Why the Sun rises in the East and sets in the West

It is always said that the Sun rises in the East and sets in the West , but in reality this fact only happens twice a year . This is due to the inclination of the Earth’s axis and its translational movement around the Sun. The days in which this occurs coincide with the equinoxes , which are the days in which both the day and the night have the same duration. The rest of the year, the point where the Sun rises and sets is shifted slightly to the north during the spring and summer and in the fall and winter, to the south. In the southern hemisphere, this shift is just the opposite.

The maximum point of this displacement is reached at the summer and winter solstices . In the Northern Hemisphere, the winter solstice is the shortest day of the year and the Sun is at its lowest point on the horizon during its zenith and the summer is the longest of the year with the Sun at its highest point. high above the horizon. This situation is the other way around in the southern hemisphere. In this displacement the two highest points reached are marked by the Tropic of Cancer and the Tropic of Capricorn.

What actually happens is that by agreement it was established that the cardinal point through which the Sun rises is the East and sets in the West, but, as we said, the perfect coincidence with these points is reached only twice a year.

Learn more about it with this other post of AgroCorrn about why the Earth revolves around the sun .

Given that all the planets in our Solar System revolve around the Sun and in the same sense that our planet does, the logical thing would be to think that the Sun rises in the East and sets in the West on all planets. However, this is not the case since this convention is also influenced by the sense of the rotational movement of a planet on its own axis and not all the planets of the Solar System are the same , in fact it differs in two, which are Venus and Uranus.

Venus is thought to rotate in the opposite direction due to a large collision with another star. In this way, we can say that on Venus the Sun rises in the West and sets in the East (according to our system of cardinal points). On Uranus, what would happen is that its axis of rotation is so inclined that it almost coincides with its plane of translation.

For the rest of the planets it happens the same as ours, except that the closer to the Sun, the translational movement must be faster to maintain its stationary orbit. Thus, on Neptune for example, a day lasts between six and seventeen Earth hours, while on another planet like Venus it would last about 224 Earth days.

We know that all the planets in our Solar System have a rotational movement on their axis, but does the Sun also do it? Yes, the Sun rotates on itself , but not in a uniform way.

This rotates in a differential rotation (it does not rotate at the same speed over its entire surface). It takes about 24 hours for the Earth to complete its rotation and evenly, since its surface is solid. On the other hand, the Sun is a set of gases and plasma, so it rotates at different speeds depending on the areas of its surface considered, taking about 34.4 days at its poles and 25.4 days at the equator. However, since the Sun is about 109 times larger than Earth, it has a proportionally faster rotational motion.