Redefining Mercury’s Apparent Ecliptic Speed

Redefining Mercury’s Apparent Ecliptic Speed Using 200 Years of Empirical Astronomical Data (1900–2100)

Author

MINAKAWA Takeshi
Astrogrammar Research, Charapla Inc,
Yokohama, Japan
November 17th, 2025
[日本語版]

Abstract

Traditional astrological classifications of Mercury’s apparent daily speed—Slow, Average, and Fast—have historically been determined by conventional intuition rather than empirical astronomy. This study calculates 73,213 days of Mercury’s geocentric apparent ecliptic longitude speed from 1900 to 2100 using the JPL DE440s ephemeris and the Skyfield computation library. The resulting distribution reveals statistically robust boundaries based on quartiles and physically meaningful structures related to Mercury’s orbital dynamics. We propose a new five-tier classification—Ultra-slow, Slow, Average, Fast, Very-fast—which integrates statistical percentiles and dynamical constraints near retrograde stations. This framework represents fully empirical and reproducible standard for Mercury’s speed in both astronomical and astrological contexts.


1. Introduction

In both astronomy and astrology, the apparent motion of Mercury exhibits distinctive behavior due to its small orbital radius, high eccentricity (e ≈ 0.2056), and rapid synodic cycle. Astrological practice traditionally divides Mercury’s speed into “Slow,” “Average,” and “Fast,” but these categories lack empirical grounding and vary between authors.

This study aims to:

  1. Compute Mercury’s daily apparent ecliptic longitude speed for 1900–2100.
  2. Analyze its distribution using modern statistical techniques.
  3. Identify natural physical structures such as stationary regions.
  4. Establish an objective, reproducible classification system that unifies
    astronomy, statistics, and astrological interpretation.

This work presents the most extensive numerical analysis of Mercury’s daily apparent speed to date.


2. Methods

2.1 Ephemeris and Computational Tools

  • Ephemeris: JPL DE440s (downloaded binary kernel)
  • Library: Skyfield 1.53
  • Reference frame: geocentric → ecliptic_frame
  • Sampling: one data point per day at 00:00 UT
  • Period: 1900-01-01 to 2100-12-31
  • Total days: 73,213

2.2 Calculation of Apparent Ecliptic Longitude

For each date ( t ), Mercury’s geocentric apparent position is computed as:

Daily apparent speed is approximated by a first-order difference:

v(t)=λ(t)−λ(t−1)

2.3 Unwrapping Logic

Because longitude is cyclic (0–360°), discontinuities are resolved by:

  • If Δλ > 300°, subtract 360°
  • If Δλ < −300°, add 360°

This ensures continuity near 0°/360°.

2.4 Statistical Processing

We compute:

  • Percentiles: p10, p25, median, p75, p90, p95
  • Distribution histograms
  • CDF curves
  • Extreme-value regions (near-zero, near-max speed)

Figures were generated using matplotlib.


3. Results

3.1 Distribution Characteristics

Across 73,213 data points:

Statistic Speed (°/day)
p25 0.373
Median 1.352
p75 1.657
p90 1.927
p95 2.054

Key observations:

  • The central distribution is sharply peaked around 1.3–1.4°/day.
  • Speeds below 0.40°/day belong to a statistically distinct minority (~25%).
  • Speeds above 1.65°/day form the natural “fast tail” (~25%+).
  • Speeds above 2.0°/day are rare (~5%).

3.2 Figures

Figure 1. Histogram of Mercury’s daily ecliptic speed (1900–2100).

Figure 2. Cumulative distribution function (CDF).

3.3 Physical Behavior Near Retrograde Stations

Close to Mercury’s retrograde station:

  • True derivative dλ/dt approaches ≪ 0.01°/day
  • Daily differencing inflates this to ≈ 0.05°/day
  • Station-proximate days cluster at |v| < 0.20°/day

This indicates a “dynamical basin” distinct from the general slow region.


4. Discussion

4.1 Statistical Justification for Category Boundaries

The quartile structure naturally divides speed states:

  • Slow: below p25 (0.373°/day → rounded to 0.40)
  • Average: p25 to p75 (0.40–1.65)
  • Fast: above p75 (1.65+)

These are non-arbitrary, arising from real data.

4.2 Dynamical Justification

Physical considerations require an additional category:

  • Near station, dλ/dt ≈ 0
  • Motion is qualitatively different from “ordinary slowness”

This motivates the Ultra-slow category.

4.3 Proposed Final Classification

Category Speed (°/day) Basis
Ultra-slow |v| < 0.20 Station-proximate basin
Slow 0.20–0.40 p25 alignment
Average 0.40–1.65 p25–p75
Fast 1.65–2.0 accelerated tail
Very-fast >2.0 extreme tail

This unifies observational astronomy and astrological semantics.


5. Conclusion

This study proposes empirically validated, physically meaningful
classification of Mercury’s daily apparent speed.

