On 2–5 October, 2025, Zooniverse volunteers will join astronomy enthusiasts worldwide in celebrating 100 Hours of Astronomy, a global festival of skywatching and science. We’re aiming for 15,000 classifications in just four days, and you can help us get there by joining the Zooniverse 100 Hours of Astronomy Community Group and exploring astronomy projects on Zooniverse. Try Rubin Comet Catchers to help scientists hunt for icy bodies in our Solar System, Cloudspotting on Mars: Shapes to study Martian clouds and their role in the Red Planet’s atmosphere, or Galaxy Zoo to explore galaxies in dazzling JWST images! Every classification opens the door to real discoveries – and toward our shared goal.

100 Hours of Astronomy, organized by the International Astronomical Union’s Office for Astronomy Outreach, connects communities around the world through stargazing, workshops, and shared wonder of the cosmos. This year, Zooniverse makes it possible to join in from anywhere with support from the Adler Planetarium; celebrating discovery not just by enjoying the night sky but through engaging with the data of the Universe itself. We’ll share collective impact via the group stats and highlights throughout the event. Thank you for participating and expanding the connections of our global community!