The position of stars in the sky changes ( the motion of the celestial sphere ) due to the rotation of the Earth. And the world revolving around the sun Humans have developed mathematical knowledge from sky observation. To create a clock and calendar to tell the time when observing the sky, we can calculate the position of the stars In the sky easily by means of a truce.
Changing positions because the world revolves around itself. The Earth revolves around 1 cycle for 24 hours and 24 hours. The position of the stars ( angles made to the sky ) changes 360 degrees for 1 hour. The position of the stars changes = 360/24 = 15 degrees. 1 minute the positions of the stars change = 15/60. = 0.25 degrees.
Example 1: Suppose today the sun rises at 6:00 am at 9:00 am the sun will rise from Horizon how many degrees. The sun rises in the east at6:00pm. To fall west at18:00am. It takes12 hours to charge an angleof 180 degrees , so the firsthour the sun moves= 180/12 = 15degrees , so at 9:00pm. The sun is. Height above the horizon = (9 – 6) x 15 = 45degrees.
Example 2: We see Orion overhead at 21:00 pm . That constellation
Orion will fall much time in one hour, the stars on the celestial equator, moving west at an angle = 180/12 = 15 degrees point. Overhead at an angle to the west horizon = 90 degrees. Therefore, the Orion will move to the west horizon. It takes = 90/15 = 6 hours. Therefore, the Orion will fall time = 21.00 + 6.00 (- 24.00) hours = 03.00 the following day.
Example 3: We can see the sun rising above the western horizon 4 times the diameter. How many minutes will the sun touch the horizon? Angular size of the sun diameter = 0.5 degrees. The sun moves 4 times the diameter = 4 x 0.5 = 2 degrees. 1 hour. The sun moves = 180/12 = 15 degrees. The sun moves 1 degree, takes = 60/15 = 4. Minutes, therefore it takes = 2 x 4 = 8 minutes before the sun touches the horizon.