As romantic as it is to believe your go-to astrologer makes their predictions with little more than a crystal ball and their intuition, that, sadly, is just not how astrology works. More accurately, astrologers are generally working from a laptop, poring over a table of planetary positions known as an ephemeris.
This handy tool is essentially a map of the night sky. It's based on astronomical models and calculations of how the planets move, and it displays years' worth of planetary activities as they occur daily. And it's with this information that astrologers make their predictions. Nowadays, ephemerides are usually generated using software, but they're said to have been distributed as early as the 4th century BCE.
You may think that this sounds like some sort of cheat sheet, but that's probably because you haven't spent much time trying to read an ephemeris yourself. Open one up and prepare to be mystified — to actually understand the thing, you'll need to do some math.
That's because an ephemeris doesn't spell out the planets' positions for you. Instead, it lists their placement by degrees on the Wheel of the Zodiac so that astrologers can see where a planet is in relation to each of the 12 signs, plus where it's headed next (you have an ephemeris to thank for any long-term predictions you read in your horoscope).
For example, on January 1, 2018, Uranus was in Aries at 24 degrees. This tells an astrologer that it'll still be a while before this slow-moving outer planet heads into the next sign on the Wheel (Taurus). And until that happens, you can expect old desires for adventure to bubble up, and to feel a bit more combative than normal (such is the influence of this dynamic-yet-mysterious sign-planet combo).
Like we said, though, it's pretty hard to understand an ephemeris if you haven't studied astrology. An accurate astrological reading is the product of years of study and research. Even if your astrologer prefers to use a software program to pull up the exact movements of a specific planet, learning to read an ephemeris — and using it regularly — was absolutely part of their training.
And hey, if you'd still like to think of the horoscope-writing process as far more esoteric than a set of calculations would make it seem, we're sure your astrologer would appreciate the gift of a crystal or two for their desk.