COMPARE THE EARTH'S PLACE IN THE UNIVERSE TO OTHER CELESTIAL BODIES

Finding our place

You probably already know many things about the universe, but let's quickly review the basics. By definition, the universe includes anything that exists anywhere. In other words, if I asked you to name five things that exist in the universe, you would be right as long as you named any five things that actually exist.

Within the universe are many galaxies. Galaxies are clusters of stars. As you know, the sun is a star and it belongs to a galaxy called the Milky Way, which is the galaxy we live in. Galaxies are huge, but most are so far away from us that objects which look like individual stars to the naked eye are really billions of stars clumped together in a galaxy.

Our sun is just one medium-sized star in the Milky Way. The sun and its eight orbiting planets make up our solar system. An orbit is the path that an object makes while revolving or circling another object. Each of the planets has its own path, or orbit, around the sun. We also call an orbit a revolution. Some of the planets orbit, or circle, the sun very quickly and some move slower. In addition to orbiting around the sun, the planets also rotate. This means they spin on their axes, much like a top spins. One rotation is the amount of time it takes for a planet to spin around once on its axis. Some planets spin quite fast and for others the rotation is much slower.

Things to remember:

1. The universe includes anything that exists anywhere.
2. Galaxies are clusters of stars.
3. Our galaxy is the Milky Way.
4. The sun is just one medium-sized star in the Milky Way.
5. The sun and its eight orbiting planets make up our solar system.
6. An orbit is the path that an object makes while circling another object.
7. A rotation is the time it takes for a planet to spin on its axis.
8. Revolution is another name for orbit.

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