Motion of the Sun II

thingiverse

Here is a version of thing:2069650 that allows one to estimate the hours of daylight during the solstices. Models are provided for cities at Northern Latitudes of 0, 33, 42, and 51 degrees as well as a model for Rio de Janeiro at 23 degrees South Latitude. The idea for the models comes from the geomancy web site - http://www.geomancy.org/index.php/astronomy/orthographic-projections OpenSCAD code is included. A second openSCAD program calculates projections of the 3D models onto the xy plane. DXF files are included. PNG images were also calculated and converted to a PDF file, also included. The pdf images, although distorted by projection, can be used to determine azimuths, altitudes, and daylight hours. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator (5th Generation) Rafts: Yes Supports: No Resolution: 0.3 mm Instructions For North Latitude Models The models show the yearly movement of the sun in the sky. The hemisphere represents the sky, consider yourself to be looking upwards from the center of the circle that forms the base. The arc from due east to due west represents the movement of the sun through the sky on March 21st and September 21st, the equinoxes. The arc to the north of the equinox represents the movement of the sun on June 21st, the summer solstice, and the arc to the south of the equinox represents the movement of the sun on December 21st, the winter solstice. During the year the sun takes paths between the solstices. If the viewer is at the equator the arcs for the summer and winter solstices are of equal length as are the hours of daylight and night. The model is marked at the base at intervals of 10 degrees. These can be used to find azimuths for the solstice sunrises and sunsets. Start at due north and count towards the east. The arc from due north to due south is also marked at 10 degree intervals. It can be used to determine the altitude of the sun at the solstices. Start at due south and count towards the north. The solstice arcs are marked at intervals of 15 degrees (1 hour) and the marks can be used to estimate the hours of daylight. Count the number of intervals in the whole arc. See the geomancy web site for more information.