Movement of the Sun

Passive solar design is based on utilizing the sun’s heat energy and its predictable movements through the seasons.

As the Earth rotates around the sun on its annual cycle, it is tilted at an angle on its vertical axis.  This impacts how the sun’s rays strike various locations on Earth.  The Earth is its most extreme tilt at the winter and summer solstices.

The sun appears to rise in the east and it sets in the west. In actuality, the Earth is rotating on its axis and around the sun.

 

Here is a diagram that compare the sun’s path on the winter and summer solstices.

A diagram of the sun’s path on the winter and summer solstices, Courtesy of DOE

This affects how low or high the sun appears in relation to the horizon.

In the winter, the sun is relatively low in the sky with its lowest arc through the sky on the winter solstice, on December 21st.

In the summer, the sun travels a high path through the sky and is at its highest angle on the summer solstice, on June 21st.

The equinox falls on the point between the solstices and indicates the arrival of spring or fall.

 

Justin Quinnell's pinhole timelapse photography of sun travel

Artist Justin Quinnell strapped a pinhole camera to a lightpole for one year.

This picture shows the sun’s path throughout the year. The highest arc represents the sun’s path on the summer solstice, while the shortest, lowest arc is the sun’s path on the winter solstice.

On each equinox, the sun travels a path that is right in the middle of the path that it travels on the solstices.

March 21st – Vernal Equinox

June 21st – Summer Solstice (highest path)

Sept 21st – Autumnal Equinox

Dec 21st – Winter Solstice (lowest path)

 
 

Passive solar design uses the predictable movements of the sun to best utilize its energy within the building’s overall design both for heating and cooling purposes.  Many passive solar buildings also include active solar aspects, such as photovoltaic panels, as shown on the roof in the first diagram located at the top of this post.

 

 

 

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9 Responses to Movement of the Sun

  1. Sayed Qasim azim December 2, 2014 at 6:07 am

    We are loosing the safe distance from the sun gradually.

  2. Keya Lea December 10, 2014 at 9:46 am

    Very, very, very slowly… but in the meantime, why not harness its power? 🙂

  3. Serbest December 30, 2015 at 11:29 pm

    THANKS , IT WAS VERY USEFUL .

  4. Michael March 6, 2016 at 9:01 am

    What is the ideal angle to have solar panels in Louisville to maximize their efficiency?

    Seems to me it would be at wherever the sun is around noon at a month from the summer solstice?

  5. Keya Lea March 6, 2016 at 9:09 am

    Michael, not sure which Louisville you are located in, but because the globe is a big place, depending on longitude and latitude, the precise ideal angle will differ. The ideal angle for solar panels will also change through the seasons.

    Here’s a resource that might be able to help you: http://www.solarpaneltilt.com/

  6. Michael March 6, 2016 at 12:17 pm

    Oh, sorry. Louisville Ky.

    Where we are the summer solstice angle of the sun is about 75 degrees from horizontal. Our cloud cover is less in summer than the other seasons. The panels will be fixed, unfortunately. (Funny how a plant’s leaves will move to maxamize sun-catching for free).
    I would think I would want them at somewhere between 60 and 70 degrees?

  7. Michael March 6, 2016 at 12:21 pm

    And… I just read the linked article. Never mind, that has what I am looking for.

    Thanks for the link.

  8. Stephen Kosciesza March 23, 2016 at 1:58 pm

    I believe the diagram is mistaken in one detail. The circle that is the path of the sun will indeed be farthest north on June 21 and farthest south on December 21. But the circle itself (not where we see the sun) will always form the same angle to the (apparently, to an observer on earth) flat plain of the ground. To put it another way, the two circles, and all circles in between will be parallel to each other.
    By the way, one might have added another circle. That would be half way between the two already there (and parallel to them both, if the two give were shown correctly). They would cross the horizon exactly east and west. That would show the path on both March 20 and September 20, the beginning of (northern) spring and fall, respectively.

  9. Master wilbert boucher November 23, 2016 at 11:49 am

    Every thing from streetlights and the way cities light up at night this type of harnessing is what I see for the future some people who are visual find it easy to help our economy and help our future with the suns rays and eventually all energy

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