To draw a diagram of the sun's path across the sky for a location at a middle latitude in the Southern Hemisphere, we will need to create a series of arcs that represent the path of the sun through the sky during the different seasons: summer solstice, autumn equinox, winter solstice, and spring equinox. Here's a step-by-step guide on how to do this:
1. First, draw a large circle to represent the celestial sphere, which is an imaginary sphere encompassing the Earth. This will be the outline of the sky from the observer's perspective.
2. Draw a horizontal line through the center of the circle to represent the horizon. Everything above this line is the sky we see during the day.
3. Identify and mark the center of the circle, which will be the zenith—the point directly overhead.
4. Since we are illustrating this for middle latitudes in the Southern Hemisphere, we need to orient our diagram accordingly:
- The sun will always be in the northern half of the celestial sphere since it is always to the north of the observer in the Southern Hemisphere.
- In this hemisphere, the sun is at its highest in the sky during the summer solstice and lowest during the winter solstice.
5. Summer Solstice (around December 21):
- Draw an arc that begins at the southeastern horizon (left of the center horizon line).
- The arc peaks near the zenith but towards the north and then descends to set at the southwestern horizon (right of the center horizon line).
- This arc should be the highest of all the arcs, as it represents the longest day of the year.
6. Winter Solstice (around June 21):
- Draw an arc that begins much closer to the northeast (left) on the horizon line.
- This arc will peak much lower in the northern sky and set closer to the northwest (right) on the horizon line.
- This arc represents the shortest day of the year, so it should be the lowest arc.
7. Equinoxes (around March 21 and September 23):
- For the equinoxes, draw two identical arcs that start exactly at the eastern point (left) on the horizon line.
- These arcs will peak due north but at a point that is mid-way in the sky between the high arc of the summer solstice and the low arc of the winter solstice.
- The arcs will end exactly at the western point (right) on the horizon line.
- During an equinox, day and night are of equal length.
8. Finish by labeling your arcs with the corresponding season:
- Label the highest arc as "December Solstice" (summer in the Southern Hemisphere).
- Label the lowest arc as "June Solstice" (winter in the Southern Hemisphere).
- Label the middle arcs as "March Equinox" and "September Equinox" for autumn and spring, respectively.
Remember, this diagram is a simplistic representation and assumes a flat horizon and no atmospheric effects (like refraction). Therefore, while the arc directions are generally correct, the actual sun paths as seen by an observer may differ slightly.
