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Stargazing Lecture

Friday, August 25, 2023
8:00pm to 10:00pm
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Cahill Center for Astronomy and Astrophysics
Galaxy Clusters Collide: The Most Energetic Events since the Big Bang
Emily Silich, PhD Candidate, Department of Astronomy, Caltech,
  • Public Event

Stargazing is dependent on clear weather, but lecture and Q&A happen regardless. Event will occur in-person, with lecture and Q&A additionally live-streamed on YouTube.

For remote viewers, the event will be live-streamed here:

8:00–8:45 p.m. - Public Lecture
8:45–9:45 p.m. - Panel Q&A and Guided Stargazing

Galaxies, like our own Milky Way, don't tend to live in isolation. When we scan our telescopes across the sky, we don't see a random scattering of galaxies throughout space. Instead, we see many dense regions where hundreds to thousands of galaxies exist in close proximity to each other, known as galaxy clusters. These clusters, surrounded by dark matter and extremely hot gas, are the largest and most massive objects in the universe bound together by their own gravity. So, what happens when two of these galaxy clusters collide? Some of the most energetic events in the universe — second only to the Big Bang itself! I'll discuss how studying these powerful collisions can answer exciting questions, from how structures in the universe form to the nature of dark matter itself.

About the Series

Stargazing Lectures are free lectures at a public level followed by a Q&A panel and guided stargazing with telescopes (weather permitting). All events are held at the Cahill Center for Astronomy and Astrophysics at Caltech and are Free and open to all. No reservations are needed. Lectures are 30 minutes; stargazing and panel Q&A last 60 minutes. Stay only as long as you want.

Stargazing is only possible with clear skies, but the lecture and panel Q&A take place regardless of weather.

For directions, weather updates, and more information, please visit:

For more information, please contact Cameron Hummels by email at [email protected].