Finding Latitude
Using an Astrolabe
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Sunrise As the sun's rays first appear on the horizon, our sailor identifies the stars (the constellation) visible in the sky around the sun.
Noon: As the sun reaches its highest point in the sky during the day, our sailor takes out his astrolabe, holds it waist-high and looks down at the dial to see how many degrees the sun is above the horizon.
Afternoon Then he takes out the Rules for the Astrolabe and using the constellation in which the stars were located that morning (across the top of the table), and the number of degrees that the sun was above the horizon at midday, he looks up the latitude.
This astrolabe was made in 1605. Note the semi-circle on the bottom which is weighted so that the astrolabe remains steady even at sea.
