Why does the azimuth of the sun change

Again, the seasonal changes in climate are caused by the varying angle of the sun's rays, together with the varying amount of time that the sun is above our horizon. Although we never see the sun and the stars at the same time, it's not especially hard to figure out which stars and constellations the sun is lined up with on any given day: Just look at the constellations in the east a little before sunrise, or the constellations in the west a little after sunset, and allow for the angle of the sun below your horizon.

The ecliptic is a great circle on the celestial sphere, tipped Its orientation with respect to our horizon changes as the sphere spins around us each day. It has the orientation shown here at noon in December and at midnight in June. If you plot the sun's daily location on a star chart or celestial globe, you'll find that it gradually traces out a great circle, called the ecliptic. So the ecliptic is an imaginary circle around the celestial sphere, centered on us, that marks all the possible locations of the sun with respect to the constellations.

Each day, as the sun takes four minutes longer than the constellations to spin around us, it creeps approximately one degree eastward along the ecliptic. It completes the circle in exactly one full year The ecliptic intersects the celestial equator at two opposite points, the sun's locations at the equinoxes. But the ecliptic is tipped at a The sun reaches the ecliptic's northernmost point at the June solstice, and reaches its southernmost point at the December solstice.

The constellations of the zodiac are simply those that happen to lie along the ecliptic. According to the modern official constellation boundaries, however, most of the Scorpius portion of the ecliptic actually lies in the adjacent constellation Ophiuchus.

In this degree map of the entire celestial sphere, the north celestial pole is stretched across the top edge and the south celestial pole across the bottom edge. The celestial equator is marked in blue, and the 12 constellations of the zodiac are outlined. The ecliptic, shown in yellow, marks the sun's annual path among the stars. At the March equinox the sun is at the far right, in Pisces.

The sun drifts leftward by about one degree per day, moving first into the northern half of the sky and then, after the September equinox, into the southern half.

The sun's location with respect to the stars doesn't depend on your observing location on earth, so you now know enough to figure out how the sun appears to move through the sky from other locations. If you travel east or west, you'll see the sun rise and set earlier or later, respectively, just like a star would. Again, we partially compensate for this by setting our clocks to different time zones. If you travel north or south, the sun's daily motion is still the same as that of a star seen from your latitude.

So at the equinoxes, for example, the sun still follows the celestial equator, while at the solstices, the sun follows a circle that lies If you can visualize the paths of stars on these parts of the celestial sphere, then you can visualize the daily path of the sun.

So, for example, as you travel northward from Utah, you'll see the noon sun get lower and lower in the southern sky. Eventually you'll come to a latitude where the noon sun at the December solstice lies on your southern horizon; this latitude, North of the Arctic Circle there will be days around the December solstice when the sun never rises.

What's a little less obvious is that at the Arctic Circle on the June solstice, the sun never sets—it merely grazes the northern horizon at midnight see the illustration below.

Still farther north there will be more and more days of darkness in winter and continuous sunlight in summer. At the North Pole, the sun is above the horizon for six straight months March through September , spinning around in horizontal circles, reaching a maximum height of As you travel southward in the northern hemisphere, the noon sun gets higher and higher.

The first qualitative change occurs at This latitude is called the Tropic of Cancer. Farther south, in the so-called tropics, the noon sun will appear in the northern sky for a period of time around the June solstice. Now, if the Sun were to be directly above the equator which corresponds to the equinoxes , then it will rise exactly at east.

When the Sun is north of the equator, then it will rise at an azimuth north of exact east and when it is south of equator, it will rize at an azimuth south of exact east. As the Earth goes around the Sun, the Sun appears to go in a cycle from equator to north of equator and then back to equator and then to south of equator and then back again to equator which marks the cycle of the seasons on Earth.

Hence, the azimuth of sunrise changes slowly from direct east to north of east and then back to east to south of east and then back again to east. Thank you for answering my question before about the azimuth, but I was wondering, does the azimuth of the sunrise position change at a uniform rate throughout the year? No, the change in azimuth is not uniform. If the Earth's orbit were exactly circular, then the change in azimuth will be sinusoidal.

It would change slowest during solstices where the sunrise is most towards north or south and fastest during equinoxes where the sunrise is towards exact East. However, Earth's orbit around the Sun is not an exact circle.

It is slightly elliptical with the perihelion where the Earth is closest to the Sun occuring near winter solstice Jan. Hence, the change in sunrise position will not be an exact sinusoid and will change slightly faster around winter solstice compared to summer solstice. This effect is small though. Jagadheep built a new receiver for the Arecibo radio telescope that works between 6 and 8 GHz. He studies 6.

These masers occur at sites where massive stars are being born. He got his Ph. Why does the location of sunrise change? Intermediate Why does the azimuth of the sunrise position change over the course of the year? This page was last updated June 28, About the Author Jagadheep D. Pandian Jagadheep built a new receiver for the Arecibo radio telescope that works between 6 and 8 GHz.

Similar Questions that might Interest You How much can the location of sunset differ from due West? Intermediate How does the location of sunrise and sunset change throughout the year? Advanced Why is the Moon higher in the sky in winter and lower in the summer?

Learn more about how sun and moon information is displayed on the Planner watching the following video tutorial:. For us, the elevation of the sun is the angle between the direction of the geometric center of sun's apparent disk and the observer's local horizon. The following two pictures show the elevation of the sun in two different positions of the observer.

The best way to learn how to calculate and set the azimuth and the elevation you need is by having a look at a few real examples. The following video tutorials will teach you how to do it for different situations, step-by-step:. In conclusion, mastering azimuth and elevation will give you the power to plan any photo you imagine with sun and moon, including: a full moon setting under a secret stone arch, a sunrise between two giant rocks located on a magic beach, a sunset over the main street in your hometown or a dramatic full moon appearing from behind a nearby hill