from the sun? And Alpha Centauri is 4.2 light years away, which is 24,635,923,200,000 miles? So this object is roughly 0.046% of the way to the next star? Assuming that the Alpha Centauri system reaches out to us as much as our system reaches out to Alpha Centauri, I am surprised that the two systems reach out to each other as much as they do. Almost 10% of the distance between the stars consists of the systems that surround the stars?