Everything in the solar system is in constant motion. Astrology describes lived experience in the context of that motion.
Astrology and astronomy were one discipline for thousands of years
Until the 1700s, studying how the stars move (what we now call astronomy) and studying how the stars affect us (what we now call astrology) were the same job. Astrology places a person's life inside a vast universe that never stops moving.
We start with astronomy
At school you learned that the Sun sits at the centre of the solar system. But until the 1500s people assumed the Earth was the centre.
Both models describe the motion of the Sun and the planets correctly; both are valid representations. Astrology looks at the sky from Earth's perspective.
The zodiac
The zodiac is a ring of constellations that sits in the same plane as our solar system. There are dozens of other constellations, but only these twelve are the ones the planets appear to pass in front of.
Over days (or months and years, depending on the planet), each planet moves across the sky; it appears in front of one sign, then the next. Once it has passed all twelve it has completed a full lap and starts again.
So what does that mean?
Late at night, you look up. In front of a group of stars that looks like two cheerful figures holding hands, there is a menacing red ball. You have seen this before — in fact, you see it every two years.
Around that time your own "red" energy, like two years ago, feels a little more playful and light. Could the red ball be linked to anger and aggression? The two figures holding hands to mischief and play?