In astrology, a stellium is a specific astrological arrangement found in a chart. It is the name given to a group of planets, including the Sun and Moon, co-occurring in one section of an astrological chart, either by zodiac sign or house. It is a term used in all types of astrology charts, including transit charts and natal charts (birth charts). This article covers the conflicting definitions, the origin of the stellium in astrology, how rare it is, and describes what it means in a natal chart.

Unfortunately there is no consensus on the definition of “group of planets” when referring to the stellium. The most frequently used definition of a stellium is a group of 3 or more planets in a single sign or house.  However, the definition used by many astrologers is more precise and only includes 3 or more planets when they are also conjunct each other in a tight cluster or chain, typically within 10 degrees or less. Some astrologers prefer to use 4 or more planets, while others limit which planets can make up a stellium.

Some definitions exclude Mercury and Venus when found with the Sun, because those three are frequently found together due to their orbits, so their presence alone is not considered extraordinary, while others require the presence of a trans-personal planet (Jupiter, Saturn) or an outer planet (Uranus, Neptune, and Pluto) for it to be meaningful, for similar reasons. 

The History of Stellium in Astrology

My curiosity about the lack of consensus prompted me to research the topic. After spending a couple of hours searching through old translated manuscripts and more modern books on archive.org, it was apparent that very few authors had attempted to explicitly define what a stellium is. Most authors seem to assume the reader is already familiar with the concept and therefore only use the term to refer to astrology charts that include the configuration.

One of the first mentions of the word stellium was in 1951 by Margaret E Hone, in her book, The Modern Text Book of Astrology, she indicates stellium is the American word for the older British term: Satellitium. Centuries prior to this and for a decade or so after, satellitium was used to describe this special arrangement of planets.

The earliest mention of Satellitium I was able to find on archive.org was John Gadbury’s Astrological Almanac “Ephemerides of the celestial motions and aspects, eclipses of the luminaries for Year 1978” (see image below) in which he wrote:

“Now, to pre-occur the prodigious events, have we not had. (besides the 5 conjunctions of Saturn and Jupiter mentioned, etc.) a great conjunction of Saturn and Jupiter in Sagittarius, several great Eclipses of the Luminaries, and divers Conjunctions and oppositions of Sun, Saturn and Mars, a great Satellitium of all the Planets (almost) in Sagittarius in December 1675? together with fundry great Revolutions, Returns and Meetings of the Stars, and fundry Commers of late years: There is no Effect on Earth, but hath its Cause in Heaven.”

In another one of his books, The Astrological Sea-Man (1697), satellitium is mentioned, referring to a chart with an 8th house stellium where 5 planets are all conjunct (see image below).

Alan Leo, often referred to as the Godfather of Modern Astrology,  was the first astrologer to mention Satellitium in the context of zodiac signs in his book, The Art of Synthesis and How to Judge the Nativity (1912), but did not provide a full definition. It’s not until 1968 that stellium was defined in a dictionary written by Dal Lee.

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From Dictionary of Astrology by Dal Lee (1968):

SATELLITIUM, or Stellium—A collection of planets in one area of the zodiac. The term usually is used when referring to multiple’ conjunctions. A collection of five planets in one sign is an important satellitium; if the Sun is there also the significance is greater; still greater if the Moon should be there also. Sometimes four planets constitute a major satellitium, if they are major planets.

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This definition also supports the use of the word in an earlier book published in 1934: Some Principles of Horoscopic Delineation Book by Charles E. O. Carter.  which refers to groupings of 3 planets in conjunction.

I can only assume the common definition of 3 or more planets in one sign or house, often used today, is a simplified definition which could have accidentally left out the conjunction requirement that astrologers have been using since at least the 17th century, and likely since ancient times. Satellium is also used in a 1701 English translation of the Ancient Greek text by Claudius Ptolemy’s Quadripartite.

Is a stellium rare?

The answer depends on the definition. If going by the 3 or more planets in conjunction definition, it is not common, but also not rare. In the days before Uranus and the other outer planets were discovered, stelliums were rare, as there were only 7 astrological planets.

People born between 1955 and 1995 are more likely than other generations to have a stellium since 2 of the 3 outer planets (Neptune, Uranus, Pluto) were often in the same sign, requiring only one or two additional planets to complete the stellium.

A stellium of 4 planets is quite rare. A stellium of 5 or more planets are extremely rare, as are two stelliums in multiple signs or in multiple houses within the same chart.

What it means to have a stellium in your natal chart

The presence of a stellium in the natal chart brings extra attention to the sign or house it sits in. Depending on the strength of the stellium, it can very much dominate a chart in terms of personality traits for the zodiac sign or a house theme being significantly prominent in the person’s life. The native may feel like they strongly identify with the traits associated with the zodiac sign, possibly even more so than their Sun, Moon, or Rising sign. 

A stellium does not mean the house area of life will be easy for the native; it also doesn’t necessarily bring good luck or natural talents either. It often indicates a large portion of their energy will be focused on the area related to the house or sign throughout their life. It can indicate the native’s passions or a line of work they may feel most drawn to, but they can also bring complications, especially when malefic planets are involved. Having a stellium can bring about incredible growth and change in life circumstances, relationships, and career. 

The strength of a stellium 

The strength of a stellium is based on the number of planets involved, the larger the number, the stronger it is, in addition to the tightness of the clustering. Planets that are closer together by degrees (smaller degree difference between planets) are stronger and will have more impact on the chart and will form complex planetary pictures (patterns used in Uranian Astrology). When using quadrant house signs, including Placidus (the most commonly used house system), a stellium is also considered stronger when it’s both within the same house and sign. 

Weaker stelliums, such as those that consist of 3 planets, not in conjunction (i.e larger degrees between them), are less likely to dominate the chart in terms of zodiac traits or house themes.

A stellium’s impact on life events

Stelliums, especially ones where the planets are in conjunction, can bring about intense and even chaotic periods in life after a long time of relative calm. This happens when a slower moving planets transit or make contact with the stellium planets, hitting each planet one after the other. Like waiting for a bus for a long time, then multiple buses come along all at once, a chain of events happens in sequence in short succession. These chaotic periods are often full of change and can last a couple of years. Depending on the quality of the planets involved and their natal condition, it can be either a prosperous, rewarding time, a challenging time, or both. This is especially true for house-based stelliums, since so much focus is put onto one area of life.