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22 Cards in this Set
- Front
- Back
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Polaris
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The North star
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Circumpolar
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Notice that stars closer to the NCP are above the horizon longer than those farther away from the NCP. Those stars within an angular distance from the NCP equal to the observer's latitude are above the horizon for 24 hours---they are circumpolar stars. Also, those stars close enough to the SCP (within a distance = observer's latitude) will never rise above the horizon. They are also called circumpolar stars
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celestial sphere
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great, hollow, sphere surrounding the Earth. The stars are attached to this sphere---some bigger and brighter than others---which rotates around the stationary Earth roughly every 24 hours
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celestial sphere appears to move (direction)
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westward
(stars appear to rise in the east and set in the west) |
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celestial sphere model allows us to:
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predict motions and locations of stars and planets relative to a location on Earth
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angles on the sky
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Used to measure distances on the imaginary celestial sphere
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Each degree is divided into
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60 minutes of an arc
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The Sun and Moon are both about ___ degrees
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The Sun and Moon are both about 0.5 degrees = 30 arc minutes in diameter.
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The arc from the north point on the horizon to the point directly overhead to the south point on the horizon is _____.
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The arc from the north point on the horizon to the point directly overhead to the south point on the horizon is 180 degrees.
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any object directly overhead is _________above the horizon
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any object directly overhead is 90 degrees above the horizon
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any object ``half-way up'' in the sky is about __________ above the horizon.
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any object ``half-way up'' in the sky is about 45 degrees above the horizon.
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how many degrees is 30 arc minutes
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0.5 degrees
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how many degrees is 10 arc seconds?
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0.00278
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How many Moon diameters would it take to span the distance from a point on the eastern horizon to a point directly opposite on the western horizon?
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6 moon diameters
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North and South Celestial Poles
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These are the points in the sky directly above the geographic north and south pole, respectively. The Earth's axis of rotation intersects the celestial sphere at the celestial poles.
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The number of degrees the celestial pole is above the horizon is equal to the ________of the observer
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The number of degrees the celestial pole is above the horizon is equal to the latitude of the observer
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celestial equator is always ________
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90 degrees from the poles
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All the stars rotate in a path that is ______________________
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All the stars rotate in a path that is parallel to the celestial equator
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zenith
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point straight overhead on the celestial sphere for any observer
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zenith is always ___ degrees from the horizon
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90 degrees
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meridian
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arc that goes through the north point on the horizon, zenith, and south point on the horizon
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zenith and meridian change with respect to
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the stars and one's location on earth
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