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The ModelEccentricity

Eccentricity

Eccentricity measures how elliptical Earth’s orbit is. A value of 0 would be a perfect circle; higher values mean a more elongated ellipse. Earth’s current eccentricity is 0.01671022 - a nearly circular orbit.


What Eccentricity Means in Practice

The eccentricity value (0.01671022) represents the offset distance between the center of Earth’s orbit and the Sun, expressed as a fraction of the orbital radius (1 AU).

MeasurementValue
1 AU (mean Earth-Sun distance)149,597,870.7 km
Eccentricity (J2000)0.01671022
Offset distance2,499,813 km
Perihelion distance~147.1 million km
Aphelion distance~152.1 million km
Difference~5 million km

This means:

  • At perihelion (closest, ~January 3): Earth is ~147.1 million km from the Sun
  • At aphelion (farthest, ~July 4): Earth is ~152.1 million km from the Sun
  • Earth receives about 7% more solar energy at perihelion than at aphelion

The 20,868-Year Cycle

In the Holistic Universe Model, eccentricity changes in a predictable 20,868-year cycle - not the ~100,000 and ~400,000-year cycles proposed by Milankovitch theory.

The Mechanism

Earth and PERIHELION-OF-EARTH orbiting in opposite directions

Two motions work in opposite directions:

MotionDirectionPeriod
Earth around EARTH-WOBBLE-CENTERClockwise~25,684 years
PERIHELION-OF-EARTH around SunCounter-clockwise~111,296 years

Because they move in opposite directions, they meet more frequently than either cycle alone:

Meeting frequency = 1/25,684 + 1/111,296 = 1/20,868 Therefore: They meet every 20,868 years

This is the perihelion precession cycle.

Why Alignment Affects Eccentricity

The PERIHELION-OF-EARTH defines where Earth’s closest approach to the Sun occurs. Earth orbits the EARTH-WOBBLE-CENTER at a small radius (~214,000 km).

When Earth and PERIHELION-OF-EARTH are on the same side of EARTH-WOBBLE-CENTER:

  • Their distances add together
  • Maximum eccentricity (~0.0167)

When Earth and PERIHELION-OF-EARTH are on opposite sides:

  • Their distances partially cancel
  • Minimum eccentricity (~0.0139)

Eccentricity Values

ParameterValueNotes
Current eccentricity (J2000)0.01671022Measured, NASA Planetary Fact Sheet
Mean eccentricity0.015313Model-derived center of oscillation
Maximum eccentricity~0.0167At winter solstice alignment
Minimum eccentricity~0.0139At summer solstice alignment
Variation amplitude±0.00143Half the range
Cycle period20,868 years333,888 ÷ 16

How Mean Eccentricity Was Derived

The mean value (0.015313) cannot be measured directly - we only have observations from recent centuries. It was derived using three constraints:

  1. Minimum eccentricity occurred in ~9188 BC when perihelion aligned with the June solstice
  2. Maximum eccentricity occurred in 1246 AD when perihelion aligned with the December solstice
  3. Current eccentricity (0.01671022) is between max and mean, and decreasing

The 3D Simulation was calibrated to satisfy all three constraints, yielding:

  • Mean = 0.015313 AU
  • Amplitude = ±0.00143 AU

The Solstice Connection

Eccentricity extremes correlate with solstice alignments:

AlignmentEccentricityLast OccurrenceNext Occurrence
Perihelion at December solsticeMaximum (~0.0167)1246 AD~22,114 AD
Perihelion at June solsticeMinimum (~0.0139)~9188 BC~11,680 AD

Why this correlation?

When perihelion aligns with the December solstice (Northern Hemisphere winter), Earth and PERIHELION-OF-EARTH are positioned such that their orbital offsets add together. When aligned with the June solstice, they partially cancel.

Graph showing Earth's eccentricity oscillating between 0.0139 and 0.0167 over a 20,868-year cycle, with maximum at December solstice alignment in 1246 AD

Current Status

We passed maximum eccentricity around 1246 AD. The current value (0.01671022) is:

  • Decreasing toward the mean
  • Will reach minimum (~0.0139) around 11,680 AD
  • Will return to maximum around 22,114 AD

Why Not Milankovitch’s 100k/400k Cycles?

