tonight the solstice, the reason for the advance

The summer solstice arrives this evening, at 10.51pm Italian time: it is the moment of the year in which the northern hemisphere is most stretched towards the Sun. In the northern hemisphere of the earth it marks the beginning of the astronomical summer while in the southern one it begins the astronomical winter. It usually arrives on June 21st but there are occasional exceptions: this year’s is the earliest since 1796. In 1975 the solstice fell on June 22nd and it may even arrive on June 19th, as will happen ‘ in 2488. The date may vary because the Earth does not revolve around the Sun in 365 days. It takes exactly 365 days, 5 hours, 48 ​​minutes and 45 seconds to complete its revolution around the Sun. Since the summer solstice is the moment (and not the day) in which one of the Earth’s hemispheres reaches its maximum inclination towards the Sun, it may happen that that day, due to the time of the Earth’s revolution, does not always fall on June 21st. This gap is also at the origin of the need to have a leap year every 4 years. In fact, the solstice falls on June 20, typically in leap years, as happened in 2020 and will happen again in 2028. (AGI)Sar