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Sunrise and Sunset Finding the latitude by a watch Select "Rise" or "Set" from the Details menu. Click the applet area first. Then: enter decimal degree values for Latitude (southern negative) into the text field of the applet, and press Enter key, enter decimal degree values for Longitude (western negative) into the text field of the applet, and press Enter key. Latitude 51.51, Longitude 13.41 is Berlin/Germany. You may use the keys y, m, d, h to increase the year, minute, day, or hour, or shift key and y, m, d, h to decrease the year, minute, day, or hour. To increase or decrease the seconds use the butons or the keys s or shift key and s. The time difference fon rise or set is indicated by Δt=... Select "Rise" or "Set" from the Details menu to reset to Δt=0 s. Select from the "Details" menu to get a data table or diagrams. Repeat "Zoom in" or "Zoom out". The applet is computing and drawing sunrise and sunset. You can simulate the method decribed below. Measuring the duration Δt of the Sun's diameter rising or setting the approximate latitude φ can be computed by the following formula (diameter D of the Sun in arc minutes, Δt in seconds, declination δ) Select "Time Table" from the Details menu: Select "Time Table/Graph" from the Details menu (please be patient, the calculations will take about half a minute): Another simple method to determine the latitude.

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N. Liapin: A method of finding the approximate latitude by observing the Sun's diameter at rising or setting

© 2011 J. Giesen

Last modified: 2011 May 9