On June 21, at 20:06 local hour, will occur the summer solstice that marks the beginning of the summer in the northern hemisphere and that of the winter in the southern hemisphere. So this Thursday is going to have the longest day and the shortest night of the year. From the etymological point of view, “solstice” means “Sun standing still”. According to the astronomers, in the period around the summer or the winter solstice the height of the Sun above the horizon seems to remain unchanged. At this date the gradient of the Sun’s movement in relation to its declination changes. The Sun is in his culmination above the horizon, the day will have the biggest duration of the year, of about 15 hrs 32 min, and the night will last for only 8 hrs 28 min. The Gregorian calendar is designed so that the seasons begin at almost the same date. In this calendar, created in 1582, the summer solstice can take place on June 19, 20, 21 or even 22.