solstice and equinox mark the beginning of seasons of the year and are related to incidence of the sun's rays and the Earth tilt. Due to the Earth's axis of rotation and its position relative to the sun, the incidence of light on the hemispheres is different. These astronomical phenomena then represent the apparent motion of the Sun and both occur twice a year in each hemisphere.
Read too: What would happen if the Earth stopped rotating?
difference between solstice and equinox
In each hemisphere, the solstice and equinox astronomical phenomena occur on different dates and mark the beginning of the seasons.
→ Solstice
The solstice represents the positioning of the sun at its maximum limit, that is, the Sun will be at its peak in the north or in the south. This greater declination of the Sun in relation to the Equator has the consequence of greater illumination of one of the hemispheres. This phenomenon occurs at two times of the year, in June and in December.
When the solar incidence is greater in one of the hemispheres, the
solstice in summer. When the solar incidence is lower in one of the hemispheres, however, the Winter Solstice. The summer solstice is characterized by having the daysmostlong than the nights. At the solstice in Winter, at nightsthey are most long than the days.North hemisphere |
South hemisphere |
|
Summer Solstice: starts in the month of June. The Sun shines perpendicularly on the Tropic of Cancer. - June 20th and 21st |
Summer Solstice: starts in the month of December. The Sun shines perpendicularly on the Tropic of Capricorn. - December 20th and 21st |
|
Winter Solstice: starts in the month of December. The Sun shines perpendicularly on the Tropic of Capricorn. - December 20th and 21st |
Winter Solstice: starts in the month of June. The Sun shines perpendicularly on the Tropic of Cancer. - June 20th and 21st |
→ Equinox
The equinox represents the average position of the Sun in relation to the Earth, that is, none of the hemispheres is inclined in relation to the Sun, its rays being directly on the Equator, thus illuminating the two hemispheres equally. This phenomenon occurs at two times of the year, in March and in September.
The occurrence of the equinox begins the spring and to autumn. Due to the same intensity of the sun's rays in both hemispheres, the days and nights have the same duration.
North hemisphere |
South hemisphere |
|
Spring Equinox: starts in the month of March. - March 20th and 21st |
Spring Equinox: starts in the month of September. - September 22nd and 23rd |
|
Autumn Equinox: starts in the month of September. - September 22nd and 23rd |
Autumn Equinox: starts in the month of March. - March 20th and 21st |
Dates of the solstices and equinoxes
Check the dates of the solstices and equinoxes in 2019:
Dates of the 2019 solstices and equinoxes in the Northern and Southern Hemispheres.
Read too: What is daylight saving time?
The relationship between solstices and equinoxes and the seasons of the year
At seasons they are the result of the Earth's axis of inclination in relation to the movement that the planet makes around the Sun. Because of the inclination in relation to the orbital plane, the solar incidence is not equal for the two hemispheres.
This greater or lesser heat stroke in each hemisphere is responsible for the existence of seasons, which do not occur simultaneously in each of them. While in the Northern Hemisphere it is winter; in the Southern Hemisphere, it's summer. In the same way that while in the Northern Hemisphere it is spring; in the Southern Hemisphere, it's autumn, and vice versa.
Read more:Why do autumn leaves have a specific color?
The astronomical phenomena solstice and equinox mark the beginning of each season in each hemisphere. When the Sun reaches its maximum limit in the North or the South, the summer and winter solstices occur. When the sun falls on the Equator, being in its middle position, the spring and autumn equinoxes occur.
→ Date of the seasons of the year in the Southern Hemisphere
2020 |
|
Autumn Start: March 20, 2020 at 00:50 |
|
Winter Start: June 20, 2020 at 6:44 pm |
|
Spring Start: September 22, 2020 at 10:31 am |
|
Summer Start: December 21, 2020 at 7:02 am |
Earth rotation and translation
THE Earth performs two movements, the movement of rotation and translation.
- Rotation: it is the movement performed by the Earth around its own axis. It lasts approximately 24 hours, marking the occurrence of days and nights.
- Translation: it is the movement performed by the Earth around the Sun. It lasts approximately 365 days, allowing the existence of the seasons of the year.
by Rafaela Sousa
Graduated in Geography
Source: Brazil School - https://brasilescola.uol.com.br/geografia/solsticios-equinocios.htm