Across
- 4. A circle that rolls upon the external or internal circumference of another circle.
- 5. distance above sea level
- 10. A measure of how far north or south an object is from the celestial equator
- 12. day From noontime to the next noontime; for Earth it is 24 hours.
- 14. Galilei Italian astronomer and mathematician who was the first to use a telescope to study the stars
- 15. A measure of how far north or south an object is from the celestial equator
- 16. Based on the belief that the sun is the center of the universe
- 19. (motion) The apparent motion of the planets when they appear to move backwards (westward) with respect to the stars from the direction that they move ordinarily.
- 20. path of the sun and the planets
Down
- 1. A model of the universe in which Earth is at the center of the revolving planets and stars.
- 2. The interval of time between successive geometric arrangements of a planet and an astronomical object, such as the Sun.
- 3. tilt The angle that a planet's axis is tilted from vertical
- 6. Brahe Influenced by Copernicus; Built observatory and collected data on the locations of stars and planets for over 20 years; His limited knowledge of mathematics prevented him from making much sense out of the data.
- 7. Each of the two times of the year when days and nights are of equal length
- 8. A slow motion of Earth's axis that traces out a cone over a period of 26,000 years
- 9. the highest point in the sky
- 11. point in a planet's orbit that is farthest from the sun
- 13. Ascension The angular distance eastward along the celestial equator from the vernal equinox to the intersection of the hour circle that passes through the body
- 17. Devised a model of the universe with the Sun at the center, and not earth.
- 18. Sphere imaginary sphere of which the observer is the center and on which all celestial objects are considered to lie.