AN INTRODUCTION TO THE ZODIAC

The Zodiac are a group of constellations. Their special designation is due to the fact that they lie in the background of the plane of the solar system.

The solar system is virtually a flat or two-dimensional like a round table top as opposed to spherical or ball shaped. This means that as we are inside the solar system this plane manifests as a line across the sky which the sun, moon and planets all move along (although the moon and some planets do stray slightly above or below it at times). We call this line the ecliptic. The stars which happen to lie in the background of the ecliptic, having been formed into groups, make up the constellations through which the sun, moon and planets appear to be moving.

What is a Constellation?

For the purposes of science and general practicality the entire sky is divided up into areas known as constellations. Each of the 88 official constellations has a pattern of stars, each of which may or may not roughly resemble the figure it was named after. Each also has an official boundary where anything inside this boundary is said to be ‘in’ this constellation.

The 13 Constellations of the Zodiac

While commonly known as being a collection of 12 constellations, there are actually 13 constellations which lie in the background of the ecliptic. The 13th and often overlooked star group is Ophiuchus which is tucked in below the tail of Scorpius and beside Sagittarius. All zodiac constellations are not of equal length therefore the sun spends different amounts of time in each one. While the sun will only be in Scorpius for 9 days it will spend 45 days in Virgo.

While Scorpius is probably the only constellation that actually looks like its namesake, some others are still easy to pick out. Leo with its large, bold triangular shapes of bright stars can vaguely resemble a sleeping lion, the ‘A’ shape of the Hyades cluster can pass as the nose of a bull and Gemini sports two bright stars as the heads of the twins with discernible star trails leading off them marking the bodies. Cancer and Capricorn contain only dim stars making picking out any pattern very difficult. While many of the stars of Sagittarius are very bright, the pattern is so abstract that it is very hard to see the half-man half-horse of its Greek mythology. Instead, Sagittarius bears some resemblance to a teapot.

Sun, Moon, Planets and the Zodiac

While the stars never change position (at least not noticeably over the course of our lifetimes), the sun, moon and planets do move against the backdrop of stars as they move in their orbits or we move relative to them. So when a planet appears to be in the foreground of a certain constellation it is said to be ‘in’ that constellation. The constellation that the sun was in at the time you were born is said by astrologers to be your sun sign or star sign, however this has become inaccurate due to the effects of precession.

Become Familiar with the Zodiac Constellations

From an astronomical point of view the zodiac has nothing to do with telling fortunes. They are patterns made out of stars lying in the background of the plane of the Solar System. A familiarity with the star patterns of the zodiac constellations is very handy for a sky watcher. As these are the constellations that the planets move through, they are essential in describing planetary and lunar positions. They are also a very handy reference for getting to know the workings of the night sky as well as understanding monthly and seasonal change with regard to celestial objects.