Key achievements:

  • Created a reproducible 73,213-point dataset
  • Identified statistically robust boundaries
  • Discovered a distinct near-station dynamical region
  • Proposed a modern 5-category speed model

The results provide a foundation for future work in both astronomical modeling
and high-precision astrological techniques.


6. References


Appendix A. Source Code


from skyfield.api import load
from skyfield.framelib import ecliptic_frame
from datetime import date, timedelta
import csv

ts = load.timescale()
eph = load('de440s.bsp')

earth = eph['earth']
mercury = eph['mercury']

def mercury_lon(t):
    ast = earth.at(t).observe(mercury)
    lat, lon, dist = ast.frame_latlon(ecliptic_frame)
    return lon.degrees

start_year = 1900
end_year = 2100

output_file = "mercury_velocity_1900_2100.csv"

with open(output_file, "w", newline="") as f:
    writer = csv.writer(f)
    writer.writerow(["date", "velocity_deg_per_day"])

    for y in range(start_year, end_year + 1):
        d = date(y, 1, 1)
        end = date(y, 12, 31)

        t_prev = ts.utc(d.year, d.month, d.day)
        prev_lon = mercury_lon(t_prev)
        d += timedelta(days=1)

        while d <= end: t = ts.utc(d.year, d.month, d.day) lon = mercury_lon(t) diff = lon - prev_lon if diff > 300:
                diff -= 360
            elif diff < -300:
                diff += 360

            writer.writerow([d.isoformat(), diff])

            prev_lon = lon
            d += timedelta(days=1)

print("DONE")

──────────────────────────────────

Appendix B. Mercury Daily Speed Dataset (1900–2100)

File name: mercury_velocity_1900_2100.csv
Format: UTF-8 (comma-separated)
Total Rows: 73,213
Columns:

Column Description
date ISO 8601 date (YYYY-MM-DD)
velocity_deg_per_day Daily apparent ecliptic longitude speed (degrees/day)

The full dataset is provided as a downloadable supplemental file:

Download:
mercury_velocity_1900_2100.csv


B.1 Sample: First 10 Rows of the Dataset

date,velocity_deg_per_day
1900-01-02,1.254…
1900-01-03,1.287…
1900-01-04,1.315…
1900-01-05,1.347…
1900-01-06,1.372…
1900-01-07,1.394…
1900-01-08,1.412…
1900-01-09,1.427…
1900-01-10,1.438…
1900-01-11,1.447…

(Values truncated for brevity. Full precision available in the downloadable CSV.)


B.2 Reproducibility

The entire dataset can be reproduced using the Python script provided in Appendix Aand the JPL DE440s ephemeris file.

──────────────────────────────

Supplement: Relationship Between Retrograde Motion and Speed Classification

The five-tier speed model proposed in this study—Ultra-slow, Slow, Average, Fast, Very-fast—represents the magnitude of motion (kinematic intensity) measured as the absolute value of apparent daily longitude speed |v|.
It is independent from the retrograde state, which describes only the direction of motion.

During computation, Mercury’s apparent daily speed v(t) includes its mathematical sign
(positive for direct, negative for retrograde).
However, when defining categories, we intentionally use |v| in order to isolate the meaning of movement strength, without mixing it with directional symbolism.

1. Speed and Retrograde Are Separate Axes

Speed is a continuous variable, while retrograde is a binary state (on/off).
Handling them separately provides a clearer and more structured interpretation framework.

Concept Speed Classification Retrograde Status
What it represents Strength / intensity of motion Direction (forward/backward)
Data type Continuous Discrete (True/False)
Value used v

2. A Common Misconception

It is often assumed that retrograde automatically means slow, but the data show:

  • Mercury becomes extremely fast just before entering retrograde
  • Significant fast retrograde segments exist
  • Stationary periods are not equivalent to ordinary slowness, but form a distinct basin where |v| approaches zero

Therefore, conflating slowness with retrograde is a conceptual error.

3. Symbolic Interpretation Matrix

Practical astrological meaning emerges more clearly when speed and direction are crossed as two independent axes:

Speed × Direction Indicative Symbolism (Horary Astrology Interpretation)
Ultra-slow × Direct Stillness before emergence; concentration; threshold before action
Ultra-slow × Retrograde Turning point; maximum reconsideration; boundary of reversal
Fast × Direct Acceleration; execution; peak agency
Fast × Retrograde Rapid restructuring; intense internal processing
Very-fast × Direct Breakthroughs; rapid development
Very-fast × Retrograde Explosive return of past matters; dramatic review

4. The Role of Station (Near-Stillness)

Near Mercury’s stationary points, |v| drops below 0.20°/day, defining a qualitatively distinct regime.
This region is not simply low speed, but a dynamic inversion zone, marking transitions between phases.

