Bifilar Sundial Applet
Enter latitude in decimal degrees (northern positive, southern negative),
enter longitude in decimal degrees (eastern positive, western negative),
then press "Apply input".
you may use the keys "h", "d", "m" to
increase the hour, date, or month,
|Click into the grid
plane to change the gnomon position.
This sundial has two non-intersecting threads parallel to the horizontal dial plane. The upper thread (distance a above the plane) is oriented North-South, the lower (distance b) is orthogonal to the first. The intersection of the two threads' shadows gives the time.
The lines of hour angles are equidistant if b = a sin(latitude) and intersecting at P with PQ = a sin(latitude).
How to get this applet for offline use
More of my sundials:
The grid size is b=a cos(latitude).
Click into the grid to change the position of the gnomon.
Choose "Current" from the "Analemma..." menu to show the current position of the sun, the analemma for the current time and the diurnal line for the current day:
An analemma is the figure-of-eight shape that results if the Sun's position in the sky is recorded at the same time of day throughout the year. As a consequence the gnomon draws a similar figure. Watch an animation.
More of my sundial applets ...
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Please visit my GeoAstro Applet Collection
Last Modified: 2013, Jul 28
© 2010-2013 Juergen Giesen