Seasons in Thompson's Vedic Planisphere Model

This explanation details how seasons function within Richard L. Thompson's interpretation of the Bhū-maṇḍala as a planisphere with an off-centered ecliptic.

1. Understanding the Model: A Map, Not a Globe

First, it is crucial to internalize what Thompson is arguing:

The Bhū-maṇḍala as a Planisphere is not a literal, flat, physical disk. Instead, it is a map or a projection of the celestial sphere onto a plane. Think of it like a world map, which is a two-dimensional representation of a three-dimensional Earth.

The "Off-Centered Ecliptic" is a key feature. Thompson argues that in this Vedic planisphere, the ecliptic (the Sun's apparent yearly path) is not concentric with the central Mount Meru. It is displaced or "off-centered." This means the model is a sophisticated cartographic representation, not a naive flat-Earth model.

2. The Mechanism of Seasons in this Model

The fundamental cause of seasons remains the tilt of the Earth's axis relative to its orbital plane. This is an astronomical reality, regardless of how you map the sky.

In Thompson's Vedic planisphere, this axial tilt is represented by the off-centered nature of the ecliptic.

On the map, the Sun doesn't move at a constant distance from Mount Meru (the celestial pole in this projection). Its path brings it closer to and farther from the center at different points.

The point on the ecliptic closest to Mount Meru would correspond to the summer solstice for the northern hemisphere. On the map, the Sun is "high" in the polar region.

The point on the ecliptic farthest from Mount Meru would correspond to the winter solstice for the northern hemisphere. On the map, the Sun is "low," out in the peripheral regions.

The off-centered circle acts as a geometric mechanism to represent the Sun's declination. As the Sun moves around this path, its position relative to the central axis changes, creating the effect of the Sun moving higher and lower in the sky over the year.

Analogy: Imagine a vinyl record on a turntable. The groove is a perfect circle centered on the spindle (the celestial equator). Now, imagine a second, smaller circle (the ecliptic) that is placed off-center. The stylus (the Sun) follows this off-center path. Its changing distance from the spindle (Meru) on this two-dimensional surface represents the changing seasons.

3. Does the Off-Centered Ecliptic "Compensate" on the Projection?

Yes, absolutely. The off-centered ecliptic is the compensation.

You are trying to represent a three-dimensional, tilted celestial phenomenon on a two-dimensional, flat map. A simple, concentric circle for the ecliptic would be inadequate—it would only show the Sun's motion in longitude, but not its changing declination, which is essential for seasons.

The off-centered circle is the geometric solution to this problem. It is the precise way the map "encodes" both the Sun's longitudinal motion and its latitudinal oscillation.

Summary and Conclusion

In Thompson's Vedic cosmology:

Seasons are Real: The model fully accounts for the seasonal cycle.

The Cause is Represented Geometrically: The physical cause (Earth's axial tilt) is not discarded. Instead, its effects are mapped onto a two-dimensional planisphere using the clever device of an off-centered ecliptic path for the Sun.

The Off-Centered Ecliptic is the Key: It is not a flaw but the very feature that allows the flat map to accurately represent the Sun's changing declination. It "compensates" for the limitations of the 2D projection by transforming a tilt in three-dimensional space into a displacement in a two-dimensional diagram.

Therefore, Thompson's interpretation presents the Bhū-maṇḍala not as a primitive cosmological concept, but as a sophisticated and intentional celestial map, where the off-centered ecliptic is the critical element that makes the model work and correctly represent the phenomenon of seasons.