But astrology can be used for so much more, as it has been in previous times. Expanding one’s understanding and use of transits is a good way to get more out of astrology. A “transit” is what astrologers call a specific, time-limited celestial event with a noticeable effect here on Earth. For example, Mercury always affects communication, thought, and short-range travel; it’s always influencing these things, and so this cannot be called a transit.