10 Need-to-Know Things About the Universe:
- Edwin Hubble discovered that the Universe is in fact expanding and that at one point in time (14 billion years ago) the Universe was all collected in just one point of 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.
- Roughly 70 percent of the Universe is made of dark energy. Dark matter makes up about 25 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 and clusters of galaxies that make up the visible Universe are concentrated in a complex scaffold that surrounds a network of 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.
- There are planets around other stars in our galaxy and very likely around other stars in other galaxies within the Universe. More than 900 planets have been confirmed orbiting other stars, and thousands more are awaiting 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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