Does Size Matter?

[Jim Eshelman]

What role does SIZE of a planet play in that planet's importance in astrology? It seems there must be some significance, but it would be useful to know what it is and how much. For example, we know it doesn't follow the rules of gravity, where an exponentially greater effect comes from greater mass and smaller distance.

Pluto, of course, is our poster child: Every time Pluto got measured over the years, it turned out to be smaller than we thought before. Yet, nearly every astrologer will say that Pluto has more powerful effect than most other planets in an equal situation. (Or, in the worst case, almost nobody thinks it is LESS important or impactful than the other planets.)

Possibly there is a size threshold - a cut off - but, if so, I don't know where it is. I can find viable results (more or less consistently) for the four largest asteroids and Chiron, but not at the level of planets: They "work," but not the same. Even when they deal with the same general themes as full planets, they don't seem to reduce to a fundamental, compelling need (root psychological pressure) like the full planets, e.g., Ceres vs. Moon for nurturing, or Vesta vs. Saturn for workaholism, or Chiron vs. Uranus for breakout freedom.

[Jim Eshelman]

Let's scale these a bit: The smallest thing astronomers currently call a planet is Mercury, which is 4,880 km in diameter. But at half that size, we know that astrologically Pluto is unequivocally effective: Pluto's diameter is 2,377 km.

The next most-sure thing IMO is Eris, and Eris is almost the same size as Pluto. Its diameter is 2,326 km.

To put this size in perspective: Our Moon (3,475 km) is larger - nearly the size of Mercury!

The next leap or gap, though, cuts this by more than half. Two solar system bodies are about the same size, and less than half the size of Pluto and Eris. These are Sedna (995 km) and Ceres (964 km). Interestingly, these are the next most confirmable bodies, though (so far) not nearly as much as Pluto and Eris. It's also intriguing to me how similar Pluto and Eris feel, and how similar themes are for Sedna and Ceres. (Not the same, but closer than most planets.) That raises an entirely other theoretical deep hole to mine: Do the planets astrological characteristics somehow emerge along some qualitative scale that is a function of their size?

We might (for example), be looking at a drop off between the size of larger than 2,000 km and smaller than 1,000 km, in round numbers.

Other factors that seem to have an effect in the scale of "I can see it, I can usually interpret it, but I can sure do without it" have the following sizes. Other than Chiron's proportionately outsized effect (does farther way mean more impactful?), these more or less follow the scale of how vividly they seem to perform (not that vivid applies to any of them):

Vesta - 573 km
Pallas - 568 km
Juno - 320 km
Chiron - 216 km

[Jim Eshelman]

Some of the observations above got me curious whether there is a qualitative relationship between a body's size and its meaning or temperament; i.e., are bodies of about the same size more likely to have similarities of meaning? To get eyes on it differently, here are the major and minor most likely astrologically valid bodies in our solar system ranked by relative diameter in kilometers (followed by the number of Earth diameters).

One (to me) ASTONISHING detail is that this scaling automatically groups non-luminary planets in the most familiar polarity sets: Jupiter-Saturn, Uranus-Neptune, Venus-Mars, and Mercury-Pluto. (How had I never seen this before?) the pairing is starkly evident in the size list. (What an interesting coincidence that, in each case, the benefic is a little larger than the malefic of the same pair.)

Sun 1,391,400 km - 109.20
Jupiter 139,822 km - 10.97
Saturn 116,464 km - 9.14
Uranus 50,724 km - 3.98
Neptune 49,244 km - 3.86
[Earth 12,742 km - 1.00]
Venus 12,104 km - 0.95
Mars 6,779 km - 0.53
Mercury 4,880 km - 0.38
Moon 3,475 km - 0.27
Pluto 2,377 km - 0.19
Eris 2,326 km - 0.18
Sedna 995 km - 0.08
Ceres 964 km - 0.08
Vesta 573 km - 0.04
Pallas 568 km - 0.04
Juno 320 km - 0.03
Chiron 216 km - 0.02

[mikestar13]

Reminiscent of my Astrology of Dwarf Planets thread. We've well established that Pluto is a full first rate planet, and therefor so is Eris. Perhaps there are classes of astrological planets? The break point between class 1 and class 2 would be somewhere between 1000 and 2000 km, or perhaps the dividing line is based on mass. Likewise, the very small (but still somewhat significant) stuff would be class 3, not sure where that dividing line should be. So class 1 would take in the standard ten planets plus Eris, class 2 would encompass Sedna, Ceres, Vesta, Juno, Pallas, Chiron and others in that size range. I'd expect when we read a nativity we will use class 1 planets, but when these seem to provide a dearth of information, we might look for prominent class 2 planets (immediate foreground, partile aspecta, etc.), very seldom would we look at class 3, but I can imagine cases where this might ha;pen. Might be worth experimenting with.

[Jim Eshelman]

Yes (just thinking aloud, of course, posing more questions than answers). The cutoffs might be in exponents of 10, e.g., below 2,000 km and below 200 km (and only occasionally worrying about a Temporary visitor below 20 km).

