Betelgeuse is 642 light years away and we can easily see it with our naked eye. Which means it’s at the center of a vast sphere, thousands of light years across, entirely filled with its photons. Go anywhere in that sphere & look toward Betelgeuse & its photons will hit your eye.
Of course, the telescope shows us that each star’s “photon sphere” is actually much bigger still. And the fact that we can see galaxies billions of light years away means that galaxies emit photon spheres tens of billions of light years across.
The sheer volume of these spheres is unimaginable. Billions of cubic light years completely saturated with the photons of a single star (10^30 cubic light years or more for a galaxy). The number of photons it takes to fill these spheres is mind boggling.
Btw if you’re somewhere with good stars right now, Betelgeuse is Orion’s left shoulder.
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