───────────────────────────────────────

1900〜2100 年の天文データに基づく「水星の視黄経速度」再定義研究

著者

皆川剛志
Astrogrammar Research, Charapla Inc.
横浜市、日本
November 17th, 2025

要旨(Abstract)

占星術で伝統的に用いられてきた “水星の速度分類(Slow / Average / Fast)” は、歴史的慣習に基づくものである。本研究では、1900〜2100 年の 73,213 日分にわたり、水星の地心視黄経の日次変化量(°/day)を、JPL DE440s の高精度天体暦および Skyfield 計算ライブラリを用いて算出した。得られた速度分布は、四分位点および水星の軌道力学構造(留付近の準停滞)と明確に一致し、従来の分類よりも科学的に整合的な境界値が得られた。

本研究は、統計的および物理的根拠に基づく 5 区分類(Ultra-slow / Slow / Average / Fast / Very-fast) を提案し、占星術における水星速度の標準化に新たな基盤を提供する。


1. 序論(Introduction)

水星は太陽に最も近い惑星であり、

  • 軌道離心率が高い(e ≈ 0.2056)
  • 公転速度が速い
  • 地球から見た視運動が複雑

といった特徴を持つ。そのため視黄経速度は大きく変動し、特に逆行前後には明瞭な「留」の現象を示す。

しかし、占星術で一般的に使用される「Slow」「Fast」の基準は、統計的根拠・物理的根拠ともに欠如しており、著者や時代によって基準が異なる。

本研究の目的は:

  1. 水星の視黄経速度を 1900〜2100 年の全日について算出する
  2. 速度分布の統計的構造(四分位点、極値)を精査する
  3. 留付近の物理的速度構造(Stationary basin)を抽出する
  4. 統計+物理+占星術の三領域を統合した客観的分類を提案する

本研究は、これまでにない規模と精度で水星の速度分布を扱う初の試みである。


2. 手法(Methods)

2.1 天体暦と計算ツール

  • 天体暦: JPL DE440s
  • 計算ライブラリ: Skyfield 1.53
  • 座標系: 地心視位置 → 黄道座標(ecliptic_frame)
  • 計算時刻: 毎日 00:00 UT
  • 対象期間: 1900-01-01〜2100-12-31
  • データ数: 73,213 日

2.2 視黄経の算出

水星の視黄経 λ(t) を求め、日次差分として速度を近似する:
v(t)=λ(t)−λ(t−1)

2.3 ラップ補正

黄経は 0°〜360° の循環量であるため、以下を適用:

  • Δλ > 300° → Δλ − 360
  • Δλ < −300° → Δλ + 360

跳躍を回避し、連続的な速度値を得る。

2.4 統計処理

以下を算出:

  • 四分位点(p10, p25, median, p75, p90, p95)
  • 速度ヒストグラム
  • 累積分布関数(CDF)
  • 留付近の極小速度域(|v| < 0.20)

図版生成には matplotlib を使用した。


3. 結果(Results)

3.1 速度分布の統計構造

統計量 値(°/day)
p25 0.373
median 1.352
p75 1.657
p90 1.927
p95 2.054

主要結果:

  • 中央付近は 1.3〜1.4°/day に密集
  • 0.40°/day 以下は全体の約 25% に相当し、自然な低速帯を形成
  • 1.65°/day 以上は高速帯
  • 2.0°/day を超える値はごく稀(約 5%)

3.2 図版

図1. 水星の視黄経速度ヒストグラム(1900–2100)

 

図2. 水星速度の累積分布(CDF)

3.3 留付近の物理的挙動

逆行前後の留付近では、

  • 真の速度(導関数) dλ/dt は ±0.0005°/day 程度
  • 日次差分速度は ±0.05°/day 程度に「丸め」られる

そのため |v| < 0.20°/day の領域は、一般的な Slow 領域とは
質的に異なる「準停滞域(station-like basin)」である。


4. 議論(Discussion)

4.1 統計に基づく境界値の妥当性

速度分布の四分位点は、自然な境界を与える:

  • Slow 上限:p25 ≈ 0.373(0.40 に丸め)
  • Average:p25〜p75
  • Fast 下限:p75 ≈ 1.657(1.65)

これらは全て 恣意性がなく、データに基づく境界である。

4.2 軌道力学に基づく Ultra-slow の必要性

水星の留付近での準停滞は、通常の低速帯とは明らかに異なる挙動を示す。

  • 動きがほぼ停止
  • 速度符号が反転する
  • 軌道の2階微分が小さくなる

そのため Ultra-slow(|v| < 0.20) を別区分とすることは理論的に整合的。

4.3 最終的な速度分類の提案

区分 速度(°/day) 根拠
Ultra-slow |v| < 0.20 留・逆行転位点周辺の準停滞として物理的現象に基づく
Slow 0.20–0.40 p25 を基準
Average 0.40–1.65 p25〜p75
Fast 1.65–2.0 高速帯
Very-fast >2.0 極端高速帯

これは、統計・物理・占星術の三立場を同時に満たす最良の分類である。
※ |v| は地心視黄経速度 v の絶対値を示す。


5. 結論(Conclusion)

本研究は水星の視黄経速度を実データに基づき厳密に再定義した。

成果として:

  • 73,213 日分の速度データを作成
  • 統計的に自然な速度境界を決定
  • 留近傍の準停滞域を特定
  • 5 区分モデル(Ultra-slow〜Very-fast)を提案

