Timeline for Approximately what percent of the sky has nothing in it?
Current License: CC BY-SA 4.0
20 events
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| Feb 4, 2023 at 16:28 | comment | added | Todd Wilcox | @ProfRob I don’t think I understand your comment. The subject in question is a computer image analyzed by Johnathan Reez using RGB hex values as a substitute for actual telescope data. In this image, some pixels do have the hex value of #000000, or 0, 0, 0 (R, G, B). The total brightness ("distance from black") of hex color #010000 is something like 20 times less than the brightness of hex color #00080D. We’re attempting to explain that the criterion for "close to black" that Jonathan Reez used doesn’t seem useful. | |
| Feb 4, 2023 at 15:58 | comment | added | ProfRob | @ToddWilcox what is "black" in the picture does not mean zero flux, it is just where someone has set the zero point of the colour scale/contrast. You would need to analyse the science images (and none of the pixels will have zero signal). | |
| Feb 4, 2023 at 14:42 | comment | added | Todd Wilcox | @JonathanReez #010000 is closer to black than #00080D, and wouldn’t have shown up in your search. | |
| Feb 4, 2023 at 11:35 | comment | added | ProfRob | @nick01200 my response is now included as an edit. | |
| Feb 4, 2023 at 11:34 | history | edited | ProfRob | CC BY-SA 4.0 |
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| Feb 4, 2023 at 11:09 | comment | added | nick012000 | @ProfRob No? I'm just saying that if you draw a line out from the Earth to the edge of the observable universe, there's going to be some spots where there isn't anything between the two, even if there would be something if you drew the line out to infinity. | |
| Feb 4, 2023 at 11:07 | comment | added | ProfRob | @nick012000 you are labouring under the misapprehension that brightness is only determined by distance. Astronomical objects have a many order of magnitude range of intrinsic luminosities, and there are more of the less luminous things. | |
| Feb 4, 2023 at 11:02 | comment | added | nick012000 | "That is an accurate summary." It's not possible to actually set the depth of view to infinity, though, because there's an edge to the observable universe? | |
| Feb 3, 2023 at 23:27 | comment | added | Stack Exchange Supports Israel | @JonathanReez ... you were still searching for blue pixels with absolutely no red and only a little green | |
| Feb 3, 2023 at 23:27 | comment | added | JonathanReez | @user253751 I know, this was a typo, I meant to write #000*** | |
| Feb 3, 2023 at 23:25 | comment | added | Stack Exchange Supports Israel | @JonathanReez that isn't how hex colour codes work. You were searching for blue pixels with absolutely no red and only a little green. | |
| Feb 3, 2023 at 23:24 | comment | added | Stack Exchange Supports Israel | @Valorum in fact, they actually did do that. en.wikipedia.org/wiki/… - looks to my eye like it has less galaxies per pixel | |
| Feb 3, 2023 at 22:55 | comment | added | Loren Pechtel | But those objects are limited by the pixel size of the sensor (and implicitly, also, by the resolution of the lens.) In practice you can't have every line terminating in a star because that would make the night sky glow with the brightness of the surface of a star. In practice the vast majority of the sky must truly have nothing. | |
| Feb 3, 2023 at 7:26 | history | edited | ProfRob | CC BY-SA 4.0 |
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| Feb 3, 2023 at 6:58 | comment | added | Michael | Stars and galaxies in the photo look much bigger and “solid” than they are. A galaxy in the photo looks like a solid disc hundreds of thousands of light years wide. | |
| Feb 2, 2023 at 21:30 | comment | added | JonathanReez | After increasing contrast to 100% (to reduce artifacts), ImageMagick says that there are 921,600 pixels in that image, of which 9722 are entirely black, so only 1% is pure black. If I instead look for pixels that are close to black (by checking if the color RGB value starts with #000), there's 58144 close to black pixels or #00080D or 6.3%. | |
| Feb 2, 2023 at 20:49 | comment | added | Valorum | If I fpcus on one of the black bits in the Hubble Ultra Deep Field for long enough with my Super-Double-Hubble Ultra Ultra Deep Field experiment, would I find that all those black bits are actually filled with stars and galaxies? | |
| Feb 2, 2023 at 12:39 | vote | accept | Him | ||
| Feb 2, 2023 at 12:33 | history | edited | ProfRob | CC BY-SA 4.0 |
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| Feb 2, 2023 at 12:24 | history | answered | ProfRob | CC BY-SA 4.0 |