Across
- 4. A space without air, gas, or other matter.
- 7. The name for a “pulsating star.
- 8. Some scientists consider it to be a fourth state of matter.
- 9. The most common element in water.
- 11. This German discovered the X-ray.
- 12. Physicist Benjamin Thompson is associated with this phenomenon.
- 15. The ocean that receives the most fresh water from rivers.
- 18. The first rockets were launched in this century.
- 19. A tropical cyclone in the Atlantic Ocean.
- 20. The decade in which television become widely available around the world.
Down
- 1. Inventor of the diesel engine.
- 2. The first rockets were launched in this country.
- 3. The name aircraft body.
- 5. The vehicle invented about 3000 BCE.
- 6. The study of matter at rest.
- 10. The star closest to our sun.
- 13. The name for a jet-powered propeller engine.
- 14. The planet with the giant red spot.
- 16. The kind of energy contained in a rock on a cliff.
- 17. The first person to orbit earth.