The Night Sky

1. The Night Sky

2. Constellations 88 official constellations

3. The Constellation Orion

4. The Constellation Ursa Major

5. The Celestial Sphere

6. North Celestial Pole Celestial Sphere North Pole Earth South Pole South Celestial Pole

7. North Celestial Pole Equator Celestial Equator South Celestial Pole

8. Earth’s Coordinate System Phoenix Lat = N33o 37’ 11” Lon=W111o 55’ 11’’

9. Celestial Coordinate System Declination Right Ascension

10. The Ecliptic The apparent path of the Sun across the Celestial Sphere during the Year. It intersects the Celestial equator at the Equinoxes at an angle of 23.5 degrees.

12. Autumnal Equinox – The Sun crosses the Celestial Equator heading South Vernal Equinox – The Sun crosses the Celestial Equator heading North

14. Summer Solstice- Sun furthest North of the Celestial Equator Winter Solstice- Sun furthest South of the Celestial Equator

16. 23.5 degrees

18. The Precession of the Earth’s Axis

19. 26,000 years

21. Timekeeping Mean Solar Day – Time from local noon to local noon averaged over the year 24 hours by definition Sidereal Day – Time for the Earth to rotate 360o on its axis 23 hours 56 min 4 sec

22. Timekeeping Tropical year – time from Vernal Equinox to next Vernal Equinox 365.2425 days Sidereal year – time for Earth to orbit the Sun exactly 360o 365.2564 days

23. 23.5 degrees

25. The calendar year is a Tropical Year Leap years every 4 years, but: Every Century, only have leap year if evenly divisible by 400 -> Years 1700, 1800, 1900, 2100, etc. not leap years -> Years 1600, 2000, 2400, etc. are leap years

26. The Motions of the Moon

27. What is a Month?

28. Sidereal Month- Time for Moon to revolve around the Earth. 27.3 Days Synodic Month- Time for a cycle of Moon’s Phases. 29.5 Days

29. The Phases of the Moon

31. Sidereal Month Completed New Moon New Moon

32. Eclipses

33. Solar Eclipse Penumbra Umbra

34. Lunar Eclipse