Astronomy 1.1

2. to spin about an axis, for example the Earth spins about its polar axis in one day.
5. the intersection of the imaginary plane which contains the trajectory of Earth’s orbit around the Sun and the celestial sphere.
9. the visible star to which Earth’s north polar axis nearly points; sometimes called the north star.
11. the amount of time it takes for the Earth to make one complete rotation relative to the stars: 23 hours, 56 minute, 4 seconds.
14. one of the 88 regions that comprise the celestial sphere – each region contains a pattern of stars that seems to form a mythological creature or object.
15. a pattern of stars that – with imagination – seems to resemble something.
16. the component of the astronomical coordinate system that measures how many degrees north (positive) or south (negative) of the celestial equator an object is.

1. an imaginary sphere centered on the earth onto which astronomers model stars as being points of light.
3. the direction defined to be directly above an observer.
4. the amount of time from one sunrise to the next: 24 hours (average).
6. the component of the astronomical coordinate system that measures how many hours east of the spring equinox direction an object is.
7. to move around another object, for example the Earth moves around the Sun in one year.
8. the 13 constellations (12 astrological ones, plus Ophiuchus) which lie in the plane of Earth’s orbit (i.e. the ecliptic) and through which the Sun appears to move throughout a year.
10. the intersection of the Earth’s equatorial plane with the celestial sphere.
12. the slow wobble of the Earth’s axis of rotation in a clockwise direction that completes one cycle every 26,000 years.
13. a no-cost, web-based simulation of what astronomers might see from the surface of the Earth.