Midheaven
The Midheaven (MC or Medium Coeli) is the point of the zodiac highest above the horizon at the moment of birth. It marks the cusp of the tenth house and is, along with the Ascendant, one of the four angles of an astrological chart.
Origin and etymology
The Latin expression Medium Coeli literally means middle of the sky, in Greek mesouranema. The concept was codified by the Hellenistic astrologers of Alexandria in the 1st century CE and systematized by Claudius Ptolemy in the Tetrabiblos in the 2nd century. The MC is identified by the passage of a celestial body across the upper meridian of the location, that is, the highest point of its apparent path. In the medieval Arab tradition, with Abu Ma'shar and Al-Biruni, and then in the Latin tradition of Guido Bonatti (13th century), the Midheaven is one of the four cardinal angles of the chart, alongside the Ascendant, the Descendant and the Imum Coeli.
Evolution and tradition
The MC was long interpreted as the indicator of reputation and status. The psychological re-reading of the 20th century, under the influence of Dane Rudhyar and Stephen Arroyo, refocused it on vocation and deep aspiration. The MC answers the question: toward what is this life publicly oriented?. Its opposite, the Imum Coeli (IC, Imum Coeli), designates by contrast the roots, the original home, inwardness. The MC-IC pair forms the vertical axis of the chart, distinct from the horizontal Ascendant-Descendant axis.
Practical use
The sign and planets close to the Midheaven describe how a person fulfills themselves publicly: career, social image, contribution to the world. A planet conjunct the MC powerfully marks vocation. Transits of Saturn, Uranus, Neptune or Pluto over the MC are often correlated with shifts in profession or status. On Tarotoui, the MC is calculated automatically from the natal data and appears on the chart map. The calculation requires a precise birth time: without that data, the MC remains undetermined, like the Ascendant.
Going further
The MC is not limited to career in the narrow sense: it describes the existential orientation of a life, which can be expressed outside of paid work. Note that in some rare house systems, such as Hellenistic Whole Sign, the MC can fall in a house other than the tenth. The majority of modern schools nevertheless keep it as the cusp of house X.