Today in the Northern hemisphere of our planet the day of the summer solstice. This means that the daytime today will last longer than any other day. In Moscow, for example, the Sun began to rise over the horizon at 3:45 and sunset will come only in 21:18. In the southern hemisphere today, by contrast, should be the shortest and night the longest
The summer solstice can fall on June 20 (usually in leap years), or June 22, but on June 21 it occurs most often. The height to which the Sun will rise today above the horizon, the Northern hemisphere will be maximum and South minimum for the entire year. During the several days before and after June 21, shone in the afternoon is almost the same height, although in other periods of the year, the figure is changing somewhat rapidly. That is why the designation today used the word “solstice.” On the North and South poles of the Earth, today it was the middle of the long months of polar day and polar night respectively.
In many countries there is a tradition of, or otherwise associated with the onset of the longest day of the year, though they rarely coincide with the “astronomical” the exact date. In particular, from the evening of 23 June (6 July new style) and 24 June (7 July) marks the national holiday of the Eastern Slavs Ivan Kupala. In Sweden, Latvia and some other countries the summer solstice is officially considered a holiday.
Tomorrow day in the Northern hemisphere will begin gradually to decline, and in South to increase. On September 22, will have the spring equinox, when day and night on Earth lasts almost equally (if not to take into account the effect of atmospheric refraction, which day will be slightly longer), and on December 21 — the winter solstice.