Did You Know: The Expanding Universe

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Did you know that the universe is expanding?

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, NASA Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory, and Sonoma State University.
  • Animation of universe expansion: STScI/Leah Hustak 
  • Visualization of CANDELS Ultra Deep Survey Field: NASA, ESA, F. Summers, J. DePasquale, G. Bacon, and Z. Levay (STScI)
Written by Leah Ramsay
Designed by Craig Anderson, Leah Hustak, and Dani Player
Editorial and design input from Claire Blome, Margaret W. Carruthers, Dr. Brandon Lawton, and Timothy Rhue II
Music courtesy of Music for Non-Profits


 Text, Did you know? The Expanding Universe 

The universe is expanding. 

Animation illustrates the expansion of the universe from Big Bang to now. Text, Once it was assumed the size of the universe was stable and unchanging. 

In the 1920s astronomers demonstrated that galaxies are moving away from each other - that the universe is expanding. 

Our understanding of the universe was turned upside down. 

Scientists developed the big bang theory to explain how the expansion of space and time began. 

Cross-cut to a star field view. 

More surprising discoveries followed. 

In the 1990s astronomers discovered that the expansion of the universe is accelerating. 

The unknown force causing this acceleration is called dark energy. 

Scientists are working to understand dark energy and the expansion of the universe. 

The answers may lead to yet another dramatic shift in our understanding of the universe.