Astro, A.K.A. Experiment 552, is an illegal genetic experiment created by Jumba Jookiba. He is designed is designed to absorb light. His one true place is putting on a shadow puppet show.
Experiment 552 was the 552nd genetic experiment created by Jumba with Hämsterviel's funding. He is designed to absorb light (does so by finding the highest possible point that it can and starts to draw in all the light and absorbing it through his abdomen).
552 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
At an unknown point, 552 was activated, captured and named Astro.<
He makes it seem like its constantly night time even during the day.