Please use complete sentences in your response and clearly indicate which part o
ID: 110755 • Letter: P
Question
Please use complete sentences in your response and clearly indicate which part of the question you are answering.
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(a) Describe two different ways to figure out your latitude by observing the sky. Your description needs to include what you would observe and also how that "observable" quantity is related to the latitude.
(b) Describe how having an accurate watch should allow you to figure out your longitude with one observation of the sky. Include what you observe and how that is related to the longitude.
Explanation / Answer
(a) If it is night, the process of finding latitude is quite easy, what we have to do is to find the North Star (Polaris). It situated directly to the north along the line of the axis of the Earth. Thus if we are in north pole the North Star will be over our head (thus making an angle of 900 with the horizon) and for the equator, North Star will be on the horizon.
So, If we can find the location of the north star at the sky and determine its angle with the horizon, the angle will be our latitude.
Things really get complicated at the day-time. The only visible object in the sky on day time is the Sun. To know the longitude firstly we have to find the angle that the Sun is making below the vertical at 12 noon (local time). This angle will serve as the latitude only on the March 21st (spring equinox) and September 21st (autumn equinox). For winter solstice (December 21st), one needs to subtract 23.45 degrees from the angle measured because the Earth is tilted towards the Sun, moving the Sun's position in the sky. And, at the summer solstice (June 21st), one needs to add 23.45 degrees. In between necessary adjustment is needed keeping in mind that the variation happens from March 21st to June 21st for 00 to 23.450 and from that, it again changes to 00 at September 21st and from that to 23.450 at December 21st. The simple unitary method will do.