Instructions: Read the link Geographic Projections. Then read appendix 3 on your
ID: 106658 • Letter: I
Question
Instructions: Read the link Geographic Projections. Then read appendix 3 on your text book. Now you are ready to complete this homework. Total (20 points) Hey guys Appendix III in your book is great it has all the info and the best graphics I have seen on this topic. Still more on this! Local noon is the time when Sun reaches its maximum elevation on a given longitude. E.g Prime meridian England happens at 12:00 GMT So 360 degrees divided by 24 = 15 degrees per 1 hour of change on local noon. Local noon at Miami is 17:00 GMT. So the longitude of Miami is 80.00 West. Five hours and few minutes difference. But if you set your clock at 12:00 Miami local noon! Then you sail away and find that next local noon is at 11:00 then (in this case) you have sailed 15 degrees East of Miami so your longitude is 65 degrees west! Polaris the North Star and the Southern Cross can be used to calculate Latitude. Their elevation on degrees above the horizon = your Latitude. So if Polaris is 45 degrees above the horizon your Latitude is 45 degrees North! You do not need a Sextant!
5. You use an instrument called a sextant and find the following angles of the North Star or Southern Cross above the horizon. At what latitude are you for each? (Don’t forget to mention N or S) (5 pts)
Observation
Your latitude
North Star (Polaris) is 5 degrees above horizon
Southern Cross is 23 degrees above horizon
Southern Cross is 89 degrees above horizon
North Star is directly above you
North Star is located on the horizon
6.Using an accurate clock and setting your watch for local noon at your home port, determine your longitude given the following information: Note: Miami Longitude is 80°W, San Diego Longitude is 110°W. (Don’t forget to mention E or W) (3 pts)
Observation
Your longitude
You leave Miami and local noon shows 11am
You leave Miami and local noon shows 8am
You leave San Diego and local noon shows 2pm
You leave San Diego and local noon shows 5pm
Observation
Your latitude
North Star (Polaris) is 5 degrees above horizon
Southern Cross is 23 degrees above horizon
Southern Cross is 89 degrees above horizon
North Star is directly above you
North Star is located on the horizon
Equator 60, 60 180 160 140 120 100 80 60 20% 80° 100 120 140 160 180Explanation / Answer
5. Since it's given :
Polaris the North Star and the Southern Cross can be used to calculate Latitude. Their elevation on degrees above the horizon = your Latitude. So if Polaris is 45 degrees above the horizon your Latitude is 45 degrees North!
Note : The Southern Cross is not exactly aligned with the celestial South Pole,and is mainly used to point towards South.However, for convenience the old mariners used it to calculate latitude in the Southern Hemisphere.
6. Since it is given that 15 degrees change in longitude is involved for change per hour in local noon timing.Note that moving towards East the local noon time is achieved first than your home town and moving Westwards the local noon is achieved later than your home town.This is because sun rises from East and moves towards West.So Easterly places show Noon before and Westerly places show Noon after your local noon timings.
observation Latitude North Star (Polaris) is 5 degrees above horizon 5 Degrees North Southern Cross is 23 degrees above horizon 23 Degrees South Southern Cross is 89 degrees above horizon 89 Degrees South North Star is directly above you North Pole( 90 Degree North) North Star is located on the horizon Equator ( 0 Degrees )