The Northerly point of culmination of a sign of the zodiac for a particular time as viewed from a particular location.
The literal translation of Medium Coeli (abbreviation: MC) is "middle of sky". The Imum Coeli lies opposite the Medium Coeli.
The Imum Coeli, the midnight point, represents the lower point of intersection between the meridian and the ecliptic. It should not be confused with the nadir. As is the case with the other axes, all the signs of the zodiac cross the Imum Coeli in the course of one day.
As the lowest point in the horoscope, the Imum Coeli symbolises the area of life in which an individual is all alone. It is the place of greatest intimacy but also of greatest vulnerability. Here are the roots of the personality in both the literal (family) and figurative sense (soul) and the archetypal pattern. This is the point at which one can best allow oneself to fall or let go. Hellenistic astrologers considered the IC to be the home of the underworld, or Hades.
The ideas symbolised by the Imum Coeli often remain unconscious because they have been so familiar to us since early childhood. It stands for the past, in contrast to the Medium Coeli which symbolises the future.
The sign of the zodiac on the Imum Coeli indicates an individual's true nature deep down inside and the quality of their innermost needs and feelings.
In Quadrant House Systems the Imum Coeli marks the beginning of the fourth house, and is associated with the Moon as its Natural House Ruler in modern astrology.