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Columbia Astronomy
Earth, Moon, and Planets
| Question | Answer |
|---|---|
| North Celestial Pole (NCP) | Point on the celestial sphere defined by the projection of the earth's axis of rotation onto the sky due north. (axis of rotation projected onto celestial sphere due north) |
| South Celestial Pole (SCP) | Point on the celestial sphere defined by the projection of the earth's axis of rotation onto the sky due south (axis of rotation projected onto celestial sphere due south) |
| celestial equator | The great circle on the celestial sphere defined by the projection of the earth's equatorial plane onto the sky |
| zenith | Point directly overhead for any observer |
| meridian | arc of a great circle which intersects the horizon due north, passes through the zenith, and intersects the horizon due south |
| ecliptic | great circle on the celestial sphere defined by the projection of the earth's orbital plane onto the sky (also the path of the sun through the stars as seen by observers on earth) |
| Describe the rotation of the Earth | The earth rotates about an axis which is fixed in space. Sense of rotation given by right-hand rule. |
| Right-hand rule | Place the thumb of your right hand along the axis of rotation with your thumb pointing north. The fingers of your right hand curl in the direction of the earth's rotation |
| Describe North, South, East, and West as defined by planetary rotation. | North = direction of NCP South = direction of SCP East = direction of earth's rotation West = opposite direction of earth's rotation |
| "North and South are fixed directions in space, East and West are not." | North and South are fixed - defined by pointing along the earth's axis of rotation. East and west = in the direction of the earth's rotation and opposite to it. Two observers facing East on opposite sides of the earth, opposite in physical direction. |
| Apparent motion of the stars as seen from the North Pole. Where are the NCP, SCP, and Celestial Equator? Which stars are always above the horizon? Which are never? Which rise and set? | Observer @ north pole will see NCP@ zenith. SCP@ the nadir. Celestial equator on the horizon. Stars north of the c.e. (in the southern c.e.) are always below the horizon. No stars rise and set. Stars above horizon - counter-cl circles about the NCP |
| Apparent motion of the stars as seen from the South Pole. Where are the NCP, SCP, and Celestial Equator? Which stars are always above the horizon? Which are never? Which rise and set? | Observer on S.Pole sees SCP@zenith. NCP invisible (planet in the way)@nadir. C.E. on horizon. Stars in sch are always above horizon. Stars in nch are always below. No stars rise and set. Stars above horizon make clockwise circles around SCP |
| Apparent motion of the stars as seen from Kyoto, Japan (latitude 35 deg North). Where are the NCP, SCP, and Celestial Equator? Which stars are always above the horizon? Which are never? Which rise and set? | Observer in Kyoto will see NCP at elevation of 35deg above horizon due N. SCP@35 deg below horizon due S. C.e intersects horizon due E. crosses meridian at elevation 55 above horizon due S. intersects hroizon due w. |
| Apparent motion of the stars as seen from the equator. Where are the NCP, SCP, and Celestial Equator? Which stars are always above the horizon? Which are never? Which rise and set? | @equator sees NCP on horizon due N.& SCP on horizon due S. CE intersects horizon due E., crosses meridian at zenith, and intersects horizon due W. No stars are always above/below horizon. All stars rise/set. Stars c.wise around SCP, counter around NCP. |
| Apparent motion of the sun throughout the year from the North Pole | NCP directly overhead @zenith at north pole, stars make counter circles around it. Nch is always above the horizon, southern below. CE@horizon. 1/2 ecliptic N of CE is always above, 1/2 S is always below. No rise/set |
| Apparent motion of the sun throughout the year as seen from the Arctic Circle |
Created by:
queenofbabble
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