10 Need-to-Know Things About the Universe:
- Edwin Hubble discovered our universe is expanding. About 14 billion years ago, the universe was compressed into a single point in space.
- There are believed to be at least a hundred billion galaxies in the universe. A galaxy is full of stars: Our sun is just one of at least a hundred billion stars in our own Milky Way galaxy, and each of those stars could have their own planetary system.
- About 68 percent of the universe is made of dark energy. Dark matter makes up about 27 percent. The rest – everything on Earth, everything ever observed with all of our instruments, all normal matter adds up to less than 5 percent of the universe.
- We now know that our universe has a foamy structure. The galaxies that comprise the observable universe are concentrated in vast sheets and filaments surrounding enormous cosmic voids.
- The Milky Way galaxy is in the Local Group, a neighborhood of about 30 galaxies. Our nearest major neighboring galaxy is called Andromeda.
- More than 1,000 extrasolar planets (or exoplanets) planets have been confirmed. There are thousands of potential exoplanets await discovery confirmation.
- Other planetary systems could have the potential for life, but no signs have yet been found beyond Earth.
- Two-thirds of the galaxies within the Universe are similar to the Milky Way galaxy, in that they are spiral-shaped. The remaining third have elliptical shapes, and a few have unusual shapes like toothpicks or rings.
- The Hubble Space Telescope observed a tiny patch of sky (one-tenth the diameter of the moon) for 11.6 days and found approximately 10,000 galaxies of all sizes, shapes and colors.
- Black holes are not empty spaces in the Universe. A black hole is a great amount of matter packed into a very small area, which results in a gravitational field so strong that nothing -- not even light -- can escape.
Editor's Note: This page provides a brief overview of our Universe. For a comprehensive look at the Universe, visit NASA's Astrophysics Division.
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