Constellations

The constellations that astronomers use to identify parts of the sky are not the same as the Zodiac signs used by astrologers. The Zodiac signs were identical to the constellations 2000 years ago when their modern names were first used. The Signs are an astrological convenience ignoring the differences between two different types of solar calendar. This is described further in The Calendar.
The astrological signs are about a month out from the astronomical constellations. When an astrologer says the Sun is in Cancer, an astronomer will look for it in Gemini.
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