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Determining Latitude 90°

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Presentation on theme: "Determining Latitude 90°"— Presentation transcript:

1 Determining Latitude 90°
90°  The position of the north star relative to the horizon depends on my latitude. At the north pole, it’s directly overhead (90 degrees from the horizon) Image:

2 Determining Latitude 40°
40°  The position of the north star relative to the horizon depends on my latitude. At the 45 degrees lat, it’s 45 degrees above horizon Image:

3 Determining Latitude 0°
The position of the north star relative to the horizon depends on my latitude. At the equator, it’s at horizon 0°  Image:

4 Determining Latitude 90° 40° 0°
90°  40°  0°  Image:

5 Determining Latitude When the North Star is at 90°
You must be at the North Pole (Latitude = 90°)

6 Determining Latitude When the North Star is at 45°
You must be at the halfway (Latitude = 45°)

7 Determining Latitude When the North Star is on the horizon
You must be at the equator (Latitude = 0°)

8 Determining Longitude
30° 20° 10° While there must be one and only one equator (90 degrees from each pole), where we put the prime meridian is inconsequential Image:

9 Determining Longitude
10° 20° 30° While there must be one and only one equator (90 degrees from each pole), where we put the prime meridian is inconsequential Image:

10 Determining Longitude
10° 20° 30° While there must be one and only one equator (90 degrees from each pole), where we put the prime meridian is inconsequential Image:

11 What is my Longitude? Boston, MA Greenwich, England Sun: noon
So if we choose zero as Greenwich, England, then TIME is the method of calculating how far we are away from the prime meridian. In NYC, 5 hours behind the time in Greenwich, we are at (5 hours) * (360 degrees / 24 hours) = 75 degrees West Boston, MA Greenwich, England Sun: noon Sun: noon Watch: 5:00 pm Watch: noon Image by Strebe

12 What must my current longitude be?
“Speed” of the Sun 360° 𝑑𝑎𝑦 = 15° ℎ𝑟 The sun is at the “noon” position, but my watch says it’s 5:00pm in Greenwich, England (0° longitude). What must my current longitude be?

13 What is my Longitude? 60° 30° 0° 75° 45° 15° Boston, MA 1 hr
So if we choose zero as Greenwich, England, then TIME is the method of calculating how far we are away from the prime meridian. In NYC, 5 hours behind the time in Greenwich, we are at (5 hours) * (360 degrees / 24 hours) = 75 degrees West Boston, MA 1 hr Greenwich, England Sun: noon Sun: noon Watch: 5:00 pm Watch: noon Image by Strebe

14 Try it out! What is your longitude if your Greenwich watch says 10:30am but the sun is at local noon? In what city is the Sun in the noon position when it is 4pm in Boston (longitude 75°)? 2 hours before = 22.5 degrees East of Greenwich = Sweden, Poland, Greece, Libya, Rwanda, South Africa 4pm Boston = 9pm Greenwich which means the sun has traveled 135 degrees from Greenwich noon. It’s now noon at 135 degrees West  Juneau, Alaska


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