What the IC Means in Astrology

A Midheaven at 8 degrees Leo puts the IC at 8 degrees Aquarius; with Scorpio rising in whole-sign houses that IC falls in the fourth house, but with Sagittarius rising it falls in the third.

The IC, short for Imum Coeli (Latin for the bottom of the sky), is one of the four angles of a birth chart. It is the point on the zodiac directly opposite the Midheaven, which is the highest point of the chart. Picture the sky as a dome over your birthplace: the Midheaven is where the zodiac crosses the north-south line overhead, and the IC is where the zodiac crosses that same line beneath your feet.

It is not a planet or a star. It is a calculated degree of a sign, a point with no body behind it. In the tradition it stands for the foundation of the chart: home, family background, private life and the inner place a person returns to when nobody is watching. On the wheel it sits at the bottom, so a common picture is the roots beneath a tree.

Because the point depends on the exact time of birth, you cannot find an IC without one. If the time is a guess, the IC is a guess too.

Chart software finds the Midheaven from the birth time and the longitude of the birthplace, then places the IC exactly 180 degrees away. As a shortcut, the IC is always the opposite sign at the same degree: a Midheaven at 8 degrees of Leo gives an IC at 8 degrees of Aquarius. To check the arithmetic, treat the zodiac as a number line from 0 to 360.

1. Write the Midheaven as a number. Aries starts at 0, Taurus at 30, Gemini at 60 and so on, so 8 degrees of Leo is 120 plus 8, or 128.
2. Add 180. Here 128 plus 180 is 308.
3. If the total is above 360, subtract 360. A Midheaven at 20 degrees of Scorpio is 230, and 230 plus 180 is 410, which becomes 50.
4. Turn the number back into a sign by dividing by 30. The 308 is ten full signs (300) and 8 degrees, so it is 8 degrees of the eleventh sign, Aquarius. The 50 is one full sign and 20 degrees, so it is 20 degrees of Taurus.

In Placidus and other quadrant house systems, the IC is the cusp of the fourth house, the exact degree where that house begins. In whole-sign houses the fourth house is simply the sign three places after the Rising sign, and the IC is a degree that may or may not land inside it. At most birthplaces it falls in the third, fourth or fifth house, and at very high latitudes it can reach a neighboring one.

Take a constructed IC of 8 degrees Aquarius. With Scorpio rising, whole-sign houses make Aquarius the fourth house, so the IC sits in it. With Sagittarius rising, the fourth house is Pisces, and the same IC falls in the third house. The point has not moved; only the house boundaries have.

Neither reading is a mistake. Choose one house system and say which. The IC’s sign, its ruler and any planets close to it stay the same in every system.

The sign on the IC colors the style of your private base. The table gives the traditional theme for each sign and a question you can ask yourself. They are prompts for thought, not statements about your upbringing.

A planet within about 5 degrees of the IC, on either side, is said to be conjunct it. Some astrologers allow up to 8 degrees; there is no official limit. Traditionally such a planet is emphasized because it sits at a corner of the chart, and it is read as strongly tied to home and inner life.

• Sun: a sense of identity bound up with family, place or heritage.
• Moon: a strong need for a safe, familiar base, with moods that may follow the state of the home.
• Venus: a need for beauty, calm and affection in the living space.
• Mars: a need for room to move and act at home; the tradition also links it with a busy or lively household, a theme to consider rather than a fact about your family.
• Saturn: an early sense of duty or seriousness around home, and a slow, careful approach to building a base.
• Uranus, Neptune or Pluto: an unconventional, diffuse or intense home theme. The planet's sign is shared by everyone born in those years, so it is the contact with your own IC that makes the theme personal.

This takes about twenty minutes and needs only paper. It is a journaling prompt, not an assessment of your family.

1. Write down the sign on your IC, its ruling planet, and the house system you used.
2. Without looking at the table, list three words for the home you grew up in and three words for the home you would like now.
3. Read the table row for your IC sign. Mark every phrase that fits and every one that does not.
4. If a planet sits near the IC, add one sentence about what that planet’s job is in your life.
5. Look at where your two lists differ, and ask which differences come from choice and which from circumstance.
6. Keep the page and reread it in a few months.

First, the IC is not the same as the fourth house: one is a point, the other an area of the chart. Second, it is not the Moon, though the two share themes of home and belonging. Third, astrologers disagree about whether the IC and fourth house describe the mother, the father or both. Modern writers more often read the whole early home. Treat the IC as a question about what home means to you now, not as history.

The IC is a question about what home means to you now, and it cannot reveal facts about your childhood, mother or father.