この結果は、今後の占星術技法(特に予測占星術・時期判断)において新しい標準として機能し得る。


6. 参考文献(References)


付録 A. Python ソースコード


from skyfield.api import load
from skyfield.framelib import ecliptic_frame
from datetime import date, timedelta
import csv

ts = load.timescale()
eph = load('de440s.bsp')

earth = eph['earth']
mercury = eph['mercury']

def mercury_lon(t):
    ast = earth.at(t).observe(mercury)
    lat, lon, dist = ast.frame_latlon(ecliptic_frame)
    return lon.degrees

start_year = 1900
end_year = 2100

output_file = "mercury_velocity_1900_2100.csv"

with open(output_file, "w", newline="") as f:
    writer = csv.writer(f)
    writer.writerow(["date", "velocity_deg_per_day"])

    for y in range(start_year, end_year + 1):
        d = date(y, 1, 1)
        end = date(y, 12, 31)

        t_prev = ts.utc(d.year, d.month, d.day)
        prev_lon = mercury_lon(t_prev)
        d += timedelta(days=1)

        while d <= end: t = ts.utc(d.year, d.month, d.day) lon = mercury_lon(t) diff = lon - prev_lon if diff > 300:
                diff -= 360
            elif diff < -300:
                diff += 360

            writer.writerow([d.isoformat(), diff])

            prev_lon = lon
            d += timedelta(days=1)

print("DONE")

───────────────────────────────────────

付録B. 水星視黄経速度データセット(1900–2100)

ファイル名: mercury_velocity_1900_2100.csv
形式: UTF-8(カンマ区切り)
総行数: 73,213 行
カラム仕様:

カラム名 内容
date ISO 8601形式の日付(YYYY-MM-DD)
velocity_deg_per_day 視黄経の日次変化量(°/day)

完全版データは以下よりダウンロード可能:

ダウンロード:
mercury_velocity_1900_2100.csv


B.1 データ冒頭10行(サンプル)

date,velocity_deg_per_day
1900-01-02,1.254…
1900-01-03,1.287…
1900-01-04,1.315…
1900-01-05,1.347…
1900-01-06,1.372…
1900-01-07,1.394…
1900-01-08,1.412…
1900-01-09,1.427…
1900-01-10,1.438…
1900-01-11,1.447…

(※表示のため一部数値を簡略化。完全精度はCSV本体に収録)


B.2 再現性について

本データセットは、付録AのPythonコードとJPL DE440s 天体暦ファイルを用いることで完全に再現可能である。

──────────────────────────────────

補則:逆行と速度分類の関係について

本研究で提案した 水星の速度分類(Ultra-slow / Slow / Average / Fast / Very-fast) は、運動量(変化量の大きさ)を示す軸であり、順行・逆行といった運動方向の区分とは独立の概念 である。

計算段階では、視黄経速度 v(t) は実際の変化量として **符号付き(正=順行、負=逆行)**で算出されるが、
速度分類においては |v|(絶対値)を用いる
これは、占星術的に「動きの勢い」としての意味内容を抽出するためであり、順行・逆行の方向性に依存しない 純粋な運動の強度 を表現する。

1. 速度分類と逆行は異なる概念軸

速度分類は連続値を区切る分類であり、逆行は on/off の離散値 である。
これらは 2軸として扱う ことで現象の理解が立体的になる。

概念 速度分類 逆行ステータス
何を表すか 動きの強さ(勢い) 動きの向き(方向)
データ型 連続 離散(True/False)
使用値 v

2. 誤解しやすい点

一般には「逆行=遅い」と思われがちだが、実際には、

  • 逆行開始直前の順行期は最速域に達する
  • 逆行中にも高速逆行は存在する
  • 留付近は Ultra-slow(物理的に停滞)

つまり、「速度の弱さ」と「逆行状態」を同一視するのは誤りである。

3. 速度分類 × 順行/逆行 の象徴的組み合わせ

以下は占星術的利用のための象徴整理である:

速度分類 × 順行/逆行 象徴的解釈例(ホラリー占星術)
Ultra-slow × Direct(順行) 新しい展開の直前、意志の収束、静止点
Ultra-slow × Retrograde(逆行) 転換点、再検討の極大、方向反転の閾値
Fast × Direct 外向的な加速、行動力の頂点
Fast × Retrograde 再構築の急進、内面化された推進力
Very-fast × Direct 事象の急展開、突破
Very-fast × Retrograde 過去の事象の爆発的再浮上、激しい再評価

4. Station(留)の位置づけ

留前後では |v| が極端に小さくなり、Ultra-slow に分類される
この現象は速度の継続的変動から切り離された 質的転位点 として扱うことができる。

───────────────────────────

Astrological Conditions for Success

Astrological Conditions for Success: Saturn and Mars

Twenty-five years ago, I was asked about the astrological conditions for success. I remember explaining it at the time in terms of “Jupiter is…” or “Venus is…”. If I were asked the same question today, I would answer this way.

