Download Contrast the old definition of constellation with the

❑ 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.
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Constellations for astronomers
A specific, delineated
region of the sky, stars
and objects placed within
official borders set in
1928.
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❑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?
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❑ 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
A
B
C
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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:
RA: 00hr 10min 05sec and Dec: +29o 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:
RA: 00hr 10min 05sec and Dec: +29o 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
❑ 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
❑ 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.
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❑ 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.
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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?
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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?