Just in time for February’s school vacation, Providence’s Museum of Natural History and Planetarium will offer a new exhibit and a new planetarium show beginning Saturday. “Dynamic Galaxies: Our Place in the Universe,” the new exhibit, focuses on the properties of galaxies, and what’s been learned about the universe from studying them. “Small Pieces of Glass: The Amazing Telescope” is a full-dome planetarium show that explores how telescopes have helped us understand our place in space and how they continue to expand our understanding of the cosmos.