If long enough, for example, in the year to monitor the situation of the sun, we can see that its height above the horizon at different days will be unequal: the largest – June 22, while the lowest – 22 December. These days are called days of summer and winter solstices. Twice a year, on 21 March and 23 September, the sun rises at the east (at the intersection of lines of the horizon and the celestial equator, or more precisely, the equator and the ecliptic), and comes just at the west (also on crossing the line just to the west). These days it is above and below the horizon the same time (that is, the day is night), and therefore they are called days of vernal and autumnal equinoxes. Between March 21 and September 23 the sun rises north east of the point and, conversely, between September 23 and March 21 – south of it. These four dates: March 21, June 22, September 23 and December 22 – all, of course, are well known. It is in these days in the northern hemisphere begins (in the astronomical sense), spring, summer, autumn and winter. If the cause of the Sun on the celestial sphere, we obtain a circle.
This is a great circle, representing the celestial sphere visible path of the sun among the stars during the year called, as already mentioned, the ecliptic, the plane in which it lies – the ecliptic plane. Along this circle are the zodiacal constellations, which are mainly the names of real or mythical animals. Division of the zodiac begins with the vernal equinox, March 21. Each sign is approximately 30 days, ie, that period of time during which the Sun (relative to the Earth) moves to the corresponding 1 / 12 of celestial ecliptic. Now a few words directly to the zodiac. If we divide the ecliptic, starting from the vernal equinox, in the course of the sun, into 12 equal parts, you get 12 sectors of the celestial sphere. This is zodiac: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces.