Contrast the Old Definition of Constellation with the Astronomers' Definition of Constellation State Why We See Differe

❑ Contrast the old definition of constellation with the astronomers’ definition of constellation

❑State why we see different constellations during different times of the year.

❑ Summarize what is meant by the “Celestial

Sphere” and why the concept is useful.

❑ Interpret those motions-of-the-celestial-sphere crazy images. 1 Constellations for astronomers

A specific, delineated region of the sky, stars and objects placed within official borders set in 1928.

2 ❑Contrast the old definition of constellation with the astronomers’ definition of constellation We see different constellations throughout the year. We can see Pegasus now, but not Orion. In January, we’ll be able to see Orion, but not Scorpio. Why? What is happening? What is involved?

3 ❑ State why we see different constellations during different times of the year. !Motions in the Sky The Reason for Seasonal Constellations

4 ❑ State why we see different constellations during different times of the year. The Celestial Sphere

5 Summarize what is meant by the “Celestial Sphere” and why the concept is useful. Practice with celestial coordinates

6 Altair Andromeda Galaxy Messier 31

Enif

21 h You decided to purchase a registered star, on sale, for $80 (hey, it came with a certificate!). The coordinates are:

hr min sec o RA: 00 10 05 and Dec: +29 55’ 53” 7 Altair Andromeda Galaxy Messier 31

Enif

21 h You decided to purchase a registered star, on sale, for $80 (hey, it came with a certificate!). The coordinates are:

hr min sec o RA: 00 10 05 and Dec: +29 55’ 53” 7 ❑ Contrast the old definition of constellation with the astronomers’ definition of constellation OLD: An animal, mythological person or creature, thing representing cultural significance, etc.

8 ❑ Contrast the old definition of constellation with the astronomers’ definition of constellation OLD: An animal, mythological person or creature, thing representing cultural significance, etc. NEW: A specific, delineated region of the sky, stars and objects placed within official borders set in 1928.

8 ❑State why we see different constellations during different times of the year.

9 ❑State why we see different constellations during different times of the year. As the Earth orbits (revolves around) the Sun during the year, the Sun appears to move from west to east against the celestial sphere and its constellations. If the Sun is out, then its light prevents us from seeing other stars.

9 ❑ Summarize what is meant by the “Celestial Sphere” and why the concept is useful.

The celestial sphere is a model of the sky, the dome containing the Sun, Moon, stars, planets, Milky Way Galaxy, all things celestial.

As with all models, it provides a means of understanding and describing objects, events, and features.

The elevation of the Sun varies at different times of the year in Boulder. Polaris is always 40° above the northern horizon in Boulder (same as Boulder's latitude). The celestial equator is also always fixed at 50° above the southern horizon. During the course of the year, the Sun will move 23.5° to the north of and to the south of the celestial equator. It will be furthest north during the summer solstice; it will be furthest south during the winter solstice. Rewrite the above paragraph, applying it to Seattle. Use 48 deg. N latitude to make the calculations a bit easier.

6. Where will the north celestial pole be located if you traveled to the North Pole?

14 6. What if you traveled to the equator? If all stars are circumpolar if you lived at the north pole, and all stars rise and set if you lived on the equator, what can you state about the motion of stars if you lived in between the north pole and the equator? 5. How does the motion of the star that is the same number of degrees above the celestial equator as your latitude differ from that of a star on the southern horizon?