Enter a recorded local time, historical UTC offset, and birthplace longitude. The result gives both ends of the meridian axis and a small time-sensitivity table.
Open the free calculator →The meridian, not the top of the sky
Medium Coeli, usually shortened to MC, is the upper intersection of the local celestial meridian with the ecliptic. The meridian is the north–south great circle through the observer’s zenith. The MC is a point on the zodiac; the zenith is directly overhead, and the two are not interchangeable. The opposite intersection is the Imum Coeli (IC).
Every zodiac degree rotates across the local meridian over a sidereal day. That is why a calendar date alone cannot identify a natal MC degree. A precise birth time and the birthplace’s east–west longitude are required. A one-hour shift can move the MC by many degrees, and the exact zodiac change is not constant because the ecliptic is tilted relative to the celestial equator.
How it relates to houses
In many quadrant-house systems the MC is the tenth-house cusp and the IC is the fourth. Equal House and Whole Sign use other cusp definitions, so the MC can sit within a house instead. The angle itself does not change when you switch the house system; the house label can. Avoid reading “MC sign” and “tenth-house sign” as universally identical.
Reading an MC placement
Astrological interpretation often associates the MC with public visibility, vocation, and the direction in which a life seeks expression. Those are symbolic readings, not measured traits. First confirm the recorded time and offset, then read the MC alongside the rest of the chart. If the birth hour is unknown, interpret a time-sensitive MC only as an open question.