TenForward: Where Every Vulcan Knows Your Name

As long as we're talking an actual horoscope, not the lazy bullshit that you find in newspapers, you have a large number of variables with intricate relationships and various degrees of importance. These can be interpreted in various ways - often completely opposite, meaning any given configuration can fit most if not all situations of one's life. This is the same for other kinds of divination - tarot, palm reading etc.

The trick to reading it is to focus your conscious mind on the rules and leave your subconscious to pick among the ambiguities according to a deeper understanding of your situation free from conscious biases (or, when reading for others, picking up on subtle cues that you wouldn't notice or interpret correctly consciously). You basically lean into the illusion that you're reading the horoscope in the one possible way according to the rigid rules while you're actually tapping into your subconsciousness to pick on things that would otherwise either not occur to you or which you'd rationalise away.

It works surprisingly well even if both parties are aware that this is the approach the reader is taking, much like the placebo effect works even on people who know what placebo is. It will, of course, not tell you about future events, but it's a great tool to look into a particular situation, work out your feelings about it and perhaps even suggest a good way of dealing with stuff.

Anyway, in space it would work exactly the same as on Earth since the input data is largely irrelevant to the divination, though being aware of the extra impossibility could affect the reading, so if you find yourself in deep space, I'd definitely recommned using tarot instead.