Celestia is an open source application for visualizing the universe across scales ranging from human-sized to galactic. Users can smoothly zoom out from the Earth’s surface to distant galaxies and set the simulation time to observe the universe in the past, present or future. Since the project began in 2001, contributors have continued to adapt more and more data to include in Celestia’s model of the universe. Celestia has gained popularity among educators, who use it to demonstrate a variety of astronomical phenomena and convey a sense of humanity’s place in the universe. The program is accurate enough that it is also used within space agencies for mission visualization.