1. Stars and Galaxies n Our sun is a star. n There are countless more like it in space.

2. n The sun is one of billions of stars that make up the Milky Way. n The Milky Way is a Galaxy. n A galaxy is a cluster of stars held together by the force of gravity.

3. n The stars in a galaxy are very far apart. n It may take several years for a spacecraft to reach other planets in our solar system. n It may take several centuries to reach other stars in our galaxy.

4. n Beyond the milky way there are other galaxies. n Scientists believe there may be as many as 100 000 million other galaxies beyond ours.

5. n Because gravity attracts them together, the stars in a galaxy are clustered. n This means there are vast expanses of nothing between different galaxies.

6. Stars and Galaxies n Our sun is a star. There are countless more like it in space. n The sun is one of billions of stars that make up the Milky Way. The Milky Way is a Galaxy. n A galaxy is a cluster of stars held together by the force of gravity. n The stars in a galaxy are very far apart. n Scientists believe there may be as many as 100 000 million other galaxies beyond ours. n Because gravity attracts them together, the stars in a galaxy are clustered. n There are vast expanses of nothing between different galaxies.