Shortcut Navigation:

The Arthur Ross Terrace will be closed this morning, Tuesday, October 21, for a private cultural observance. You many observe smoke and/or fire coming from the Terrace at that time. The FDNY has been notified in advance, and all safety precautions are in place. The Terrace will reopen at 1 pm.

Cosmic Microwave Background Discovered 50 Years Ago Today

News posts

Fifty years ago today, two astronomers made a discovery that forever changed our understanding of the universe. 

On May 20, 1964, American radio astronomers Robert Wilson and Arno Penzias were working at the 50-foot-long Horn Antenna in Holmdel, New Jersey, at what was then Bell Telephone Laboratories. 

Dark Universe Bell Labs Establishing Shot

Scenes in Dark Universe were shot on location at New Jersey's Bell Labs.

© AMNH/R. Mickens


When they pointed the antenna at empty patches of sky, the researchers stumbled on a low-level hiss. The constant noise would turn out to be cosmic radiation—cosmic microwave background—evidence for the Big Bang theory of the beginning of the universe.

The Big Bang theory suggests that the universe was once hotter than the surface of the Sun and emitted bright light. If this was the case, we should be able to detect the radiation from that early expansion of the universe—which Wilson and Penzias were the first to do, on that May day 50 years ago.

Learn more about this monumental discovery in a video: 


Learn more about cosmic microwave background and other pivotal discoveries about our universe in Dark Universe, the new Space Show narrated by Neil deGrasse Tyson.

American Museum of Natural History

Central Park West at 79th Street
New York, NY 10024-5192
Phone: 212-769-5100

Open daily from 10 am - 5:45 pm
except on Thanksgiving and Christmas
Maps and Directions

Enlighten Your Inbox

Stay informed about Museum news and research, events, and more!