What the zodiac actually is

Seen from Earth, the Sun traces a particular path across the sky over a year. That path is the ecliptic. The zodiac is that path cut into 12 equal slices — 30 degrees each.

The common mix-up

Here is what usually gets confused: the slices are named after constellations but they are not the constellations. Real constellations are not equal in size — Virgo is huge, Scorpio is small. The zodiac slices are mathematically equal.

Where the zodiac starts

The zero point is the spring equinox — the moment day and night are equal. That is the start of Aries, and the count runs from there. This is why the astrological year starts in March, not January.