Across
- 2. large lens or mirrow on a telescope
- 4. a space that does not contain any matter
- 5. first artificial object to orbit the earth.
- 6. group of star called the "seven sisters"
- 8. explosion of a star
- 10. forms the bright flash of lightning bolt
- 13. most basic unit of time
- 15. an abrupt discharge of electricity through the air
Down
- 1. faster rotation of any planet
- 3. measures the distance from the ground to the base of clouds
- 7. metallic object that is smaller than the planets
- 9. measure the distances to stars
- 11. a narrow funnel of whirling wind produced by a thunderstorm
- 12. heart of the comet
- 14. notable star of Cygnus