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• What would you do without all these things?
• Step 1 – figure out what hemisphere you’re inPlenty of ocean to get lost in
• Celestial pole – lucky if you’re in the north, polaris is at the poleLearn your landmarks – the two bears in the north, the southern cross in the southFind the southern pole by drawing a line from acrux and the tip of the cross and between agena and rigelcentaurus, lines intersect at the southern celestial pole
• 20 billionths of an inch4 billion miles

1. 1. Sailing by Starlight: the Lost Art of Celestial Navigation<br />Andrew Thaler<br />
2. 2. Do you know where you are?<br />
3. 3. Finding your way home<br />
4. 4. Finding your way home<br />Southern Sky<br />Northern Sky<br />
5. 5. Finding your way home<br />How do you travel in a straight line?<br />Latitude hook<br />Must be calibrated to a specific location<br />Polaris above the loop, head south<br />Polaris below the loop, head north<br />Kamal<br />Why does this work?<br />
6. 6. Determining Latitude<br />Polaris<br />tan θ = x/y<br />θ = Latitude<br />X<br />θ<br />Horizon<br />y<br />
7. 7. Determining Latitude<br />Accurate to within 1 Degree<br />1 degree of latitude = 60 minutes<br />1 minute = 1 nautical mile<br />Polaris is 430 light years away<br />2.5 X 1015 miles<br />If surveyors were as accurate as Polaris - 0.0000000002 inches<br />If Polaris was as accurate as a surveyors - 4,000,000,000 miles<br />
8. 8. Latitude is θ<br />Cross staff<br />Quadrant<br />Astrolabe<br />Octant<br />Sextant<br />
9. 9. Longitude<br />The X-Prize of the millennium<br />No accurate method until 19th<br />century<br />3 puzzle pieces<br />Rotation of the earth = 15o per hour<br />Time the sun peaks at prime meridian = 1200<br />Time (GMT) the sun peaks at your location<br />
10. 10. Relative Longitude<br />Not very accurate!<br />Find a star near the eastern or western horizon<br />Measure the altitude of that star at the same time every night<br />Changes in degrees correspond to movement east or west<br />2 Caveats<br />Need to correct for latitude<br />Need to know what time it is<br />
11. 11. What time is it?<br />The sky is a clock, too<br />Mariner’s Nocturnal<br />Measures the angle between Polaris and Ursa Major or Ursa Minor<br />
12. 12. Using the Nocturnal<br /><ul><li>An analog computer
13. 13. Set the dial to the date
14. 14. Sight Polaris through the center hole
15. 15. Rotate the arm until it lines up with the head of Ursa Major</li></li></ul><li>Astronomers and Mariners<br />None of these tools were invented for navigating<br />We know where we are on earth because we wanted to know where we are in the universe<br />
16. 16. Questions?<br />
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