The first condition for success is “to fail.” The second is “to not quit.” The third is “to decide for yourself what success means.”

These may sound different from the glittering laws of success. They might even suggest a gritty, unglamorous path. But as we overlap the astrological planets with our own lives, these three conditions should become clearer.

Contents The Effectiveness of Failure The Passion That Supports “Not Quitting” You Define Success Getting Lost on Your Own Path with Someone Else’s Map Strategic Use of Natural Significators Failure as Normal Operation — The Work of Saturn and Mars The Two Pillars Supporting Continuation — Saturn’s Patience and the Sun’s Will Defining Your Own Success — A Team Effort Philosophy and Operation, and “When Things Just Won’t Work” Practical Work for Using the Stars as a Compass

Show All The Effectiveness of Failure Why is failure a condition? Because there is so much we can only learn from failure. When things are going smoothly, we do not deeply reflect on the mechanics or assumptions. But when we hit a wall, when our plans are thwarted, and when we acknowledge defeat, we stop for the first time and begin to search for the root cause. Only this process can turn experience into true strength and sublimate it into unwavering skill.

In astrology, this learning through “failure” or “defeat” is symbolized by the work of Saturn. Saturn gives us limitations, difficulties, and challenges that must be tackled over time. The pressure is never pleasant, but by confronting the propositions Saturn gives us, a solid foundation and an essential understanding await. It is, so to speak, the process of forming the skeleton of one’s life.

The Passion That Supports “Not Quitting” The second condition, “to not quit,” is not about sheer guts. Its essence lies in continuing to follow the passion that wells up from within, the preferences one is drawn to—in other words, the soul’s desire. Even if it seems wasteful or meaningless to others, you can continue walking without hesitation on a path that your own heart strongly desires.

Astrological interpretation considers this inexhaustible energy to be the domain of Mars. Mars rules the fighting spirit and motivation. Without this active force, we cannot even take the first step. Of course, Mars’s energy can sometimes lead to conflict with others or difficult situations. However, without that powerful energy to carve a path, achieving anything is impossible.

You Define Success And the most important is the third condition: “to decide for yourself what success means.” We are unconsciously influenced by images of success created by society and others. But is that goal truly what you desire? As long as you chase values created by others, you will never achieve heartfelt conviction and satisfaction, even if you obtain them.

Setting your own goal. This is nothing less than an act of creating your own universe, leaving the gravity of others’ approval. Mars and Saturn are deeply involved in this process of “decision.” Since ancient times, Mars has symbolized separation. The decisiveness to follow one’s own will without being swayed by others is the power of Mars. A “decision” (ketsudan) is nothing less than “cutting off” (tatsu) other options. Saturn symbolizes building your own rules and structure based on that decision and continuing to protect it.

Getting Lost on Your Own Path with Someone Else’s Map The importance of “deciding your own success” also emerges from examples like this. Imagine you are smoothly progressing on a career path you admired, acquiring “conventional success” such as social status and income. You are congratulated by those around you, and you yourself feel a temporary sense of accomplishment. However, after a while, a feeling of an empty hole in your heart and a vague question—”Is this what I really wanted to do?”—emerges.

That is a sign that you are realizing the image of success you were chasing was one created by your parents, society, or the media, and not what you truly desired.

If you proceed unaware on a success map that is not your own, it is inevitable that you will get lost along the way. You lose sight of where you are and what you are doing it for. Passion is lost, daily efforts become mere obligations, and the goal that once seemed to shine brightly fades.

This “sense of dissonance” is the catalyst for “separation” brought by Mars. It is the moment you separate others’ values from your own true desires and decide, “This is not my path.” Only after this potentially painful decision can we enter the Saturnian creative process of building our own definition of success.

Now, these elements of “failure,” “continuation,” and “decision.” These differ from the brilliant symbolism of Jupiter (expansion, development) and Venus (joy, harmony), which are generally considered fortunate stars.

Learning within limitations (Saturn), continuing with passion (Mars), and establishing one’s own goals (Mars/Saturn). One’s own success is built by the work symbolized by Mars and Saturn.

Of course, there are times when things do not go well even if you try. When the wind is against you, anything you do just spins your wheels. There is no need to go for a walk when a typhoon is coming. At such times, just go ahead and blame it all on Mars and Saturn. This is not abandoning responsibility, but rather the wisdom to accept the flow of things beyond your control, to avoid blaming yourself needlessly, and to move toward the next step.

I also discuss the importance of the malefic stars in my own book, “Complete Master Predictive Astrology: From Basics to Practice.”

Strategic Use of Natural Significators In astrology, there are concepts of functional significators and natural significators. A typical example of the former is the house ruler, which differs depending on the birth chart. For example, if the 1st house is in Cancer, the “Moon” is the planet that universally represents that person’s spirit, personality, body type, and constitution. On the other hand, a natural significator refers to the things or concepts that each planet innately symbolizes: the Sun for ambition and will, the Moon for body and mind, Mercury for intellect and words, and so on. From here, I will talk about the aspect of natal planets as natural significators.

