The Celestial Sphere

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The Celestial Sphere
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The Celestial Sphere

• Appears as a dome over our heads.

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The Celestial Sphere

• Appears as a dome over our heads.
• Stars seem embedded like tiny jewels

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The Celestial Sphere

• Appears as a dome over our heads.
• Stars seem embedded like tiny jewels
• Stars all appear to be the same distance from
  Earth.
• Makes a great model of what we see.

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Model of the Celestial Sphere
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Notice that the Celestial Poles are directly
above the Earths Poles...
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C.N.P.
Notice that the Celestial Poles are directly
above the Earths Poles...
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C.N.P.
Notice that the Celestial Poles are directly
above the Earths Poles...
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C.N.P.
Notice that the Celestial Poles are directly
above the Earths Poles...
C.S.P.
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C.N.P.
Notice that the Celestial Poles are directly
above the Earths Poles...
C.S.P.
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C.N.P.
C.S.P.
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and that the Celestial Equator is directly above
the Earths Equator.
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and that the Celestial Equator is directly above
the Earths Equator.
Celestial Equator
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and that the Celestial Equator is directly above
the Earths Equator.
Celestial Equator
Celestial Equator
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Declination
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Declination is like latitude.
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
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90o (dec)
Declination is like latitude.
Declination uses () and (-) to denote
positions north and south of the Celestial
Equator.
0o (dec)
- 90o (dec)
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Right Ascension
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Right Ascension is like longitude.
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Right Ascension is like longitude.
Positions are measured in hours and minutes in
one direction only
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• By convention, the great circle with right
  ascension of 0 hours runs through a point in the
  constellation Pisces at which the ecliptic
  crosses the celestial equator, and right
  ascension increases going eastward

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6h
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6h
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6h
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6h
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6h
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6h
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12h
6h
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12h
6h
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12h
6h
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12h
6h
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12h
6h
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12h
6h
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18h
12h
6h
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18h
12h
6h
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18h
12h
6h
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18h
12h
6h
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18h
12h
6h
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18h
12h
6h
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18h
0h
12h
6h
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Using both Declination and Right Ascension
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Using both Declination and Right Ascension
any star can be located on the Celestial Sphere.
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For Example
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For Example
A star like Rigel
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For Example
A star like Rigel is found at
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For Example
A star like Rigel is found at
- 8o 11 (dec)
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For Example
A star like Rigel is found at
- 8o 11 (dec)
5 h 15 (RA)
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For Example
A star like Rigel is found at
- 8o 11 (dec)
5 h 15 (RA)
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For Example
A star like Rigel is found at
- 8o 11 (dec)
5 h 15 (RA)
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For Example
A star like Rigel is found at
- 8o 11 (dec)
5 h 15 (RA)
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For Example
A star like Rigel is found at
- 8o 11 (dec)
5 h 15 (RA)
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Good To Know

• The right ascension and declination of each star
  are fixed from day to day and year to year.  But
  because the Earth is wobbling in space because of
  the gravitational influence of the Moon and Sun,
  the coordinates of celestial objects change over
  the course of decades.  Every 50 years or so,
  star maps and star coordinates are updated. 
  Current star maps are accurate as of the year
  2000.