The 12 zodiacs happen to be whatever constellation the arrow is pointing at as the planet orbits the Sun.
Nearly 3,000 years ago, the signs of the zodiac were divided into 12 equal parts with 12 corresponding constellations – much like cutting into a pizza.
According to NASA, this was done by the ancient Babylonians who kept time through a 12-month calendar.
But there is a small caveat – the Babylonians knew of 13 constellations in the zodiac.
NASA said: “So they picked one, Ophiuchus, to leave out.
source: express.co.uk