About 13.8 billion years ago, the Big Bang gave rise to everything, everywhere, and everywhen—the entire known Universe. What caused the Big Bang? What happened that first moment at the beginning of ...

Center for Astrophysics | Harvard & Smithsonian scientists study galaxy formation and evolution in a variety ways: Looking for hidden structures and unusual stars that reveal the Milky Way’s history.

For the first 380,000 years or so after the Big Bang, the entire universe was a hot soup of particles and photons, too dense for light to travel very far. However, as the cosmos expanded, it cooled ...

Center for Astrophysics | Harvard & Smithsonian astronomers study star clusters in a variety of ways: Looking for exotic binary systems including black holes or neutron stars. Globular clusters are ...

Our modern understanding of gravity comes from Albert Einstein’s theory of general relativity, which stands as one of the best-tested theories in science. General relativity predicted many phenomena ...

Center for Astrophysics | Harvard & Smithsonian scientists study many different aspects of white dwarfs and neutron stars: Observing the way white dwarfs interact with other astronomical objects, ...

Everything you’ve ever seen or experienced on Earth was once a nebulous collection of floating gas and dust. Science is starting to understand how those particles came to take the forms you recognize ...

Matter and energy are the two basic components of the entire Universe. An enormous challenge for scientists is that most of the matter in the Universe is invisible and the source of most of the energy ...

The Milky Way is our galactic home, part of the story of how we came to be. Astronomers have learned that it’s a large spiral galaxy, similar to many others, but also different in ways that reflect ...

Understanding the cosmos involves both observation and theory. Observation provides real-world data about how stars, galaxies, and other objects in space behave. Theory connects that data together ...

Center for Astrophysics | Harvard & Smithsonian astronomers study star formation and star-forming regions in a variety of ways: Measuring magnetic fields in star-forming regions to understand their ...

All the atoms and light in the universe together make up less than five percent of the total contents of the cosmos. The rest is composed of dark matter and dark energy, which are invisible but ...