Lance loves the night sky – and, since there was much less light pollution back in the day, there were billions more stars visible to him than there are to us now, and the gleaming strip of light that is the center of our Milky Way was much brighter and more easily distinguishable. So, of course, there’s a lot for him to love. He was taught the basics of astronomy / astrology ( they were considered the same at the time ) while he was being raised in Avalon, so he knows major constellations and stars. He also learned how to navigate with the night sky when he was on campaign with his father in Gaul. As a result, the stars are, in his eyes, a perfect mix of both the practical and the beautiful.
His Fairy blood doesn’t have as close a kinship with the stars as it does the sun and the moon, but it still gives him some small ability to know intrinsically which constellations appear in the sky during different parts of the year. As a result, his navigational skills are augmented over his more mortal-blooded counterparts, since he always knows which clusters of stars should appear where and at what time. They don’t influence his thoughts and emotions the way the length of the day or the phase of the moon do, however.