Life On Earth

4. part of Earth in which life exists including land, water, and air or atmosphere
6. instrument for measuring speed
12. a paper copy of a document made with a special machine
13. arrangement of events in time
14. Scientific study of interactions between organisms and their environment
16. A characteristic or constant factor, limit
18. the study of the earth's physical and cultural features
19. attractive in pictures or photographs

1. having the same shape, size, and position on both sides of a dividing line
2. arranged in order of time
3. having a form composed of one or a number of simple shapes, such as triangles, squares, or circles
5. to cause to happen at the same time
7. a particle of light
8. science dealing with the earth's history as recorded in rocks
9. the study of weather
10. a close relationship of mutual dependence
11. A model of the universe in which Earth is at the center of the revolving planets and stars.
12. a device that converts light energy into electrical energy
15. An instrument that measures distance traveled by a vehicle
17. continuing for a long time