1. Astronomy Vocabulary
Mr. Ahearn
2013

2. Altitude
The angular elevation of an object above the horizon

3. Antarctic Circle
66.5 degrees south Sun doesn’t rise on the winter solstice of the southern hemisphere Doesn’t set in the northern hemisphere

4. Arctic Circle
66.5 degrees north Sun doesn’t rise on the winter solstice in the northern hemisphere Doesn’t set in the southern hemisphere

5. Celestial Object
Objects in sky beyond Earth’s atmosphere

6. Equinox
A day that the sun rises due east and sets due west. Day and night are equal lengths. Vertical Rays at the equator.

7. Geocentric
A model of the universe with the the center

8. Heliocentric
A model of the solar system with the sun at the center.

9. Revolution
Movement of one object around another.

10. Rotation
Spin around an axis (itself)

11. Solar Noon
The which the Sun reaches its highest point in the sky.

12. Solar Time
Time based on observations of when the sun reaches its highest point and crosses a north-south line through the sky.

13. Summer Solstice
June 21st northern hemisphere Dec 21st southern hemisphere Longest insolation Vertical Tropic of Cancer

14. Tropic of Cancer
23.5 degrees north Greatest latitude north of the equator reached by sun’s vertical rays.

15. Tropic of Capricorn
23.5 degrees south Greatest latitude south of equator reached by Sun’s vertical rays.

16. Vertical Ray
Sunlight that strikes Earth’s angle of 90 degrees

17. Winter Solstice
Dec 21 northern hemisphere June 21 southern hemisphere Shortest day of the year

18. Zenith
Point in sky directly over observers head.