Failure as Normal Operation — The Work of Saturn and Mars In the first half, I listed “failure,” “continuation,” and “self-determination” as conditions for success and touched on the work of Mars and Saturn behind them. From here, let’s explore more deeply the mechanism of how these planets are specifically involved in our growth.

First, about “failure.” We tend to see failure as something to be avoided, a negative event. Japan is a cautious and careful culture with a strong aversion to failure and mistakes. However, from an astrological perspective, failure is nothing other than the “normal operation” brought about by Saturn and Mars.

Saturn is the planet that teaches us our limits and makes us recognize reality. Its work often manifests as delays or losses, mercilessly exposing the holes and optimistic outlooks hidden in our plans. This is the role of a “teacher who draws boundaries.” What is the acceptable range, and what is overstepping? Through harsh judgment, it conveys the rules of reality to us. Mars governs haste and severance, bringing friction during the trial-and-error process. It sometimes destroys things with impulsive actions and causes painful experiences, but that itself is the learning process. Mars can be said to be like a “surgeon who cuts away waste,” separating unnecessary parts and leaving only the essence. In other words, failure is healthy proof that these two planets are fulfilling their respective roles. When viewed from this perspective, the malefic stars are not heels (villains) who torment us. And there is something important here.

That point is that to use this teacher and surgeon effectively, we must give them specific “jobs.” In the planning stage, give Saturn a clear framework (standards, deadlines, specifications, quality control). And give Mars concrete tasks in advance, such as the number of experiments (number of prototypes, number of tests). By doing so, their energy is guided in a constructive direction, and failure is sublimated from a mere loss into valuable, pre-planned data.

The Two Pillars Supporting Continuation — Saturn’s Patience and the Sun’s Will This line marks the end of the free display area. Next is “not quitting,” or continuation. This is also Saturn’s domain. Patience, repetition, and daily accumulation. The ability to steadily perform tedious work is the true strength of Saturn.

However, it is not good to just continue blindly. The Sun plays the important role of determining the central axis of what should be continued. The Sun symbolizes our central sense of purpose, consistency, and leadership in our own lives.

Continuation is supported by the two pillars of Saturn’s “repetitive power” and the Sun’s “sense of purpose.” The Sun declares, “I will climb this mountain,” and Saturn creates the execution plan, “Then let’s advance one hundred steps every day.” Only with this collaboration does continuation become a meaningful force.

Habits to effectively operate these two planets include, for example:

Monthly Saturn Ritual: At a fixed time, such as the beginning of the month, perform “fixed-point observation” to reflect on the previous month’s progress and “take inventory” of tasks. Calmly check reality: Is it progressing according to plan? Are there obstacles? Annual Sun Review: At the end of the year, broaden your perspective slightly and reconfirm whether the direction you are heading is correct in the first place, and whether you have strayed from the path you desire. This is an important process to avoid getting buried in immediate tasks and losing sight of the larger goal. Defining Your Own Success — A Team Effort And the most important, “deciding for yourself what success means.” This is the work of creating your own compass and requires team play by multiple planets.

First, the team leader is the Sun. The Sun raises the purpose, the final vision (what the ancient Greeks called “Telos/purpose”), of “how one ultimately wants to be.” Supporting that purpose is Jupiter. Jupiter defines the meaning and philosophy of that success and provides an attractive “narrative” of “why aim for it.” Venus is in charge of the joy and values in the process. It designs rewards such as comfort, beauty, and connection with people, increasing sustainability (fuel efficiency) for continuing the journey. Finally, Mercury verbalizes that definition and breaks it down into concrete indicators. Mercury plays the role of translating vague ideals into measurable metrics (for example, KPIs). In other words, our definition of success can be called “a structure where the Sun’s direction is backed by Jupiter’s philosophy, designed to be sustainable with Venus’s joy, and its current location measured by Mercury’s KPIs.”

Note: KPI is a Key Performance Indicator for managing the process toward achieving the final goal. If the final goal is “to feel the best by climbing Mt. Fuji,” then it’s the scheduled arrival times, physical condition, mood, and other self-evaluations for the 6th, 7th, 8th, and 9th stations.

Philosophy and Operation, and “When Things Just Won’t Work” Now, let’s return to the first question. Are the conditions for success the work of Jupiter and Venus, or the work of Mars and Saturn?

As you already understand, this is not an either/or question. The words that describe the conditions of success themselves (growth, abundance, joy) certainly belong to the vocabulary of Jupiter and Venus. However, the majority of the process of implementing that in reality is driven by the steady work of Saturn (limitation, repetition) and Mars (severance, trial).

Therefore, the most realistic and effective approach is to grasp it as a division of roles: “Philosophy and goal setting are Jupiter/Venus,” “Daily operations are Saturn/Mars.”

So, what should we think “when things just don’t work out”?

In astrology, this is grasped on two levels. One is the concept of Fortune (luck, environment) and Spirit (will, discretion). The other is specific timing theory.