On an unrelated topic, I've been thinking of designating people who appear on the site briefly and then head out never (or rarely) returning Comets.

[mikestar13]

The 2,000km and 200km limits seem reasonable at this point. If there should prove to be situations where the class 2 planets have more say than usual, the numbers could be adjusted if experience dictates they should be. Perhaps study with the 11 class 1 bodies will refine formulas for the overall significance of a planet in a horoscope an a 0-100 scale based on angularity, aspects, rulership, stations, etc. then class 2 would have a lower maximum (67?, 50?) and a more frequent minimum.

[Jim Eshelman]

I want to redisplay the planet list in a way that makes more eye-poppingly visible how natural planet pairs are organized by the size difference. This one fact alone suggests to me that size is somehow connected to qualitative meanings of planets (since polar opposites are essentially alternative expressions of the same unifying idea). I was taken before more by, say, Sun's similarity to Jupiter and Moon's similarity to Mercury, so it didn't occur to me at first to drop out the luminaries. (As Pluto and Eris are very nearly PERFECT complements, this gives the alternative of thinking Moon-Mercury and Pluto-Eris rather than Mercury-Pluto... but I leave it as is for the moment.)

The tendency of Eris to sometimes seem to be Mercury-like in its trickster or data-coordinating function even shows. Whether this effect continues into what Mike reasonably dubbed "Class 2 bodies" is unclear, though some quiet recognitions stir.

More than 2,000 km
----------------------------- [Sun 1,391,400 km - 109.20]
Jupiter 139,822 km - 10.97
Saturn 116,464 km - 9.14
-----------------------------
Uranus 50,724 km - 3.98
Neptune 49,244 km - 3.86
----------------------------- [Earth 12,742 km - 1.00]
Venus 12,104 km - 0.95
Mars 6,779 km - 0.53
----------------------------- [Moon 3,475 km - 0.27]
Mercury 4,880 km - 0.38
Pluto 2,377 km - 0.19
Eris 2,326 km - 0.18

Less than 1,000 km
Sedna 995 km - 0.08
Ceres 964 km - 0.08
-----------------------------
Vesta 573 km - 0.04
Pallas 568 km - 0.04
-----------------------------
Juno 320 km - 0.03
Chiron 216 km - 0.02

[mikestar13]

The class 2 pairs are suggestive. One point I would raise WRT class 1: Mercury-Pluto-Eris seem to form a triad, and I'm not sure how Mercury fits, while Pluto-Eris seems to be a natural pair. Singling out from the collective vs. the collective itself (focusing on a single dimension). Perhaps what Me-Pl-Er have in common is that they are neutral, and malefic/benefic doesn't apply them. Benefic/malefic doesn't apply as neatly to Ur/Ne as to Ve/Ma and Ju/Sa but there is at least a tendency in that direction. If pressed, I might class Uranus as 2/3 benefic and 1/3 malefic. Change is IMHO favorable more often than not but by no means always. Neptune I would mark as 1/3 benefic and 2/3 malefic. Delusion is typically more harmful than fantasy is helpful.

[Jim Eshelman]

One point I would raise WRT class 1: Mercury-Pluto-Eris seem to form a triad, and I'm not sure how Mercury fits, while Pluto-Eris seems to be a natural pair.

Mercury-Pluto has long seemed a set of natural opposites (and treated by Bradley that way in Kid Gloves and statistical presentation of the 1950s), though I agree that Eris tosses in a wrench. Pluto (as the one singled out from the infinite set of nondimensional points) and Eris (the infinite set of nondimensional points) are exact compliments. Then again, Eris often seems like a steroid Mercury in the same way that Sedna seems like a steroid Venus. If we want to keep this all neatly schematic, though, the easiest way out is to pair Moon and Mercury - clear emotional-intellect opposites yet simultaneously so similar it's sometimes hard to distinguish them without pulling out the luminary card.

Perhaps what Me-Pl-Er have in common is that they are neutral, and malefic/benefic doesn't apply them.

True. (Though on the "malefic comes second in the pair" matter, notice how many astrologers try to insist Pluto is a malefic - and, in mundane astrology, the case is easier to make.)

[Jim Eshelman]

Mike suggested these might be based on mass instead of size. Probably these will be about the same, but I should check. Below, I will update the table replacing sizes with mass measurements as "Earth masses" or EMs.

I don't think this is the measurement. Nonetheless, if we were do draw a line, it would probably be at less than 0.001 (0.1%) of Earth's mass, which is half the mass of Pluto,

Sun - 332,950 EM
Jupiter - 317.8 EM
Saturn - 95.159 EM
Neptune - 17.147 EM
Uranus - 14.536 EM
[Earth - 1.0 EM (1.31668 x 10^25 kg)]
Venus - 0.815 EM
Mars - 0.107 EM
Mercury - 0.055 EM (3.3011 x 10^23 kg)
Moon - 0.0123 EM (7.342 x 10^22 kg)
Eris - 0.0027 EM
Pluto - 0.00218 EM
Ceres - 0.00016 EM
Sedna - unknown
Others - miniscule by comparison, sometimes unknown