Comprehensive History and Development of Solar System Models

Heliocentric Model: A model of the Solar System with the Sun categorized at the absolute centre.
Geocentric Model: A model of the Solar System with the Earth categorized at the absolute centre.
Do Now Activity: The identification of models marked $A$ to $F$ as either Heliocentric or Geocentric models, based on the central body of the system.

Lesson Objective: To investigate and observe how the ideas of scientists regarding the Solar System have developed and evolved over historical time.
Modern Cultural Context: References include the television program "Adam Ruins Everything" on the network "truTV" and the historical period known as "The Space Race," described as "Starting at the End."

The Hebrews: Proposed that the Universe was created by God over a duration of $6$ days, originating from a formless void.
The Greeks: Initially conceptualized the start of the Universe as formless "Chaos." This was believed to be followed by the emergence of gods who established order in the cosmos and engaged in internal conflict to maintain control.
India: Posited that there was originally neither form nor substance. Father Sky and Mother Earth were believed to have conceived the gods, who subsequently shaped the earth. It is noted that sexual interaction among deities is a common characteristic of various creation stories.
Egypt: Viewed the Universe as a massive rectangular box. Egypt was situated at the center of this box. The Sun-god, Ra, was believed to ride around a celestial river once every day. Star lamps were conceptualized as being suspended from the top of the box.

Aristotle ( $384\,BC - 322\,BC$ ): An ancient Greek philosopher who proposed the influential Geocentric model. He asserted that the Earth was at the centre of the Solar System and that every other celestial object orbited around it.
Aristarchus of Samos ( $310\,BC - 230\,BC$ ): Often cited as a great mind who remains largely unknown to the general public. He proposed a theory of a heliocentric universe that predates the work of Copernicus and Galileo. His ideas influenced many Greek philosophers, including Copernicus, but were ultimately not accepted during his time due to the overwhelming influence of other philosophers who supported the Geocentric model.
Ptolemy ( $150\,BC$ ): An ancient Greek philosopher who observed that certain celestial movements did not align with Aristotle’s original ideas. To account for these discrepancies in planetary movement, he introduced the concept of Epicycles. Despite these modifications, he maintained the Geocentric view that the Earth was the center of the Solar System.

Nicolas Copernicus ( $1473 - 1543$ ): Identified as the first scientist to suggest that the Sun, rather than the Earth, was at the centre of the Solar System. He is also credited as the first scientist to correctly order the planets according to their distance from the Sun.
Galileo Galilei ( $1564\,AD - 1642\,AD$ ): An Italian scientist who focused extensively on the technical improvement of the telescope. These advancements allowed him to observe celestial phenomena previously invisible to other scientists. His key contributions include:
- Being the first person to identify Sunspots.
- Being the first person to see the four brightest moons of Jupiter.
- Noting that the visual phases of Venus change in the same manner as the phases of our Moon.
- Making major advances in telescope design specifically noted around $1594\,AD$ .

Johannes Kepler ( $1571\,AD - 1630\,AD$ ): A German scientist who developed three laws to explain the movement of planets. His most significant contributions include:
- The realization that planetary orbits are ellipses rather than perfect circles.
- The discovery that planets do not move at a constant speed; rather, their speed is directly related to their distance from the Sun. These ideas form a core part of current scientific thinking and were formalized around $1600\,AD$ .
Sir Isaac Newton ( $1643\,AD - 1727\,AD$ ): An English scientist famous for developing the Universal Theory of Gravity. This theory provided a physical explanation for Kepler’s observational laws and proved that Kepler’s models were accurate.

William Herschel ( $1738\,AD - 1822\,AD$ ): An English scientist who discovered the planet Uranus by accident. Although it had been observed by others previously, it was historically mistaken for a star. Because Uranus is not visible from Earth without a telescope, it remained unknown to ancient civilizations.
Edwin Powell Hubble ( $1889\,AD - 1953\,AD$ ): Radically transformed our view of the Universe. He was the first to suggest that the universe is not static but is expanding, a discovery documented in $1929\,AD$ . This observation served as the foundation for the development of the ‘BIG BANG’ theory regarding the origins of the universe.

$1000\,BC$ to $0$ :
- Aristotle: Proposes Earth-centered solar system.
- Aristarchus ( $approx. 200\,BC$ ): Suggests Sun-centered solar system.
- Ptolemy ( $approx. 150\,BC$ ): Introduces epicycles; maintains Geocentric model.
$0$ to $2000\,AD$ :
- Nicolas Copernicus: Suggests Sun-centered solar system.
- Galileo Galilei ( $1594\,AD$ ): Advances in telescope design.
- Johannes Kepler ( $1600\,AD$ ): Defines three laws of motion and elliptical orbits.
- Isaac Newton: Proposes planetary gravity.
- William Herschel: Discovers Uranus.
- Edwin Hubble ( $1929\,AD$ ): Discovers the expanding universe.