kkl asked in 科學天文與太空 · 1 decade ago

# altitude and azimuth

1.What is a north-south line?

2.Starting from the N-S Line, the position of an object in the sky can be described by measuring its ______ and ______.

3.What do altitude measurements show?

4.What do we call the N-S Line that passes directly overhead, through the zenith?

5.An object located at 90° altitude would be located at the __________

6.Azimuth readings go from 0° to 270°. Altitude readings go from 0° to ____

7.The instrument used to measure altitude is the _______.

The instrument used to measure azimuth is the _________.

8.Why are two measurements needed to determine the location of object in the sky?

9.What effect does observation position have in measurements of azimuth and altitude?

10.Why is azimuth measured from 0 ° to 360 °, while altitude is only measured from 0 ° to 90 °?

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• 1 decade ago

relevant reference book is not available now. only can try to ans as follows. :

1. north-south line on sky is called as ??. reverting. (on earth, it called as Meridian line.)

2. azimuth and altitude

3. altitude is the angle measured from horizontal to the star vertically. 90 degree deduct altitude, the result shows the arc between the observation position and the star&amp;#039;s geographic position. eg, if you located at at 80degree north latitude, you can find altitude of polar star is 80 degree high. then, your position is 10 dgree (=600 minutesx1852meter=1,111,200meters) of earth arc far upto to north pole.

4. on sky, it called aslocal ??? i forget. reverting. (on earth, local meridian)

5. geographic position

6. 90 degrees

7. sextant and ???tor (I forget)

8. the object is in space of three dimension. thus, we need two factors to locate its position.

9. more closer to the star geographic position, the star&amp;rsquo;s altitude will be more bigger.

More northward of observation position, the azimuth will be more bigger once the star is at east side of the observer. If the star is at west side of the observer, the azimuth will then become more lesser instead.

10. Once altitude is bigger than 90, the observer should turn to another direction (to turn 180 degrees) to measure its altitude instead. Thus, altitude is only measured upto 90.

2009-02-09 21:34:46 補充：

8. we only need to know a line being pointed to the star. for which, we need to have two measurements ie azimuth and altitude for describing such pointer. we do not need to know star's distance from earth. thus, 3 factors which are required in a 3 dimension space are not required.

reverting others

2009-02-13 10:53:43 補充：

1. north-south line is a line connecting north and south pole. It is called as celestial meridian. A celestial meridian for a particular star is called as hour circle.

2. azimuth and altitude

2009-02-13 10:55:13 補充：

3. altitude is the angle measured from horizontal line to the star vertically. 90 degree deduct altitude is called as co-altitude. The result shows the arc between the observation position and the star`s geographic position. eg, if you located at 80 degree north latitude, you can find

2009-02-13 10:56:00 補充：

altitude of polar star is 80 degree high. Then, your position is 10 degree (=600 minutesx1852meter=1,111,200meters) of earth arc far upto to north pole, ie 1.111Km far.

4. local celestial meridian (or local hour circle).

5. observer’s position.

2009-02-13 10:57:02 補充：

6. (azimuth readings should go from 0 to 360 but not 270). altitude goes from 0 to 90 degrees

7. to measure altitude uses sextant and to measure azimuth uses azimuth circle

8. we image all stars in the heaven has same distance to the earth. Namely, we consider all stars

2009-02-13 10:58:21 補充：

are located at the surface of a sphere which is called as celestial sphere. To locate a star, we only need to define a line being pointed to the star. for which, two measurements ie azimuth and altitude for describing such pointer are good enough. We do not need to know star's distance from earth.

2009-02-13 10:59:40 補充：

Such coordination system can meet our requirements for finding our position on earth. As celestial sphere is a two dimension coordination system, we thue only need two measurements to determine the location in the sky. It similar to the standard X & Y axis two dimension system.

2009-02-13 11:00:43 補充：

9. more closer to the star`s geographic position, the star will appear with more higher altitude. More northward of observation position, the star will appear at more southward direction. Namely, the azimuth of the star at east side will be more larger and for

2009-02-13 11:01:32 補充：

west side star the azimuth will become lesser.

10. Once altitude is bigger than 90, the observer should turn backward (to turn 180 degrees) to measure its altitude instead. Thus, altitude is only measured upto 90. for instance, a star with altitude of 96 degrees, its

2009-02-13 11:03:47 補充：

correct altitude should be 84 degrees. Such system is more significant and can simplify relevant calculations.

believe 99% of abv is correct.

補充框太小很累

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