When environmental factors beyond our control (Fortune) and an inappropriate time for “that activity” due to external factors (for example, the season; and transits or profections) arrive, pushing forward blindly will only lead to exhaustion. At such times, “not mistaking the ‘type of game’ you’re in” is more important than anything else.

Also, depending on the time of birth in an individual’s horoscope, the quality of hardship changes depending on whether it is a day or night birth. For example, astrologically, it is thought that people born at night tend to feel Saturn’s difficulties more harshly, and people born during the day feel Mars’s difficulties more harshly.

Therefore, when you feel you cannot do anything, first think, “It’s all Mars and Saturn’s fault,” and stop blaming yourself. That is not stopping thought; it is the first step to becoming calm. And it is from there that the wisdom of astrology is truly utilized. Discerning “What should I let go of now, what should I wait for, and what should I concentrate on?” That itself is the strategic use of astrology for navigating times of headwind.

Practical Work for Using the Stars as a Compass Finally, I will propose a minimal practical framework for bringing this discussion into daily life.

Definition of Success (Sun, Jupiter, Venus, Mercury) Write it out in one sentence. Example: “”

Clarification of Constraints (Saturn) Decide the maximum time and funds that can be used for this project, and the “non-negotiable” quality conditions.

Trial Plan (Mars) Assuming “at least 3 failures,” decide the number of prototypes and their respective deadlines first.

Fuel Check (Venus) To continue the activity, build rewards for yourself (comfortable time, experiencing beautiful things, talking with friends, etc.) into your schedule.

Connection to Meaning (Jupiter) Write down, “Why am I doing this?” linked to your own life’s story. It becomes the origin point to return to when you are lost.

Rhythm (Moon) Fix weekly and monthly check-in dates on the calendar. Turn the cycle with the power of habit, not influenced by emotions or moods. Now, this kind of content has already been introduced in most books, and a sufficient amount of text is overflowing in the world. So, isn’t the actual situation that you are tired of hearing sweet words like, “Astrology, when handled strategically, is a compass to understand your own microcosm and enjoy navigating the voyage of life”?

Moving away from the preconceptions lurking behind the word success, the practice of “failure,” “continuation,” and “decision” is the most effective method in the physical world. When that practice is involved, astrology becomes a compass that assists action.

A Guidebook to the History of Horary Astrology

ホラリー占星術史ガイドブック A Guidebook to the History of Horary AstrologyThe idea that the stars can answer a specific question is by no means a modern invention. In the first century AD, the astrologer Dorotheus of Sidon, in the fifth book of his influential work Carmen Astrologicum, referred to a method that can be considered the prototype of horary astrology. For a time after Dorotheus, however, major astrologers left no written records of a practice designed to answer specific questions.

Entering the Middle Ages, the center stage of astrology shifted to the Arab world. At that time, while Japan was in its Nara and Heian periods, ancient knowledge that had been scattered was translated from Greek and Persian into Arabic within the Islamic sphere. It was during this era that astrology was once again systematized and integrated as a scholarly discipline, and horary astrology, in a form close to what we know today, was established. These works were later translated into Latin, thereby passing on astrological knowledge to Europe. During the Renaissance, astrology was taught alongside astronomy in universities, and giants of astronomical history such as Copernicus, Brahe, Galileo, and Kepler all studied the subject. In those days, astrology and astronomy were viewed as closely related fields of study.

A turning point arrived in the 17th century. The English astrologer William Lilly published Christian Astrology, the world’s first comprehensive guide to horary astrology written in English. Ironically, it was precisely at this time that the fate of astrology in the West began to change. With the rise of modern science, astrology was gradually excluded from the category of “science,” losing the support of intellectuals and the culturally influential. The era when astrology and astronomy were one came to a close, and stargazing came to be treated as mere superstition or entertainment.

Nevertheless, the embers of the tradition of questioning the stars were never completely extinguished. Around the time the Meiji government was established in Japan, a new astrological boom was taking place in Europe and America, fueled by the rise of Theosophy and interest in Eastern thought. Then, in the latter half of the 20th century, horary astrology experienced a revitalization. A movement to resurrect Lilly’s classical methods gained momentum, leading to a revival of traditional astrology centered in the UK and the US. This trend eventually reached Japan, where translated works and specialized courses on horary astrology became available.

For those who wish to delve deeper, the appendix provides a guide to further reading, including books and articles, as well as alternative theories and additional reflections on the topics discussed in the main text.

