Nature and the universe

2. medium in degree; not extreme or intense
5. the loud noise that follows a flash of lightning, caused by the sudden expansion of air heated by the lightning
8. a small invertebrate animal that has six legs and a body divided into three main parts
10. an artificial body placed in orbit around the Earth or another planet in order to collect information or for communication
12. a prolonged period of excessively hot weather
13. a group of living organisms consisting of similar individuals capable of exchanging genes
15. to reuse or process (waste or materials) in order to produce something new
16. the rural areas outside of cities and towns, typically with farmland, forests, and small settlements
17. to keep something in its original or existing state; to protect or maintain
19. a bright flash of light in the sky caused by electricity discharging between clouds or between a cloud and the ground

1. animals that live in their natural habitats, especially in the countryside, rather than in captivity or in urban areas
3. a prediction of what the weather will be like in the near future
4. a warm-blooded animal that has hair or fur, feeds its young with milk from mammary glands, and typically gives birth
6. to free or deliver from confinement, danger, or difficulty
7. to find the exact position or place of something
9. waste material, such as paper, cans, and bottles, that is disposed of improperly, as in public places
11. the natural world and physical surroundings in which people, animals, and plants live
13. system the sun and the planets, moons, and other objects that orbit around it
14. the point or place where something begins, arises, or is derived
18. a species that has died out completely and no longer exists anywhere in the world