2. Observational Astronomy Mapping the Heavens

3. Coordinate Systems We have two different ways to locate objects in the sky: Celestial equatorial system -Right Ascension and Declination The horizon system -Altitude and Azimuth

4. Celestial equatorial system

6. Celestial Sphere

12. Observational Astronomy Locate your Star Charts

13. SFA Star Charts Star Chart 1 - Northern Region Star Chart 2 - Equatorial Region Star Chart 3 - Equatorial Region Star Chart 4 - Southern Region

15. SFA Star Chart 1 North Star “Big Dipper” “Little Dipper” “Pointer Stars” Right Ascension Declination

16. Chart 1 Problem Find the coordinates of Capella.

17. SFA Star Chart 1

19. How do you use these charts to view the night sky? Chart 1 – Face North – Find Meridian – Find the Field of View

20. SFA Star Chart 1 Today’s Date

21. North Horizon

22. Circumpolar Stars are stars that never set.

23. Charting the Sun’s Path Go to Charts 2 and 3

24. Celestial Equator Ecliptic Vernal Equinox Autumnal Equinox Summer Solstice Orion

25. Celestial Equator Ecliptic Vernal Equinox Autumnal Equinox Winter Solstice “Summer Triangle”

26. Chart 2 Problems (write in questions) Find the coordinates of Betelgeuse. Where is the Sun on March 15th? Where is the Sun on your Birthday?

27. How do you use these charts? Charts 2 & 3 – Face South – Find Meridian – Find the Field of View

28. Celestial Meridian for Today West HorizonEast Horizon Field of View

29. SFA Star Chart 4

30. The Horizon System Meridian Polaris Zenith Altitude Azimuth

32. Measuring Angles Altitude - the angle of a star above the horizon The North Star, Polaris, is not the brightest star in the sky but remains in a fixed position in the sky. The angle of Polaris above your horizon is the same as your latitude in degrees.

33. We can describe the angular position of an object in the sky by its altitude (a) above the horizon......and by its angular distance from the northmost point on our horizon, i.e. its azimuth (A)... north west north east north For example: a horizon A...both measured in degrees.

35. View from the Equator

36. View from the North Pole

37. Precession Precession is the slow wobble of the Earth’s axis due to the influence of the Moon. This means that Polaris will not be the North Star forever.......just for the rest of our lives. This is also why the Zodiac signs are no longer correct. e.g. Ophiuchus

38. Precession http://www.bing.com/images/search?q=precession&view=detail&id=249F77B3F23163F2B714DE90963BE9793 2FCF87D&adlt=strict http://www.bing.com/images/search?q=precession&view=detail&id=249F77B3F23163F2B714DE90963BE9793 2FCF87D&adlt=strict

39. Precession

40. Motions of the Sun and Stars Daily Motion –The rising and setting of the stars is caused by the Earth’s rotation about its axis. Annual Motion –The Earth’s orbit around the Sun causes different stars and constellations to be visible at different times during the year.

42. Constellations Constellations are recognizable patterns of stars in the sky. There are 88 constellations. (e.g. Orion) The 13 constellations along the ecliptic on your star chart are called the Zodiac Constellations.

44. The Constellation Orion

45. Asterisms Asterism are recognizable patterns of stars that is not one of the 88 constellations. For Example: The Big Dipper

46. Constellations Most bright stars have names -Mixed origin (Greek, Latin, Arabic) All stars in the constellations are identified related to their brightness -using Greek alphabet symbols - Usually α = brightest star, then β, then γ, etc.

47. Magnitude A stars apparent magnitude is also identified Lower number = Brighter star Higher number = Dim star

48. We can make a rough estimate of the angular separation of objects in the night sky by holding our hand out at arm’s length: A finger’s width is roughly 1 o, 1o1o

49. And a fist’s width is roughly 10 o 10 o