To whet your appetite and keep your writing fingers limber, take a good look at the photo, or let a prompt settle in your mind. Set a timer for a reasonable amount of time, be that five, fifteen, or thirty minutes. Then start writing.
Tell the story of people using this map to navigate the galaxy. Or write about people who come to the surface, after living their whole lives underground, to see their first starry night.
What was your experience with stars when you were a child? Did you have a favorite constellation? Did you often wish upon a star? What do you feel when you gaze up at them now?
Write about the constellations that are visible in the sky this time of year where you live. What are the stars that make them up? How were they named?