Each of the 12 signs of the zodiac has an affinity with one of the heavenly bodies. The energy of that planet works well with the characteristics of the sign.
Prior to the discovery of the outer planets (Uranus, Neptune, Pluto), each of the visible planets ruled two of the signs, with the Sun and Moon associated with Leo and Cancer, respectively. Only Mercury and Venus continue to have rulership over two signs.
Click on any sign or planet to learn more about these important pairings.
rules Aries
rules Taurus 
rules Gemini 
rules Cancer 
rules Leo
rules Scorpio
rules Sagittarius
rules Capricorn
rules Aquarius
rules Pisces