# So where's this extra-galactic light coming from? **URL:** \ **Category:** Factual Questions\ **Created:** [December 12, 2020, 8:02pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920 "2020-12-12T20:02:16Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 13, 2020, 9:24pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/21 "2020-12-13T21:24:30Z")
To within the limits of resolution of your camera, and of the total number of photons you’re receiving. Take that Hubble Deep Field image I linked to-- That was taken with a very high-resolution camera, enough so that you can see both the galaxies and the gaps between them. And each galaxy was bright enough that each pixel of each galaxy received a great many photons (I don’t know specifically for that image, but I’d guess a few thousand). But now suppose, for instance, that scattered between those galaxies are isolated stars, that aren’t organized into galaxies. Each star is much less bright than a galaxy, so you’re getting many fewer photons per star. Many such stars, in fact, you might not get any photons at all from, and the few you get any from, it’ll usually only be one each. That’d just produce an overall haze of faint light, that you couldn’t pin down to any specific sources. Heck, you wouldn’t even be able to distinguish it from the noise in your instrument, except to the extent that you know very precisely how much noise your instrument has (but not where it is; if you knew that, it wouldn’t be noise). ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 13, 2020, 9:28pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/22 "2020-12-13T21:28:14Z")
> [@Squink](#): > > Mangetout, Space mighty be foggy enough to diffuse distant light sources beyond recognition. Understood, I mean, we know space is not completely empty, so there will be some scattering. I am only a layman, and it most likely means I am missing something, but this just sounds not-very-mysterious to me. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 13, 2020, 9:29pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/23 "2020-12-13T21:29:58Z")
> [@wolfpup](#): > > I’m reminded of the incident back in 2011 when a neutrino beam at CERN was apparently traveling faster than light. In that case few seriously believed it, but neither could anyone explain the observation. It eventually turned out that there were, not one, but two, sources of error. When the errors were eliminated the anomaly disappeared. The recent _phosphine on Venus_ flail is another example of “simple” errors in complex calculations leading to an apparent find that turns out to be an Oops. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 13, 2020, 9:38pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/24 "2020-12-13T21:38:08Z")
That one was even more anticlimactic. Most folks were assuming that there was in fact phosphine in Venus’ atmosphere, and just thought that there was some non-biological process that accounted for it. And really, in an environment like Venus, you’d expect to see a few unfamiliar chemical reactions. But no, it turns out it wasn’t even there at all. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [December 13, 2020, 9:48pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/25 "2020-12-13T21:48:51Z")
The [age of “Olber’s paradox”](https://en.wikipedia.org/wiki/Olbers%27_paradox#History) adds to the mystery here. ---
**Author:** ![CairoCarol](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cairocarol/32/3825_2.png) [@CairoCarol](https://boards.straightdope.com/u/CairoCarol)\ **Post date:** [December 13, 2020, 10:05pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/26 "2020-12-13T22:05:34Z")
When he closes it, the extra light will go away. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [December 13, 2020, 11:10pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/27 "2020-12-13T23:10:41Z")
Done. Is that better now? ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [December 13, 2020, 11:34pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/28 "2020-12-13T23:34:26Z")
Just lemme send out another Pluto probe and we’ll know in fourteen or fifteen years. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [December 14, 2020, 2:40am UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/29 "2020-12-14T02:40:21Z")
> [@Chronos](#): > > Most folks were assuming that there was in fact phosphine in Venus’ atmosphere, and just thought that there was some non-biological process that accounted for it. And really, in an environment like Venus, you’d expect to see a few unfamiliar chemical reactions. But no, it turns out it wasn’t even there at all. It wasn’t? [Latest I heard](https://www.nature.com/articles/d41586-020-03258-5), the concentration had been revised down, but there was no yet a conclusion that it wasn’t there at all. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 14, 2020, 2:45am UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/30 "2020-12-14T02:45:21Z")
Phosphine is very flammable. Maybe it burnt off and gave out a bunch of light…? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 15, 2020, 1:52pm UTC](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920/31 "2020-12-15T13:52:24Z")
> [@Mijin](#): > > It wasn’t? [Latest I heard](https://www.nature.com/articles/d41586-020-03258-5), the concentration had been revised down, but there was no yet a conclusion that it wasn’t there at all. Interesting. Thank you. And pretty up-to-date. The last I had read seems to say “pure artifact of post-processing math; no actual signal.” This suggests the situation is more nuanced than that. [Previous page](https://boards.straightdope.com/t/so-wheres-this-extra-galactic-light-coming-from/927920.md?page=1)