Seasons & Atmosphere

2. The lowest layer of Earth's atmosphere
4. The season experienced when the earth's axis is tilted toward the sun.
5. The season experienced when the earth's axis is tilted away from the sun.
6. One celestial object moving around another
8. This occurs in December and marks the beginning of winter in the Northern Hemisphere.
14. This occurs in June and marks the beginning of the summer in the Northern Hemisphere.
17. Outermost layer extending into space.
19. The result of the tilt of Earth's axis and the yearly revolution around the sun.
20. Protective layer in the atmosphere that shields the Earth from UV radiation.
21. Leaning toward or away from another object.
22. An imaginary line that passes through Earth's center and North & South poles.
23. Energy emitted from the Sun that can cause skin cancer.

1. Half of a sphere
2. Largest layer that reaches highest temperatures.
3. The season between winter and summer.
7. The spinning of an object on a fixed point, causing day & night cycles.
9. This occurs in March and marks the beginning of spring in North America.
10. Two time of the year when day or night lengths are at their longest or shortest.
11. 2nd layer of the atmosphere that contains ozone.
12. The season between summer and winter.
13. This occurs in September and marks the beginning of fall in North America.
15. Layer where meteoroids burn up.
16. Two times a year when the day and night lengths are about 12 hours each.
18. Imaginary line drawn around the earth equally distant from both poles.