From 2 to 5 October 2025, the International Astronomical Union Office for Astronomy Outreach (IAU OAO) and the International Planetarium Society (IPS), two of the world’s leading organisations dedicated to public engagement with astronomy, will team up to deliver a 100-hour marathon of astronomy events and activities dedicated to the 100th anniversary of the first planetarium.
The marathon event, 100 Hours of Astronomy, is run annually by the IAU Office for Astronomy Outreach to encourage people from all over the world to unite under one sky. This year, the IAU OAO partnered with IPS to highlight the legacy and importance of planetariums for fostering our sense of global togetherness and curiosity in the wonders of our Universe.
The IAU OAO and IPS will host two main events during 100 Hours of Astronomy: Big Astronomy, Big Aspirations and 24 Hours of Planetariums. More information is included below, but additional details and registration forms will be available on the IAU OAO and IPS websites in the coming months.
2 October: Big Astronomy, Big Aspirations
100 Hours of Astronomy will begin with a 360° YouTube livestream of the planetarium show, Big Astronomy. This show highlights the diversity of people who work at some of the most important sites for modern astronomy and their careers. Ardis Herrold (Rubin Observatory) will follow with a talk entitled “The NSF–DOE Vera C. Rubin Observatory – The Transformative Years”, discussing the next generation of ground-based astronomy. All are welcome to join this hour-long online event and engage with speakers, creators and audiences worldwide! Exact times and details to come.
4 October: 24 Hours of Planetariums
Planetariums – large, small, mobile, stationary, and hand-made – are important cultural and educational centres for their communities. The OAO and IPS want to show the world the unique view from inside your planetarium and give you and your team global recognition. Planetariums are invited to sign up for our 24-hour continuous event that we will stream live from the Akashi Municipal Planetarium in Japan. Whether it be a quick hello with your audience or a longer message for the world, the OAO and IPS hope you will participate in this event to demonstrate the connection everyone has to understanding our place in the Universe. The organisations jointly aim to make this as high-impact and low-cost as possible, ensuring all planetariums can get involved.
While the 2025 100 Hours of Astronomy theme is “100 Years of the Planetarium,” there are many ways to celebrate astronomy. Here’s how:
- Brainstorm ideas for an event with your community.
- Advertise your event on the OAO Astronomy Engagement Events Calendar.
- Tag the IPS and OAO in your social media posts using the hashtags #100HoursofAstronomy, #100YearsofthePlanetarium and #IAUOutreach