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The question that the general public always wants answered is roughly, "If I was floating in a safe glass bubble in outer space looking at this object with my e

The question that the general public always wants answered is roughly, "If I was floating in a safe glass bubble in outer space looking at this object with my eyes, what would I see?" Does anyone know the answer to this? Would it just be black? Or just a bright white star?

cconstantine 1y ago
For the vast majority of things in the sky, they'd see black. This stuff is incredibly dark, and we need hours of exposure time to get enough signal. Even after hours of exposure the raw stacked frame is a black field with some pinpoints of lights. The exception to this is stuff in our own solar system.
hnuser123456 1y ago
Well, some of the densest, nearest, most interesting structures are right behind the rest of the Milky Way, which causes up to 30 magnitudes of extinction in visible light, but deeper IR and UV passes through much more easily. I think a better way to describe the issue is that much of the structure of the cosmos is only visible in non-visible wavelengths, so while calibrated, accurate visuals "like you were in a safe glass bubble" is a good category of astrophotography to continue to refine, it's a tiny slice of what's emitting electromagnetic radiation that's worth visualizing. And if cameras can convert invisible colors into visible ones, that's a blessing of a capability.
- yig 1y ago
  Can we infer what that visible light would look like unobstructed and with appropriate intensity to activate our eyes' cones?
  - hnuser123456 1y ago
    Not necessarily, various objects can look completely different in different wavelengths and it's not really possible to interpolate without taking a picture of each part of the spectrum.
- jacobr1 1y ago
  Even in the case of the Milky Way blocking the light, we could probably do the math to estimate would an observer would see if they were outside the Milky Way, interpolating from the observed IR/UV and some model of the visible spectra would be be without the local interference. Or is that infeasible in some way? Certainly some phenomena just don't have much visible light of interest - so shifting the the spectra is inherently necessary in those cases and is thus inherently subjective.
  - hnuser123456 1y ago
    Not necessarily, various objects can look completely different in different wavelengths and it's not really possible to interpolate without taking a picture of each part of the spectrum. The Milky Way and the entire local group of galaxies are flowing towards the superclusters located directly on the opposite side of the galaxy, and there's huge (thousands of light years) clouds of gas and "dust" (supernova molecular feces) that are like actual, thick, opaque storm clouds that form a donut around the galaxy, so it's impossible to "see" where we're headed except for the the X-rays and mid-infrared that doesn't interact with the huge clouds. And we won't be able to until we can leave the plane of the Milky Way's disk, or we build a telescope that is 2 dozen orders of magnitude more sensitive than anything we have so far.
indoordin0saur 1y ago
You can look through a telescope and the actual light from the stars will be hitting your retinas, so you can answer this question for yourself! For most things like nebula and galaxies the shapes can be made out easily but often the colors are absent or muted because our eyes' color cones don't do as well in low-light as a monochromatic rods. This is similar to how if you have ever seen the aurora the colors are hard to perceive but if you use a camera they pop out a lot more. There's a big range though and it depends on the intensity of light from the object. There are certainly nebulas and other objects out there with enough light intensity that our eyes can naturally perceive the color. The other thing to keep in mind is that people's night vision and ability to perceive color in low light is highly variable, much like how our visual acuity (near/far sightedness) vary greatly by individual and worsen somewhat with age.
cruffle_duffle 1y ago
Another thing not mentioned is all the stuff further away gets redshifted down into IR thanks to the universe expanding. So while the original output might have been in the visible part of the spectrum its wavelengths have now been stretched out to something your eye can no longer see. If you want to see all the cool shit 4 billion light years away, you are gonna have to get those retinal IR implants you keep asking for each Christmas installed.
m463 1y ago
depends on how close you are to say, the sun or a supernova. also, without an atmosphere or magnetic field or day/night your eyes might not have as much longevity due to no shielding from harmful radiation/uv/etc.

cconstantine 1y ago

For the vast majority of things in the sky, they'd see black. This stuff is incredibly dark, and we need hours of exposure time to get enough signal. Even after hours of exposure the raw stacked frame is a black field with some pinpoints of lights. The exception to this is stuff in our own solar system.

hnuser123456 1y ago

Well, some of the densest, nearest, most interesting structures are right behind the rest of the Milky Way, which causes up to 30 magnitudes of extinction in visible light, but deeper IR and UV passes through much more easily. I think a better way to describe the issue is that much of the structure of the cosmos is only visible in non-visible wavelengths, so while calibrated, accurate visuals "like you were in a safe glass bubble" is a good category of astrophotography to continue to refine, it's a tiny slice of what's emitting electromagnetic radiation that's worth visualizing. And if cameras can convert invisible colors into visible ones, that's a blessing of a capability.

yig 1y ago
Can we infer what that visible light would look like unobstructed and with appropriate intensity to activate our eyes' cones?
- hnuser123456 1y ago
  Not necessarily, various objects can look completely different in different wavelengths and it's not really possible to interpolate without taking a picture of each part of the spectrum.
jacobr1 1y ago
Even in the case of the Milky Way blocking the light, we could probably do the math to estimate would an observer would see if they were outside the Milky Way, interpolating from the observed IR/UV and some model of the visible spectra would be be without the local interference. Or is that infeasible in some way? Certainly some phenomena just don't have much visible light of interest - so shifting the the spectra is inherently necessary in those cases and is thus inherently subjective.
- hnuser123456 1y ago
  Not necessarily, various objects can look completely different in different wavelengths and it's not really possible to interpolate without taking a picture of each part of the spectrum. The Milky Way and the entire local group of galaxies are flowing towards the superclusters located directly on the opposite side of the galaxy, and there's huge (thousands of light years) clouds of gas and "dust" (supernova molecular feces) that are like actual, thick, opaque storm clouds that form a donut around the galaxy, so it's impossible to "see" where we're headed except for the the X-rays and mid-infrared that doesn't interact with the huge clouds. And we won't be able to until we can leave the plane of the Milky Way's disk, or we build a telescope that is 2 dozen orders of magnitude more sensitive than anything we have so far.

indoordin0saur 1y ago

You can look through a telescope and the actual light from the stars will be hitting your retinas, so you can answer this question for yourself! For most things like nebula and galaxies the shapes can be made out easily but often the colors are absent or muted because our eyes' color cones don't do as well in low-light as a monochromatic rods. This is similar to how if you have ever seen the aurora the colors are hard to perceive but if you use a camera they pop out a lot more. There's a big range though and it depends on the intensity of light from the object. There are certainly nebulas and other objects out there with enough light intensity that our eyes can naturally perceive the color. The other thing to keep in mind is that people's night vision and ability to perceive color in low light is highly variable, much like how our visual acuity (near/far sightedness) vary greatly by individual and worsen somewhat with age.

cruffle_duffle 1y ago

Another thing not mentioned is all the stuff further away gets redshifted down into IR thanks to the universe expanding. So while the original output might have been in the visible part of the spectrum its wavelengths have now been stretched out to something your eye can no longer see. If you want to see all the cool shit 4 billion light years away, you are gonna have to get those retinal IR implants you keep asking for each Christmas installed.

m463 1y ago

depends on how close you are to say, the sun or a supernova. also, without an atmosphere or magnetic field or day/night your eyes might not have as much longevity due to no shielding from harmful radiation/uv/etc.