The twelve signs

Read across a row to see a sign's basic make-up. The ruler shown first is the traditional one; three signs gained a modern ruler after the outer planets were discovered, and most astrologers today consult both. Opposite signs share a modality and sit 180° apart, an Opposition, so each pair forms an axis of complementary themes.

Western astrology uses the tropical zodiac, which is tied to the seasons: Aries always begins at the March equinox, Cancer at the June solstice, Libra at the September equinox and Capricorn at the December solstice. About two thousand years ago those points lay among the stars the signs are named after. Because Earth's axis slowly wobbles, a motion called precession, the equinox drifts backwards against the stars by about one degree every 72 years. Today the tropical signs and the constellations of the same names are offset by roughly 24°.

The sidereal zodiac, used in Vedic astrology, keeps the signs fixed to the stars instead, so most planets fall about one sign earlier there. Neither system is a mistake; they measure different things, one the cycle of the seasons and the other the background of stars. The constellations themselves are different again: astronomers drew them with unequal boundaries, and the Sun also crosses Ophiuchus, which is a constellation but not a sign. Everything on stars.guide uses the tropical zodiac unless it says otherwise.