While he works in Processing, not p5.js, @HackinHarry has done a lot of work on this forum (and the old one) on interactive star charts / astronomy sims.
If you search this or the old forum for “solar” you will also find lots of solar system sims. They aren’t for displaying skies, but sometimes involve related concepts like timed rotations.
Other key terms: skybox, skyphere. In essence, drawing a sphere centered on the camera, putting a texture on it, and then correctly rotating it.