A color episode would be nice, not that they are not all colorful, of course.
A little history of it; perhaps things like the cyanometer and climbing mount Chimborazo in Ecuador (world's tallest mnt. back then), Newton's refrangibility of light, Goethe's views, etc.
Then the color emission lines as the green in OIII, hydrogen lines, etc. This should expand on Episode 16.
Some history from Brucke, Tyndall, Rayleigh to lead us to our blue sky and yellow Sun.
And, regarding the latter, I have a climax suggestion....
[Added: I wanted to also mention false color and its efficacy in astronomy. Also, as seen from space, the true color of some objects: Some T-class stars might look maroon (crimson for some of our Alabama friends
), some red giants will be more orange or golden, and most white dwarfs will probably look bluish white. GMCs will be gray but some early accretion disks might come in several colors, due to the proximity of hundreds of nearby stars, including the big bluish-white ones.]