The conventional Milankovitch theory proposes eccentricity cycles of ~100,000 and ~400,000 years. The model proposes a simpler 20,868-year cycle instead. Here’s why:

Five Problems with the Conventional Theory

ProblemExplanation
1. No actual ~100k cycleMilankovitch calculated ~95k and ~125k cycles, not ~100k. The “~100k” is a simplification that doesn’t match his actual work.
2. No ~400k pattern in dataGeological temperature records over the past 1.2 million years  show no ~400k periodicity. This is called the “100,000-year problem.”
3. Insufficient energy effectEccentricity changes affect total annual insolation by only ~0.2%. This is too small to explain observed ice age cycles.
4. Theoretical, not measuredThe ~95k, ~125k, and ~400k cycles are calculated from Jupiter-Saturn gravitational resonance models, not measured from data.
5. Missing inclination precessionMilankovitch did not know about inclination precession (~67k years vs ecliptic, ~111k vs ICRF). Without this, Jupiter-Saturn resonance calculations are incomplete.

The ~100k Pattern in Ice Cores

Ice core data does show a roughly ~100,000-year pattern in glacial cycles. The model proposes this actually reflects the inclination precession cycle (~111,296 years), not eccentricity:

~100,000 years in ice cores ≈ 111,296 years (inclination precession)

The ~10% discrepancy may be due to dating uncertainties in ice core chronology.

Graph comparing the model's 20,868-year eccentricity cycle with ice core data, showing how the ~100k pattern may reflect inclination precession rather than eccentricity

Comparison with Standard Formulas

The model matches the current observed eccentricity, but doesn’t match the theorized values:

Long-term comparison of model's eccentricity predictions versus standard Milankovitch theory, showing divergence beyond recent centuries where direct measurements exist

Long-term predictions differ because:

  • The model uses a 20,868-year cycle
  • Standard theory uses ~100k/400k cycles
  • Direct measurements only exist for recent centuries

Important: Both the model’s predictions and standard Milankovitch predictions for ancient/future eccentricity are theoretical. Neither can be directly verified for times before ~1500 AD.


Climate Implications

Eccentricity affects Earth’s climate through two mechanisms:

1. Total Annual Energy

Higher eccentricity means Earth spends more time farther from the Sun (moving slower at aphelion). This slightly reduces total annual solar energy received.

EccentricityEffect on Annual Insolation
Maximum (0.0167)~0.2% less than circular
Minimum (0.0139)~0.1% less than circular
Difference~0.1%

This effect is small - too small alone to cause ice ages.

2. Seasonal Contrast

The more important effect is when perihelion occurs relative to seasons:

Perihelion TimingNorthern Hemisphere Effect
January (current)Milder winters, cooler summers
July (~11,680 AD)Hotter summers, colder winters

When perihelion occurs during Northern Hemisphere winter (as now), winters are slightly milder. When it occurs during summer, seasonal contrasts increase.


Summary

AspectValue
Current eccentricity0.01671022 (decreasing)
Cycle period20,868 years
Range0.0139 to 0.0167
Maximum alignmentPerihelion at December solstice
Minimum alignmentPerihelion at June solstice
Last maximum1246 AD
Next minimum~11,680 AD

Calculate Eccentricity at Any Year

To calculate eccentricity values for any year, see the Formulas page which provides the complete Excel formula.


Key Takeaways

  1. Eccentricity = orbital elongation - Currently 0.0167, meaning ~5 million km difference between perihelion and aphelion
  2. 20,868-year cycle - From the meeting frequency of two counter-rotating motions
  3. Maximum at winter solstice alignment - When Earth and PERIHELION-OF-EARTH offsets add together
  4. Minimum at summer solstice alignment - When offsets partially cancel
  5. Currently decreasing - We passed maximum around 1246 AD
  6. Simpler than Milankovitch - One cycle (20,868 years) instead of multiple overlapping cycles (100k/400k)

Continue to Days & Years to learn how these cycles affect the length of our days and years.

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