‘100 Hours of Astronomy’ celebrates 100 years of the planetarium

From Oct. 2–5 2025, the International Astronomical Union Office for Astronomy Outreach (IAU OAO) and the International Planetarium Society (IPS) will team up to celebrate the 100th anniversary of the first planetarium. Image Credit: IAU OAO

Key Takeaways:

The International Astronomical Union Office for Astronomy Outreach (IAU OAO) and the International Planetarium Society (IPS) will jointly host "100 Hours of Astronomy," a global event from October 2-5, 2025, celebrating the centennial of the first planetarium.
The event will feature two main components: a 360° livestream of the planetarium show "Big Astronomy" on October 2nd, followed by a talk on the Vera C. Rubin Observatory, and a 24-hour continuous stream from the Akashi Municipal Planetarium in Japan on October 4th, showcasing various planetariums worldwide.
The event aims to highlight the importance of planetariums in fostering global unity and scientific curiosity, encouraging participation from planetariums of all sizes and types.
Community engagement is encouraged through brainstorming event ideas, advertising on the OAO Astronomy Engagement Events Calendar, and social media promotion using designated hashtags.

From Oct. 2–5 2025, the International Astronomical Union Office for Astronomy Outreach (IAU OAO) and the International Planetarium Society (IPS), two of the world’s leading organizations dedicated to public engagement with astronomy, will team up to celebrate the 100th anniversary of the first planetarium. To mark the occasion, the organizations will deliver a 100-hour marathon of astronomy events and activities taking place across the world.

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.

During this year’s edition of 100 Hours of Astronomy, the IAU OAO and IPS will host two main events: Big Astronomy, Big Aspirations and 24 Hours of Planetariums. More information is included below, and additional details and registration forms will be available on the IAU OAO and IPS websites in the coming months.

Oct. 2: 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. After the show, Ardis Herrold (Rubin Observatory) will present 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 follow.

Oct. 4: 24 Hours of Planetariums

Planetariums – large, small, mobile, stationary, and handmade – 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 theme for 100 Hours of Astronomy 2025 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

More information will be posted on the OAO and IPS websites in the coming months.

More Information

The IAU is the international astronomical organization that brings together about 13,000 distinguished astronomers from around the world. Its mission is to promote and safeguard the science of astronomy in all its aspects, including research, communication, education and development, through international cooperation. The IAU also serves as the internationally recognized authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world’s largest professional body for astronomers.

The IAU Office for Astronomy Outreach (OAO) is a joint project of the International Astronomical Union (IAU) and the National Astronomical Observatory of Japan (NAOJ). The mission of the OAO is to make astronomy accessible to all through open-access astronomical information and quality astronomy communication. The OAO manages the network of IAU National Outreach Coordinators (NOCs) who carry out this mission on a global scale through the OAO public engagement initiatives. Through a series of professional development programming, the OAO ensures that astronomy communicators have access to the resources and training they need to best serve their communities.

The International Planetarium Society is a global association of planetarium professionals. Its nearly 500 members come from 50 countries, representing schools, universities, museums, and public facilities. The goal of IPS is to support the sharing of ideas through conferences, publications, and networking. Our vision is to be a creative and supportive resource for innovation, advancement, and cooperation among planetariums. Our mission is to provide the planetarium community with professional development, science literacy and humanities awareness, innovative ideas, and partnerships to enhance the world’s appreciation of our universe. We also value science as a way of knowing, inclusivity of and respect for cultures, openness to new ideas, service excellence and leadership in our field.