The Universe has been defined as ‘everything that exists, everything that has existed, and everything that will exist’. In other words, the Universe is all of time, space, and its contents. What is currently known about the contents of the Universe can be categorized into three types of substance: normal matter, dark matter, and dark energy.
Normal matter is everything comprised of atoms, including stars, planets, and human beings. Only a small portion of the Universe (approximately 1-10%) is normal matter.
Dark matter can’t be seen with current technology because it doesn’t emit or absorb light, but scientists know it’s there because its gravitational effects on the motion of galaxies and stars can be observed. It’s estimated that a quarter of the Universe contains dark matter.
Dark energy makes up approximately 70% of the Universe, but nothing much more is known other than it’s a mysterious cosmic phenomenon that affects the expansion of the Universe.
The size of the Universe is another mystery, and it’s believed it has neither an edge nor a center.
So…that’s a lot of unknowns, and you’re probably asking, “What do we know about the Universe?
During a 2008 interview, Dr. Neil deGrasse Tyson was asked “What is the most astounding fact you can share with us about the Universe?” His answer is recited in this short video, The Most Astounding Fact, from Max Schlickenmeyer.
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Astronomers know quite a lot about the history of our Universe, but there is one significant unknown — the cosmic dawn, a period of time when the first stars and galaxies were born and drastically changed it from darkness to first light. During the March 18 presentation, Glimpses of the Cosmic Dawn, Dr. Alex Ji will take you on a short tour of the early history of the Universe and explain how glimpses of the cosmic dawn era have recently been observed.
Live stream broadcast of Glimpses of the Cosmic Dawn is scheduled on Monday, March 18, 4-5:30pm EDT.
Programming Note: Sometimes it happens — scheduling changes or technical interruptions in the live broadcast. Please check back for live action updates, and take a look at the Live Stream Program Guide for more On2In2™ streaming info.
If you missed the May 7, 2018 live stream broadcast of Dark Energy and Cosmic Sound, there’s still time to watch a video recording as Dr. Daniel Eisentein (Professor of Astronomy, Harvard University & Director, Sloan Digital Sky Survey III) describes how sound waves scattered throughout the Universe have given scientists the most precise measures of the composition and history of the Universe. Just click/tap the “Watch Again” button on the media player below ↓
The formation of our Solar System was a chaotic collapse of gas and dust as well as catastrophic collisions between forming celestial bodies — a process that resulted in the Sun, planets, asteroids, and comets that exist today. Dr. Joseph Masiero, Scientist and NEOWISE Deputy-PI, NASA Jet Propulsion Lab, discusses how the asteroid families in the belt are the last remnants of those massive collisions, and provide a glimpse into the processes that have shaped our Solar System. If you missed the April 23, 2018 live stream broadcast of A Tale of Asteroid Families, there’s still time to watch a video recording of the event. Just click/tap the “Watch Again” button on the media player below ↓
Dr. Clifford V. Johnson is a professor in the Physics and Astronomy department of the University of Southern California, and he’s been awarded the Institute of Physics Maxwell Medal and Prize (2005) and a Simons Foundation Fellowship (2016). His research focuses on the development of theoretical tools for the description of the basic fabric of Nature in pursuance of an understanding of the origin, past, present and future of the Universe. Dr. Johnson is also the author of The Dialogues: Conversations About the Nature of the Universe*, a graphic, novel-style non-fiction book that uniquely brings the reader into conversations about exploring the Universe. It’s a fun read for the non-expert. On February 2, 2018, Dr. Johnson talked about his work and the book at the Griffith Observatory in Los Angeles, California. If you missed the live stream broadcast of the event, there’s still time to watch a video recording. Just click/tap the “Watch Again” button on the video player below ↓
Universe: Dark Energy, Dark Matter – NASA Science (contents of the Universe explained)
Questions and Answers: What is an atom? (defined & described in simple terms) The Thomas Jefferson National Accelerator Facility (Jefferson Lab)
The human body — what is it made of? (cells, molecules and atoms within the human body) Socratic.org (Anatomy & Physiology)
⇒ ⇒ NASA App (FREE to download for smart phones, tablets & digital media players) Includes a huge collection of NASA content, including images, videos on-demand, NASA Television, mission information, and much more.
⇒ ⇒ Digital Universe Atlas, a 3-D atlas of the Universe developed by the Hayden Planetarium of the American Museum of Natural History (FREE to view and download)
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Feature photo is courtesy of Unsplash CC0