What do ASC, DSC, MC and IC lines mean? The four angles in astrocartography
Every planet has four lines in astrocartography: Ascendant (AC/ASC), Descendant (DC/DSC), Midheaven (MC) and Imum Coeli (IC). What each one means.
In astrocartography every planet has four lines, each showing where that planet stood on one of the four key points of the sky at your birth. On the AC (ASC) line the planet was rising in the east, on the DC (DSC) line it was setting in the west, on the MC line it was at the top of the sky, and on the IC line it was directly beneath your feet. In a birth chart these four points are called the "angles" and are considered the most powerful positions.
In short: AC = you, DC = your relationships, MC = your career, IC = your home.
The AC (ASC, Ascendant) line: yourself
The AC line marks where the planet was rising over the eastern horizon at your birth. It is the same point as the rising sign in your birth chart. Here the planet's energy flows straight into you: your personality, your body and how others see you. AC lines are the most "personal" lines; there you feel like that planet.
Example: on a Venus AC line you may feel more attractive and sociable, on a Mars AC line more energetic but also more impatient.
The DC (DSC, Descendant) line: relationships
The DC line marks where the planet was setting on the western horizon, exactly opposite the AC. In the birth chart it is the cusp of the 7th house. On this line the planet's theme is lived less through you and more through the people you meet: lovers, spouses, business partners and even rivals.
Example: Venus DC is a classic line for love; a Saturn DC line can bring serious, committed but tested relationships.
The MC (Midheaven) line: career and reputation
The MC (Medium Coeli, "middle of the sky") line marks where the planet was at its highest point in the sky at your birth. On the map it is a straight line of longitude from north to south. The MC describes your career, your public standing, your reputation and your goals. On this line the planet works in a place everyone can see.
Example: Jupiter MC is one of the best-known lines for career luck and promotion; Sun MC brings visibility and leadership.
The IC (Imum Coeli) line: home, family and roots
The IC (Imum Coeli, "bottom of the sky") line marks where the planet was directly underfoot, on the other side of the Earth. It is exactly opposite the MC and is also a straight line of longitude. The IC describes home life, family, roots and your inner world. On this line the planet is felt in your private life.
Example: Moon IC gives a deep sense of home; Uranus IC can bring frequent moves and a changeable home life.
Why are MC and IC straight and AC and DC curved?
Because the Earth spins on its axis, the moment a planet crosses the top of the sky happens at the same longitude for every latitude, so MC and IC are straight lines. The point where a planet touches the horizon depends on latitude: rising and setting times shift as you go north or south. That is why AC and DC lines curve and sometimes do not form at all near the poles.
Which angle is the strongest?
Traditionally all four angles count as strong, but they show up in different areas. Most astrologers read MC and AC lines as the most noticeable, IC as more inward and slower to register, and DC as an influence that arrives through other people. For all of them, distance matters: strong up to 300 km, moderate up to 600 km, weak up to 800 km.
See it on your map
Astrokarto draws the four lines of each planet in different line styles, and clicking a line lists the major cities along it. Create your map, or first read How to read your map.