Intro to Science

2. A force of attraction between objects that is due to due to their masses.
5. Empty areas in space.
9. A galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile.
10. A dense concentration of galaxies.
11. A large collection of stars, gas, and dust that is held together by gravity.
12. A galaxy that does not have a regular shape, like a spiral or an elliptical galaxy.
13. The process by which nuclei of small atoms combine to form a new, more massive nucleus; the process releases energy. (2 words)
16. A mixture of gases that surround a planet moon or space object.
20. The name given to 2 probes launched by NASA to study outer Solar System and eventually interstellar space.
21. A large celestial body that is composed of gas and emits light.

1. A small galaxy that contains as few as 100 million stars.
3. An optical instrument designed to make distant objects appear nearer.
4. A spherical body that orbits the sun.
6. A collection of large and small bodies that orbit our central star, the sun. (2 words)
7. A galaxy in which the stars and gas clouds are concentrated mainly in one or more spiral arms.
8. A group of 10 or more galaxy clusters.
14. Space and all of the energy and matter in it.
15. A large galaxy that contains hundreds of billions of stars.
17. The path of a celestial body or an artificial satellite as it revolves around another body.
18. A telescope orbiting Earth that was launched in 1990.
19. A smaller body that orbits a planet.