For a long time, there existed a question about why we didn't see a brighter sky. Because of the multitude of stars in our galaxy, and the multitude of galaxies in the known universe, coupled with the age of same, it was felt that we should be able to see starlight from every direction. Yet the sky is dark in most places. I think it was Edwin Hubble who gave an answer.

The universe is expanding, and the farther away stars and galaxies are the faster they are moving away from us. Because of the Doppler effect, the light from farther luminous objects is shifted into the infrared spectrum, which our eyes cannot perceive.

Move to the Shadowrun universe in which some metahumans have infrared(heat) vision. Now, not all of the infrared spectrum is associated with heat, but still, one would think that to those metahumans who have this ability, the night sky should be brighter than it is for those who do not.

New constellations, or better delineation of older ones? A general glow that can help/obscure heat vision out in the open?

Thoughts?

Yep, the night sky is probably a teensy bit lighter for people with infravision, but not enough to make a discernible difference. The reason the sky is dark is not that the light from other stars has changed to a longer wavelength, but that their light hasn't reached us yet.

Our star is 4.6 bn years old, or about a third of the age of the universe. The light from our star can only be seen at a distance of 4.6 bn light years in any direction, which only accounts for a fraction of the size of the entire universe. If the universe would stop expanding for, say, 15 billion years, the night sky might well be lit up by the light of (dead) stars!

To expand a bit on Lionesque's answer, starlight does of course show a redshift, just not enough to shift most of it out of the visible spectrum.


There is something else in the sky which does show a lot more redshift, namely the cosmic background radiation...however, that is actually shifted past infrared, into microwave territory. Poor infrared

Here's a link that pulls the above together in a quickie answer.

More detail here.

And here is a rabbit hole to avoid unless you are into astronomy.

It's difficult to extract from all of this what the effect would be on metahuman heat vision. I don't think I want to get into the math necessary to do so.

Overall the amount of IR light in the environment (and that includes night time skies even with clouds) "obviously" is enough to improve lighting situation to the degrees that the visual modifiers in SR say it does. I'd leave the rest to individual imagination of players ... with one particular note however: Don't imagine blurry Robocop- / Predator-esque false color perception for either natural or technological sight but rather look at the results of IR photography instead.

Or you could look at a photo of the night sky that was indeed done with an IR camera:

https://i.imgur.com/o0H04Gw.jpeg