特定の質問に星が答える――その発想は決して近代の産物ではありません。紀元1世紀の占星術師シドンのドロテウスは著書『占星詩』第五巻「質問と始まり」において、ホラリー占星術の原型ともいえる方法に言及しました。その後しばらく主要な占星術師たちは、特定の質問に答える占星術について何も書き残しませんでした。

中世に入り占星術の舞台はアラビア世界へと移ります。その頃の日本は奈良・平安時代。当時のイスラム圏で、散逸していた古代知識がギリシア語やペルシア語からアラビア語に翻訳され、占星術は再び学問体系として整理・統合されました。現在の形に近いホラリー占星術が確立したのはこの時代です。やがて、それらの成果はラテン語へ翻訳され、占星術の知識はヨーロッパへ受け継がれました。ルネサンス期の大学では天文学と共に占星術が教えられ、コペルニクスやブラーエ、ガリレオ、ケプラーといった天文学史上の巨人たちも占星術を学んでいます。占星術は当時、天文学と地続きの学問分野でした。

転機が訪れたのは17世紀のことです。イングランドの占星術師ウィリアム・リリーが世界で初めて英語による本格的なホラリー占星術の手引書『クリスチャン・アストロロジー』を出版しました。しかし皮肉にも、まさにこの頃から西洋における占星術の運命は転換します。近代科学の台頭により、占星術は次第に「科学」のカテゴリーから外され、知識人や文化人の支持を失い下火になっていきました。そして、占星術と天文学が一体であった時代は終わりを告げ、星占いは迷信や娯楽として扱われるようになります。

それでも星に問う伝統の火種が完全に消えたわけではありません。日本で明治政府が樹立した頃、欧米では神智学や東洋思想の興隆とともに新たな占星術ブームが訪れます。そして20世紀の後半、再びホラリー占星術が息を吹き返しました。リリーの古典的手法を現代に甦らせようという動きが起こり、英米を中心に古典占星術の復興運動が展開されたのです。この流れは日本にも伝わり、ホラリー占星術の翻訳書や専門講座が提供されるようになりました。

資料篇では、さらに学習したい方に向けて書籍や論文、本篇に対する異説や考察を紹介します。

ホラリー占星術史ガイドブック

Web app Sphere 10, Visualize Astrology, Understand the Sky

Sphere10 is a web application that visualizes the positions of planets and zodiac signs on the celestial sphere. Enjoy!

Controls

[_] Minimize controls
▶ Play
■ Stop
▶▶ Fast Forward
◀◀ Reverse Play

Rotation:Linked to mouse operation:

Horizontal: Adjusts the horizontal (left-right) rotation of the celestial sphere.
North/South: Adjusts the vertical tilt (up-down) of the celestial sphere.

Indicator

Meridian: The vertical line connecting north and south on the celestial sphere.
Equator: Represents the celestial equator, aligned with Earth’s axis of rotation.
Ecliptic: The apparent path of the Sun across the sky.
Zodiac: The belt along the ecliptic divided into 12 zodiac constellations (signs), extending approximately 8-9 degrees north and south of the ecliptic.
RA (Right Ascension): Longitudinal lines along the celestial equator.

Auxiliary

Fixed Stars: Shows background fixed stars.
Transparent: Makes the celestial sphere transparent (may appear to rotate in reverse).
Planet Labels: Toggle display of planet names on/off.
Flip ◀|▶: Switch viewing the celestial sphere.
Direction: Toggle display of cardinal directions (N, S, E, W) on/off.

Setting Planetary Positions

Date: By specifying a date and time, the positions of planets and the Moon for that moment will be displayed on Ecliptic

Tips for Beginners

Play with the controls to observe how the starry sky corresponds with horoscope charts.
Displaying the Zodiac and planet names helps clearly visualize their spatial relationships.

星空とホロスコープで遊ぶWebアプリ

[updated:2025-03-08 / released:2025-03-08]

スフィア10立体ホロスコープは、立体的な天球に惑星や星座(サイン)を表示し、遊びながら惑星や12サインを理解するツールです。

サポートグループ

スフィア10の活用方法や、アップデート、β版利用、他の天文占星ツールを共有します。
サポートグループはこちらへ(Googleクラスルーム|常時入退会自由)。現在は日本語対応のみです。


左側メニューについて

動作

[_]最小化
▶ 再生
■ 停止
▶▶倍速
◀◀逆再生

回転 Rotation

マウス操作に連動します
水平 (Horizontal):天球の水平(左右)方向への回転を調整します。
南北 North/South:天球を上下に傾ける角度を調整します。

指標 Indicator

Meridian(子午線):南北を結ぶ垂直方向のライン
Equator 赤道:天の赤道を表すライン 地球の自転軸
Ecliptic 黄道:見かけ上の太陽の通り道。
Zodiac 獣帯:黄道帯にそった12星座(サイン)の区分。黄道を中心に南北8-9度の幅があります。
RA 赤経:天の赤道に沿った経線。

補助 Auxiliary

Fixed Stars 恒星:背景の恒星の表示
Transparent 透明:天球を透過表示(逆回転しているように見える場合があります)
Planet Labels 惑星名:惑星名の表示ON/OFF
反転 Flip ◀|▶:東西を「反転」し、ホロスコープと似た表示にします。
Direction 方角:東西南北の方角表示のオン・オフ

惑星位置の設定
惑星位置 Date
日時を指定すると、その日時での惑星や月の位置が表示されます。

使い方のポイント(初心者向け)

実際に操作して、星空とホロスコープの関係を確認してみましょう。
Zodiac(獣帯)や惑星の名前を表示すると、星座と惑星の位置関係をつかみやすくなります。