Office for Astronomy Outreach

100 hours for astronomy

100 Hours of Astronomy

Each year, the Office for Astronomy Outreach (OAO) organises 100 Hours of Astronomy, a global event that invites people of all ages and cultures to connect with the night sky and the science behind the stars. This event aims to spark scientific curiosity and bring astronomy to communities worldwide, from bustling cities to the most remote areas. Through public observation events, workshops, talks, and educational activities, 100 Hours of Astronomy facilitates shared experiences that inspire exploration of the Universe and encourage reflection on our place within it.

Since its inception during the International Year of Astronomy 2009, 100 Hours of Astronomy has shown that astronomy connects us to the stars and one another, becoming a universal celebration of knowledge and cooperation. By reminding us that we all look up at the same sky, we aim to foster community bonds, promote interest in scientific education, and cultivate a sense of global belonging. Anyone interested in engaging the public with astronomy can propose an event and join this international network, making 100 Hours of Astronomy a truly inclusive and collaborative celebration.

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100 Years of the Planetarium

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From 2 to 5 October 2025, join the IAU Office for Astronomy Outreach for a 100-hour, round-the-clock, round-the-globe celebration of astronomy. This event aims to engage as many people as possible—from children to seniors—with the sky and our astronomical surroundings.

Planetariums have long been a source of inspiration for children and adults alike. In 1923, the first planetarium projector was invented in Jena, Germany, and two years later, the first planetarium opened its doors in Munich. Between 2023 and 2025, the world celebrates the centennial of the planetarium and the countless ways planetariums have impacted society. This year, the IAU Office for Astronomy Outreach (OAO) will team up with the International Planetarium Society (IPS) to continue the legacy of 100 Hours of Astronomy and celebrate 100 Years of the Planetarium!

With the increasing levels of light pollution worldwide, it is impossible to experience a truly dark sky in many places. Planetariums are then dark sky oases: sanctuaries for night sky enthusiasts, exposing the public to the Universe. Even in locations where skies are protected from city lights, planetariums are still powerful educational tools for understanding the Universe and our place within it. This year, we encourage everyone to visit their local planetarium—small, large, mobile, or stationary—and immerse themselves in the wonders of our Universe.

The OAO and IPS hope to activate planetariums worldwide to participate in this programme.

How to participate?

  1. Plan a special event during 100 Hours of Astronomy or identify a pre-existing event you'd like to highlight during this time.
  2. Download the media kit.
  3. Promote your event alongside 100 Hours of Astronomy using the hashtag #100HoursOfAstronomy!

This Year's Events and Activity Ideas

Coming soon!

OAO Outreach Activity Toolkit

This toolkit compiles crowdsourced astronomy outreach activities that can be implemented during one of the IAU Global Outreach Events.

We invite you to experiment with the featured activities and share your ideas by contributing to the Toolkit!

Share your event with the world

We encourage you to share your events and participate in this year’s 100 Hours of Astronomy! If your event is open to the public, please leave enough information for people to get involved—both in person and online!

While the 2025 100 Hours of Astronomy theme is “100 Years of the Planetarium,” the spirit of this programme is to bring people together through the awe astronomy inspires in us all. We hope people worldwide will spread their love for astronomy, whether under the dome or our shared sky!

The submissions must be written in English. If you cannot translate the information for your event, please use an online translator like Google Translate or DeepL.

Please note that we may copy-edit some content if needed.

Share your event with the world

Calendar of Astronomy events

To highlight all the amazing activities happening around the globe, we will promote a calendar of events displayed on a world map and our social media channels.

More Information

All events must respect the general guidelines of the IAU Global Outreach initiatives, which promote the key role of astronomy for the betterment of science and society through collaboration and with a spirit of respect, tolerance, and peace.

If you need to change your events already on the calendar, please email the IAU Office for Astronomy Outreach Team via public@...Click to show with the subject line “100 Hours of Astronomy Calendar 2025 - Update”.If you cannot submit through this form, please email the IAU Office for Astronomy Outreach team via public@...Click to show with the subject line “100 Hours of Astronomy Calendar 2025 - Update”.