What Is the Imum Coeli (IC) & The IC in the 12 Zodiac Signs

Q: How do you pronounce Imum Coeli?

Most English-speaking astrologers say IM-um SEE-lee . Reconstructed Latin is closer to EE-mum KAI-lee , and you will hear both. If you would rather not commit, “the IC” is what people actually say out loud.

4 min read·Updated Oct 27, 2026

What Is the Imum Coeli (IC)

In astrology, the Imum Coeli (IC), also known as the Nadir or Fourth House Cusp, marks the lowest point of the natal chart. It represents the foundation of one’s being: home, family, roots, and the private inner self. While the Midheaven (MC) points upward toward career and public life, the IC points inward and downward, symbolizing the personal world that lies beneath the surface. It governs:

The Imum Coeli (IC) axis highlighted on a natal chart wheel — The Imum Coeli — one of the four chart angles

Childhood environment and early family influences.
Ancestral heritage and cultural roots.
Inner emotional foundation and sense of security.
The home environment one creates later in life.

The IC reveals where a person feels most at home and safe, shaping their inner stability and the emotional soil from which they grow.

How to Find Your IC

The IC is not a planet you can look up — it is a point, the cusp of the fourth house, and it sits exactly opposite the Midheaven. That one fact gives you the whole method: find the MC, and the IC is the point 180° across the chart, at the bottom of the wheel. Because the MC–IC axis is tied to the local meridian, it is one of the fastest-moving things in a chart — the sky turns about 1° every four minutes, so an hour of error moves the axis roughly 15°. If your IC sits within a degree of a sign boundary, a birth time that is fifteen minutes off can change the sign. That is why IC work needs a recorded time, not a remembered one.

In practice:

Use the time on the birth certificate, not the time a relative remembers.
Enter the date, the exact time and the birth city into a birth chart calculator; it labels the IC at the bottom of the wheel.
Read the sign on the fourth-house cusp. In Placidus that cusp is the IC. In whole-sign houses there is no IC cusp, so the fourth-house sign and the IC sign can legitimately differ — worth knowing before you compare two readings.
No birth time? Treat the IC as provisional. Rectification can narrow it, but nothing recovers a time that was never recorded.

Imum Coeli Through the Signs

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The Imum Coeli (IC) in Pisces

FAQs

Is there an Imum Coeli calculator?

Yes — any birth chart calculator that draws houses marks the IC, because the IC is simply the fourth-house cusp, the point opposite the MC. Our free birth chart calculator labels it at the bottom of the wheel. You need the date, the exact birth time and the birthplace; without a time the IC cannot be placed.

How do you pronounce Imum Coeli?

Most English-speaking astrologers say IM-um SEE-lee. Reconstructed Latin is closer to EE-mum KAI-lee, and you will hear both. If you would rather not commit, “the IC” is what people actually say out loud.

Is the IC the same as the fourth house?

Not exactly. The IC is a point — the cusp of the fourth house, sitting opposite the MC. The fourth house is the whole 30° segment that follows it. In Placidus the two share a boundary, so the IC sign and the fourth-house sign come out the same; in whole-sign houses the fourth house begins at the sign boundary instead, and the two can differ by a sign. This is why two readings of the same chart sometimes disagree about the IC — check which house system the calculator used before assuming one of them is wrong.

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