On June 21, 2013, at exactly 7:04 a.m. peninsular official time, summer began for the inhabitants of the northern hemisphere and winter began for those who live in the southern hemisphere. Why exactly at a certain time? What determines it? We explain it to you.
Since time immemorial, the position of the Sun and the stars in the sky has been studied, which has marked prophecies, religions and predictions of all kinds. In this type of analysis, the so-called ecliptic length is of particular relevance. It is basically about the position and the path that the Sun (apparently) travels in the sky throughout the year.
As they explain to us from the Madrid Planetarium, "this path is measured in angular degrees, having its origin (zero degrees) at the place where the ecliptic cuts the celestial equator (projection of the Earth's equator on the sky)." Well, summer begins exactly when the Sun is at 90º of ecliptic longitude . On the day that summer begins, the sun reaches its maximum north declination (+ 23º 27 ') and its maximum separation towards the north of the celestial equator and for a few days it will remain at the highest height of the whole year, in the middle of the summer solstice.
In the representation offered by the Madrid Planetarium, the sky of the capital of Spain is shown at 2:17 p.m. peninsular time, exactly 14 hours and 13 minutes after the beginning of summer.
