Summer Solstice – OAN
MADRID, June 18 (EUROA PRESS) –
The summer solstice occurs when the Sun reaches maximum declination (minimum on the winter solstice from the northern hemisphere), projecting its light over the maximum geographic latitude on Earth.
This year such a circumstance will occur this Thursday, June 20, at 20 hours 51 minutes UTC according to calculations of National Astronomical Observatory. This season will last approximately 93 days and 16 hours, ending on September 22 with the beginning of autumn.
The beginning of summer in the northern hemisphere coincides with the beginning of winter in the southern hemisphere.
The beginning of the seasons is given, by convention, by those moments in which the Earth is in certain positions in its orbit around the Sun. In the case of summer, this position occurs at the point of the ecliptic in which The Sun reaches its most northern position.
The day this happens, the Sun reaches its maximum North declination (+23º 27′) and for several days its maximum height at noon does not change; This circumstance is also called the summer solstice. At this moment winter begins in the southern hemisphere.
The day of the summer solstice corresponds to the longest day of the year. Around this date are the day on which the Sun rises earliest and the day on which it sets latest. A circumstantial fact not related to the seasons also occurs at this time: the day of aphelion, that is, the day on which the Sun and the Earth are furthest from each other throughout the year. This year it will be July 5.
It is this greater distance from the Sun that causes the Earth to move more slowly along its elliptical orbit during the summer (according to what is known as Kepler’s second law) and therefore the duration of this season is longer than others.
The beginning of summer can occur, at most, on three different dates on the calendar (June 20 to 22). Throughout the 21st century, summer will begin on June 20 and 21 (official Spanish date), with its earliest beginning being in 2096 and its latest beginning being in 2003. The variations from one year to the next are due to the way in which the sequence of years according to the calendar (some leap years, others not) fits with the duration of each orbit of the Earth around the Sun.
