Solstices and equinoxes

earth orbiting the sun

We know that the Earth has several movements that are those of rotation and translation. By this we mean that due to these movements, there are solstices and equinoxes. An equinox is a time of year when the sun is located exactly above the equator, so it is positioned over the zenith. This means that the day and the night have almost the same duration. The opposite occurs with the solstice.

In this article we are going to tell you all the characteristics and differences between solstices and equinoxes.

What are the solstices and equinoxes

solstices and equinoxes


The first of all is to know what the solstices and equinoxes are. An equinox is when the sun is located on the equator and the day lasts the same as the night. That is, they last approximately 12 hours. This happens twice a year, around March 20 and September 22. This coincides with the onset of spring and fall in some regions.

If we divide the planet into two halves, one is illuminated by sunlight and the other is obscured. In one we have the day and in the other the night. The dividing line passes right through the poles. This occurs because during the equinoxes both poles are not tilted towards or away from the sun. It doesn't always happen on the same day. They have a margin of several days. This is because the length of the years is not always the same. Remember that every 4 years if you add one more day to the calendar because it is a leap year. During the equinoxes the sun is located at one of the two points on the sphere where the celestial equator and the ecliptic intersect. This corresponds to a circle in the same plane as the equator. That is, the projection of the terrestrial equator is the celestial sphere.

The vernal equinox happens when he only moves north in the plane of the ecliptic and crosses the entire celestial equator. Here we see that the spring season begins in the northern hemisphere. On the other hand, the autumnal equinox happens when the sun moves across the celestial equator to the south. It marks the beginning of fall.


Solstices are events in which the sun reaches its highest or lowest point throughout the year in the sky. In a year in the Northern Hemisphere there are two solstices. On the one hand we have the summer solstice and on the other hand the winter solstice. The first takes place on June 20-21 and the winter solstice on December 22-22. During both solstices, the sun is located on one of the two imaginary lines on Earth that are known as the Tropic of Cancer and the Tropic of Capricorn. When the sun has set over the Tropic of Cancer is when the summer solstice takes place and when it is located in the Tropic of Capricorn, winter begins.

During the first solstice it is where we find the longest day of the year, while the second is the shortest day and the longest night.

Solstices and equinoxes of summer and winter

sun positions and inclined rays

Summer Solstice

It is often thought that that day, the first of the summer season, is the hottest. But it doesn't really have to. The Earth's atmosphere, the land we walk on and the oceans absorb part of the energy from the solar star and store it. This energy is released again in the form of heat; however, keep in mind that While the heat is released from the earth fairly quickly, the water takes longer.

During the big day, which is the summer solstice, one of the two hemispheres receives the most energy from the Sun of the year, since it is closer to the king star and, therefore, the rays of the mentioned star arrive more straight. But the temperature of the oceans and the land are still more or less mild, for now.

Solstices and equinoxes: winter solstice

four seasons of the year

Planet Earth reaches a point on its path where the Sun's rays strike the surface in the same way more oblique. This happens because the Earth is more inclined and the rays of the Sun hardly arrive perpendicularly. This causes fewer hours of sunlight, making it the shortest day of the year.

There is a bad idea in society in general about winter and summer according to the distance from the Earth to the Sun. It is understood that in summer it is hotter because the Earth is closer to the Sun and in winter it is colder because we we find further away. But it is totally the opposite. More than the position of the Earth with respect to the Sun, what influences the temperatures of the planet is the inclination with which the Sun's rays hit the surface. In the winter, on the solstice, Earth is closest to the Sun, but its tilt is the highest in the Northern Hemisphere. For this reason, when the rays reach the earth's surface too inclined, the day is shorter and they are also weaker, so they do not heat the air as much and it is colder.

Spring and Autumn Equinoxes

Here we must distinguish the equinoxes according to the hemisphere where we are. On the one hand, the northern hemisphere, when it is the vernal equinox we have that at the pole North a day will last 6 months, while at the South Pole, a night will last 6 months. I also have to bear in mind that autumn begins in the southern hemisphere.

As you can see, the solstices and equinoxes are mainly due to the movement of the earth with respect to the sun and the temperatures and environmental conditions depend on the inclination of the sun's rays. I hope that with this information you can learn more about the solstices and equinoxes.

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