Part 17: Astronomical Tables Part 2
Mercury and Venus are inferior planets—they orbit between Earth and Sun. Their retrograde motion occurs during inferior conjunction (when passing between Earth and Sun), requiring special Seeghrochcha (apogee) calculations.
Why Special Tables?
Unlike superior planets (Mars, Jupiter, Saturn), Mercury and Venus have mean positions equal to the Sun's. Their true positions require apogee adjustments. These product tables streamline the calculation process by providing pre-computed motion values.
Key Concept: Seeghrochcha = Apogee (point in orbit farthest from Earth). Required for calculating Chesta Bala (motional strength) of Mercury and Venus.
Epoch Data (1 Jan 1900, 0h, 76° E):
- Adopted Apogee: 164°
- Mean Position: Same as Sun
- Aphelion: 220°.5
Correction: +6°.67 − 0.00133t (where t = years from epoch)
| Days | Units | Tens | Hundreds | Thousands | Ten Thousands |
|---|---|---|---|---|---|
| 1 | 4.09 | 40.92 | 49.23 | 133.32 | 243.18 |
| 2 | 8.18 | 81.84 | 98.46 | 264.64 | 126.36 |
| 3 | 12.28 | 122.77 | 147.69 | 36.95 | 9.54 |
| 4 | 16.37 | 163.69 | 196.93 | 169.27 | 252.72 |
| 5 | 20.46 | 204.62 | 246.16 | 301.59 | 135.90 |
| 6 | 24.55 | 245.54 | 295.39 | 73.91 | 19.08 |
| 7 | 28.65 | 286.46 | 344.62 | 206.34 | 262.26 |
| 8 | 32.74 | 327.38 | 33.85 | 338.50 | 145.44 |
| 9 | 36.83 | 8.31 | 83.09 | 110.86 | 28.63 |
How to Use Mercury's Table
- Calculate Ahargana (days from epoch) for birth date
- Break down interval into thousands, hundreds, tens, units
- Look up corresponding values from each column
- Sum all values + adopted apogee (164°)
- Add correction: 6.67 − 0.00133 × (years from 1900)
- Reduce modulo 360° for final apogee position
- Use in Chesta Bala formula: (Apogee − Average of True & Mean Long.) ÷ 3
Epoch Data (1 Jan 1900, 0h, Civil Time):
- Mean Position: Same as Sun
- Apogee at Epoch: 328°.5
- Aphelion: 79°.9
Correction: −5° − 0.0001t (where t = years from epoch)
| Days | Units | Tens | Hundreds | Thousands | Ten Thousands |
|---|---|---|---|---|---|
| 1 | 1.60 | 16.02 | 160.21 | 162.15 | 181.46 |
| 2 | 3.20 | 32.04 | 320.43 | 324.29 | 2.93 |
| 3 | 4.81 | 48.06 | 120.64 | 246.44 | 184.39 |
| 4 | 6.41 | 64.09 | 280.86 | 288.52 | 5.86 |
| 5 | 8.01 | 80.11 | 81.07 | 90.73 | 187.32 |
| 6 | 9.61 | 96.13 | 241.29 | 252.88 | 8.79 |
| 7 | 11.21 | 112.15 | 41.50 | 55.02 | 190.25 |
| 8 | 12.82 | 128.17 | 201.72 | 217.17 | 11.71 |
| 9 | 14.42 | 144.19 | 1.93 | 19.32 | 193.18 |
How to Use Venus' Table
- Calculate Ahargana for birth date
- Break down interval into component digits
- Sum corresponding table values
- Add epoch apogee (328.5°)
- Subtract correction: 5 + 0.0001 × (years from 1900)
- Reduce modulo 360°
- Apply to Chesta Bala formula
Let's find Venus' Seeghrochcha for the Standard Horoscope (16 Oct 1918, 7:30 AM):
Step 1: Ahargana = 1918 - 1900 = 18 years × 365 = 6570 + 4 (leap years) + 289 (days to Oct 16) = 6863 days
Step 2: Break down 6863:
- 6000 days (thousands column, row 6): 252.88
- 800 days (hundreds column, row 8): 201.72
- 60 days (tens column, row 6): 96.13
- 3 days (units column, row 3): 4.81
Step 3: Sum = 252.88 + 201.72 + 96.13 + 4.81 = 555.54°
Step 4: Add epoch: 555.54 + 328.5 = 884.04°
Step 5: Subtract correction: 884.04 − (5 + 0.0001 × 18) = 884.04 − 5.0018 = 879.04°
Final: 879.04° mod 360° = 159.04° (Venus Seeghrochcha)
Without product tables, calculating inferior planet apogees requires:
- Daily mean motion formulas (complex arithmetic)
- Multiplication by interval in days (error-prone for large numbers)
- Multiple correction factors
Product tables streamline the process:
- Pre-computed values eliminate repetitive calculation
- Lookup is faster and more accurate than manual computation
- Reduces human error in astronomical calculations
Modern Note: Today, ephemeris software computes these values instantly. However, understanding the underlying astronomy deepens appreciation for planetary motion patterns and strengthens prediction accuracy when interpreting Chesta Bala results.
Part 18 concludes the series with a comprehensive index of Sanskrit technical terms—your permanent glossary for Shadbala terminology. From Abda (year) to Yuddha (planetary war), all key concepts defined in one reference.