@Miaelou_VT The light is the heat. It's a byproduct of the suns's fusion reactions that produce a broad spectrum of radiation including the visible spectrum we see as light.
I finally have all 1.2 million raw image files from my latest mission to ISS! Here is a sample of one of my favorite Milky Way photos, taken from the Cupola with Nikon Z9, Arri Zeiss 15mm lens, T1.8 with custom sidereal drive that cancelled out star motion relative to our orbit.