Constellations pg. 617-620

1. Constellations pg. 617-620 1. # of stars? 2. Maps of sky Declination Right Ascension Earth’s spin 3. Constellations Define Names of key ones Asterisms

2. There are about 6000 named, visible stars in the sky.

3. Astronomy: the oldest science! Aristotelian view Has the earth and sky on fixed spheres • The ancients imagined that the Earth was surrounded by a canopy of stars

4. The Celestial Sphere:a globe of the sky! An imaginary bubble that surrounds Earth onto which all the stars are positioned. Like Earth, the Celestial sphere has a “North Pole”, a “South Pole”, and an equator.

5. To locate a place on the surface of the earth we use coordinates.What is the location of Chicago? Shuffle the deck and have sum fun

6. Stars, constellations, planets, can be found using the coordinates of declination and right ascension on the celestial sphere. Locate Cygnus the Swan (looks like a cross)

7. DEC (declination) DEC is measured from the celestial equator in degrees (similar to __________). Measurement to the NORTH is positive. The celestial North Pole is at +90 degrees DEC. Measurement to the South is negative. The South Celestial Pole is at _______degrees DEC

8. RA(right ascension) is similar to _______ is measured in hours, minutes, and seconds, as if we were measuring time instead of position! 0-24 hrs RA reads to the EAST. Astronomers decided to begin RA at the point where the path of the ecliptic crosses the celestial equator: the first day of SPRING. (vernal equinox)

9. We see a “flat” image of the stars in the constellations, but the stars are actually located at varying distances from earth.

10. Is the Celestial Sphere tipped over?

11. Is the Celestial sphere tipped over? It is actually Earth that is at an angle (tipped over at an angle of 23.5° Ecliptic: the path of the sunthrough the sky

12. Circumpolar Constellations

13. Why did the North Star Change? Precession • The Earth is not a perfect circle so it does not have a perfect rotational spin. It “wobbles” like a top. • So, Polaris has not always been the “North” Star.

14. Has Polaris always been our North Star?

15. Celestial Portraits • Human brains naturally create patterns. • What do you see when you look at the clouds? • The ancients did the same when they looked up at the sky.

16. Constellations • A name given to a group of stars • 88 in all • What do you notice about the constellations that follow? http://www.videojug.com/film/what-is-a-constellation http://www.youtube.com/watch?v=QXeEAQtC75g

17. Zodiac Constellations The 12 constellations that move through during the year.

18. Do you see a pattern in these stars?

19. Cassiopeia

20. Corona Borealis The Northern Crown

21. Draco the Dragon

22. Ursa Minor: Little Dipper The last star in the handle of the Little Dipper is the North Star: Polaris: The North Star http://www.youtube.com/watch?v=N93WV61ETo8

23. The Big Bear Can you find the stars of the Big Dipper in the constellation?

24. Asterisms • A named group of stars that are part of a larger constellation • Example • The Big Dipper is part of the larger constellation Ursa Major

25. The “tea pot” asterism in the constellation Sagittarius

26. You probably noticed Constellations Tell a story • Orion was a mythical hero and hunter, and in his amorous pursuit of the Pleiades (the 7 daughters of the giant Atlas), the Gods placed them in the sky. And Orion chases after them in the sky for all eternity.

27. Your Turn! • Look for a pattern, picture, figure, of an object, person, by connecting the stars. • Outline the figure. • Name the constellation • Create a mythological story to go with your constellation

28. Constellations pg. 714 • 88 constellations in all • We still use 48 of the ancient ones and have added 40 new ones • 28 are in the northern sky, 48 are in the southern, • 12 are the zodiac constellations • In the Northern Hemisphere their named for mythology • In the Southern Hemisphere they have modern names