The Four Models of the Universe: Copernican, Ptolemaic, and Two New Models (Two Versions of the New Model), Big Observation (No Details) from Job's blog

The question of how the universe operates has fascinated humanity for centuries. Two famous historical models - the Copernican and Ptolemaic systems - provided early frameworks for understanding the cosmos. Two new models - each presenting a unique perspective on the structure and functioning of the universe. Differences and similarities between these four models.

1. The Copernican Model

Key Features:

Heliocentric (Sun-centered) system

All planets, including Earth, orbit the Sun in elliptical paths (there is a modern version of this).

The Earth rotates on its axis once every 24 hours, causing day and night.

Seasons are explained by the Earth's axial tilt as it orbits the Sun.

Stars are considered to be stationary, located far away from the planets.

Strengths:

Provided a mathematically simpler explanation for planetary retrograde motion.

Introduced the concept of elliptical orbits based on Johannes Kepler’s later refinements.

Explained the phases of Venus and other planetary phenomena better than prior models.

Weaknesses:

Initially, the Copernican model was resisted by the Church and many scholars for challenging the geocentric view.

It still required some use of epicycles (smaller circular motions) to explain planetary movements.

The Earth's northern and southern hemispheres are at different distances from the Sun in their summer due to the Earth's elliptical orbit around the Sun.

2. The Ptolemaic Model

Key Features:

Geocentric (Earth-centered) system.

Planets, including the Sun, orbit the Earth in a series of epicycles (small circles) within their main orbits (called deferents).

Stars are fixed in the outermost celestial sphere, which rotates around the Earth once every 24 hours.

The Sun moves along a fixed path relative to Earth, accounting for day and night.
 
Strengths:

Provided an effective explanation for the observed retrograde motion of the planets.

Aligned with the religious and philosophical beliefs of the time, positioned Earth as the center of the universe.

Weaknesses:

Required complex calculations and the addition of epicycles, making it less efficient than later models.

Did not provide a clear explanation for the changing phases of Venus or certain observations of planetary motion.

3. The First Version of the New Model

Key Features:

Geocentric system.

Spiral Orbit: The Sun follows a spiral path around Earth, completing one full rotation every 24 hours. The Sun moves higher or lower relative to the Earth’s equator, creating the familiar progression of the seasons.

The stars rotate around Earth in approximately 24 hours and 4 minutes, slightly slower than the Sun, allowing the Sun to pass through the "oblique" part of the Zodiac (with/reason of the Sun's spiral orbit) in one year.

Planets (referred to as cold stars) and stars (hot stars) are distinct, with planets following their own orbits around Earth.

Strengths:

Provides an alternative explanation for the daily movement of the Sun and stars, with the Sun maintaining a steady path and creating the four seasons.

Accounts for the motion of stars and planets through a different mechanism, with planets seen as cold stars.

Weaknesses:

This contradicts modern astrophysics, which places the Sun at the center of the solar system.

4. The Second Version of the New Model

Key Features:

Geocentric system where the Sun follows a circular inclined orbit around Earth, aligned with the Zodiac in 365 days. The Sun moves higher or lower relative to the Earth’s equator, creating the familiar progression of the seasons.

The Earth rotates counterclockwise around its axis every 24 hours, explaining the day-night cycle.

Fixed stars (hot stars) remain stationary in the sky, while planets (cold stars) orbit Earth in their paths.

The Sun’s annual orbit around Earth creates the seasons, similar to the first model but with a more circular and inclined orbit.

Strengths:

Simpler than the Ptolemaic system, avoiding the need for epicycles.

Provides an explanation for both daily and annual solar movement, ensuring the creation of seasons without an axial tilt of Earth.

Weaknesses:

Similar to the first new model, it does not align with modern astrophysical data regarding planetary distances and movements.

Size and Distance of the Sun and Planets

Ptolemaic Model: The Sun is closer than the stars but farther than the Moon, orbiting Earth in a circular path.

Copernican Model: The Sun is 109 times larger than Earth and is located millions of kilometers away.

New Models (Both Versions): The Sun is two to three times larger than Earth and follows either a spiral or circular inclined orbit around Earth, remaining much closer than in the Copernican system.

New Models (Both Versions): Stars (hot stars) are twice the size of Earth, and planets (cold stars) are  2 times smaller than Earth.

Moon’s Orbit:

New Models (Both Versions): The Moon remains at the same distance from Earth, which is about 384,400 kilometers, and orbits in approximately 29.5 days. The Moon’s phases and behavior are identical to those in the Copernican system.

Conclusion: Four Models of the Universe

The Copernican and Ptolemaic models have laid the foundation for understanding the cosmos. The Copernican model revolutionized astronomy by placing the Sun at the center, while the Ptolemaic system offered a geocentric view. The two new models provide alternative explanations that combine ancient geocentric beliefs with different mechanisms for the Sun’s orbit, daily cycles, and the movement of stars and planets. While modern science favors the Copernican model, these new models present ideas about the universe’s structure, offering a fresh perspective on celestial mechanics.