# Zwicky's Dark Matter: The Universe's Greatest Hidden Mystery
Published: January 30, 2026
Duration: 1:57
# This is your Astronomy Tonight podcast.
Good evening, stargazers! Welcome back to another episode of Astronomy Tonight, where we explore the cosmos and celebrate the celestial events that have shaped our understanding of the universe.
Today, we're highlighting a remarkable event that occurred on **January 30th, 1933**—nearly a century ago—when **Fritz Zwicky made his groundbreaking announcement about "dark matter."**
Now, here's where it gets fascinating: Zwicky, a Swiss astronomer working at Caltech, was studying the Coma Cluster—a collection of about 1,000 galaxies bound together by gravity. When he calculated how fast these galaxies were m...
Good evening, stargazers! Welcome back to another episode of Astronomy Tonight, where we explore the cosmos and celebrate the celestial events that have shaped our understanding of the universe.
Today, we're highlighting a remarkable event that occurred on **January 30th, 1933**—nearly a century ago—when **Fritz Zwicky made his groundbreaking announcement about "dark matter."**
Now, here's where it gets fascinating: Zwicky, a Swiss astronomer working at Caltech, was studying the Coma Cluster—a collection of about 1,000 galaxies bound together by gravity. When he calculated how fast these galaxies were m...