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If your latitude is north of the equator you will subtract the declination angle from your latitude angle. If the value is negative that is how many degrees up from the marked north line your altitude will be. If your value is positive, that is how many degrees up from the marked south line your altitude will be.
If your latitude is north of the equator you will subtract the declination angle from your latitude angle. If the value is negative that is how many degrees up from the marked north line your altitude will be. If your value is positive, that is how many degrees up from the marked south line your altitude will be.


Equation for 18 degrees north
 
 
<b>Equation for 18 degrees north </b>


June 15th
June 15th


<math> 18° - (+23°26') = -5°26' </math>
18° - (+23°26') = -5°26'
Solar noon will five degrees
Solar noon will be 5°26' towards the north from perpendicular from the center of your circle.
 
 
December 15th
December 15th
18° - (-23°26') = 41°26'
Solar noon will be 41°26' towards the south from perpendicular from the center of your circle.


If your latitude is south of the equator you will add the declination angle to your latitude angle. If the value is negative that is how many degrees up from the marked south line your altitude will be. If your value is positive, that is how many degrees up from the marked north line your altitude will be,
If your latitude is south of the equator you will add the declination angle to your latitude angle. If the value is negative that is how many degrees up from the marked south line your altitude will be. If your value is positive, that is how many degrees up from the marked north line your altitude will be,


Equation for 18 degrees south,
<b>Equation for 18 degrees south</b>
 
June 15th
June 15th
December 15th


For the angle for sunrise and sunset you can use this site : http://www.sunearthtools.com/dp/tools/pos_sun.php
18° + (+23°26') = 41°26'
Solar noon will be 41°26' towards the north from perpendicular from the center of your circle.
 
 
December 15th
18° + (-23°26') = -5°26'
Solar noon will be 5°26' towards the south from perpendicular from the center of your circle.
 


For the azimuth angle for sunrise and sunset you can use this site : http://www.sunearthtools.com/dp/tools/pos_sun.php
You can set the location and date and it will provide azimuth angles for sunrise and sunset.
You can set the location and date and it will provide azimuth angles for sunrise and sunset.

Revision as of 23:31, 6 July 2015

A Heilodon is a model of the suns movement across the earth. There are many different types of heilodons that you can make. Some models can show the suns movement for all latitudes and longitudes and during all das of the year. This page will describe how to make a simple heilodon for a set longitude and latitude and a set day for twelve months.

You will need a protractor, a thick poster or cardboard, wire, wire snipers, a pencil, a calculator with SIN and COS functions and Internet access.

To begin you will need to pick a location and find the latitude and longitude of that location.

On your cardboard or poster, make a perfect circle and make north, south, east and west. Also, mark the angles for north and south to use later. Directly north is angle 0 degrees and directly south has an angle of 180 degrees. Solar noon will occur along the line connecting the north to the south.

You will need to calculate the altitude angle for Solar Noon for your location using the latitude of your location and for the 21st of every month you can use the table provided. If you want to use a different day of every month, here is a complete table of declination: http://www.wsanford.com/~wsanford/exo/sundials/DEC_Sun.html

January February March April May June
(-20°05') (-10°52')
(0°00')
(+11°39') (+20°04') (+23°26')
July August September October November December
(+20°36') (+12°19')
(+0°57')
(-10°29') (-19°47') (-23°26')


If your latitude is north of the equator you will subtract the declination angle from your latitude angle. If the value is negative that is how many degrees up from the marked north line your altitude will be. If your value is positive, that is how many degrees up from the marked south line your altitude will be.


Equation for 18 degrees north

June 15th

18° - (+23°26') = -5°26' Solar noon will be 5°26' towards the north from perpendicular from the center of your circle.


December 15th

18° - (-23°26') = 41°26' Solar noon will be 41°26' towards the south from perpendicular from the center of your circle.


If your latitude is south of the equator you will add the declination angle to your latitude angle. If the value is negative that is how many degrees up from the marked south line your altitude will be. If your value is positive, that is how many degrees up from the marked north line your altitude will be,

Equation for 18 degrees south

June 15th

18° + (+23°26') = 41°26' Solar noon will be 41°26' towards the north from perpendicular from the center of your circle.


December 15th

18° + (-23°26') = -5°26' Solar noon will be 5°26' towards the south from perpendicular from the center of your circle.


For the azimuth angle for sunrise and sunset you can use this site : http://www.sunearthtools.com/dp/tools/pos_sun.php You can set the location and date and it will provide azimuth angles for sunrise and sunset.

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