Yes, the overall color of the Universe today is certainly something like Cosmic Latte,
███. In the dawn of time, however, the color of the Universe may have been something like this,
███.
Why the change? Consider the JWST picture of starforming region NGC 602 in the Small Magellanic Cloud:
Look at the central cluster (which is slightly to the left of center in this image). You can make out a few bright stars there, perhaps ten. But look at the bee swarm of smaller stars surrounding the bright luminaries!
The big stars in the NGC 602 cluster are blue and bright. The small stars are, typically, red and faint. But the blue stars will die in a few million years: Death will come in just a handful of million years to the most massive blue stars, whereas the modest blue A-type stars will live for, perhaps, a few hundred million years at best.
But the red stars will hang on. The smaller they are, the longer they will last. The red stars are keepers. The blue stars are goners.
Every episode of star formation will create more small red stars than big blue stars. When a star cluster is newborn, the relatively few blue stars will outshine the the large numbers of red stars, because the blue stars are so much brighter.
But when the blue stars are gone, only the red stars remain. And the light of red stars, while not red, is certainly yellow. Because, yes, the "red" stars are yellow or yellow-orange, whereas our Sun is white or just a tad yellow-white.
The Universe used to be dominated by small starbursting galaxies shining brightly with blue light:
But over billions of years, huge populations of yellow stars have been built up, leading to galaxies like these:
There is a fun comparison between what the Milky Way looks like today and what it may have looked like 10 billion years ago:
I must say that I'm critical of the portrait of present-day Milky Way, because I think that we see far too much red hydrogen alpha here. In most Milky Way photos, we don't see much hydrogen alpha at all. Here is an example of what the Milky Way often looks like in photographs:
I should add that I really think that today's Milky Way is a fine example of Cosmic Latte!
So people get gray hair when they grow old. Star clusters and galaxies grow yellow.
Trumpler 5 Photocommunity Deutschland.png
Old yellow star cluster Trumpler 5.
Credit: Photocommunity Deutschland
Ann
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Cosmic Latte: The Average Color of the Universe
