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du Chevreul on the Position of the Earth
du Chevreul argued that the shape of the Earth was spherical for many reasons:


 * 1) A sphere can hold a lot in it, and it can rotate around its axis. The Earth is massive and contains so much within it. It also rotates on its axis. Therefore it must be a sphere.
 * 2) Spheres cannot be penetrated and thus do not contain a vacuum. Vacuums do not exist in earth’s nature; therefore it must be a shape that is impenetrable.
 * 3) Based on natural events such as gravity, the movement of the earth’s crust, and meteorological events such as cloud formation, it can be concluded that the Earth must have a spherical shape.
 * 4) Stars are fixed, and yet each has a unique distance from the earth. Additionally, stars rise and set during the night, and their distance with respect to the horizon changes as one changes his/her position on the Earth.
 * 5) During a lunar eclipse, the Earth’s shadow is circular in shape.

du Chevreul rejected the Copernican theories on the system of the universe for many reasons. First, he believed that the Earth was at the center of the universe and did not orbit. He used the teachings of Plato, Aristotle, and other philosophers and astrologers who asserted this geocentric idea. Second, he looked to passages in the Bible for theological support. One passage stated that when God created the Earth, he did not intend for it to move. Another passage referenced the miracle witnessed by the biblical character Joshua in which God halted the movement of the sun and the moon. du Chevreul also argued that Copernicus’s theories contradicted the physics concerning the motion of a single and simple body. Even though he claimed that Earth was at the center of the universe, du Chevreul also claimed that Venus and Mercury orbited the Sun. The root of this theory was his claim that spots seen on the Sun are actually Venus and Mercury rather than the fact that they have phases like the moon.

du Chevreul on the Heavens
On the heavens, particularly on the question of whether or not they can change, du Chevreul did not give a straight answer, but he did theorize that the brightness of the stars indicated how dense and how rare they were. He classified stars into two categories: stars that did not move (fixed) and stars that did move (wandering). He classified the planets, the Sun, and the Moon as wandering stars. Following in the steps of Aristotle and Plato, he confirmed that there are seven wandering stars: Saturn, Jupiter, Mars, the Sun, Venus, Mercury, and the Moon. However, he also counted the four Medician stars that orbit Jupiter, which were discovered by Galileo, and he counted the two planets that orbit Saturn. Therefore, he counted thirteen planets in all.

du Chevreul believed that Aristotle’s observations should in general be taken into consideration; however there were some points where du Chevreul disagreed with him such as the number of levels in the heavens. According to Aristotle, along with Plato, the number of levels of the heavens was at least eight, which included Saturn, Venus, Mercury, Jupiter, Mars, the Sun, the Moon, and the stars. du Chevreul had a different theory in which he counted only five levels: Saturn, Jupiter, Mars, the Sun, and the Moon. Unlike his predecessors who either argued that Venus and Mercury were above the Sun or below it, du Chevreul asserted all of the above. Since Venus and Mercury orbit the Sun, du Chevreul deduced, they could be found both above and below it. Thus, Venus and Mercury were located within the Sun’s level and did not have levels of their own. The following are du Chevreul’s levels of the heavens in order, with Earth located at the center:


 * 1) The Moon
 * 2) The Sun, in which Mercury and Venus circulate around the sun
 * 3) Mars
 * 4) Jupiter, in which the four Medicean stars circulate around Jupiter
 * 5) Saturn, in which two planets circulate around Saturn

Keeping in line with biblical scriptures, du Chevreul claimed that above all these levels was where God resigned, known as the Empyrean Heaven.

du Chevreul's observations were in line with Galileo’s observations with one exception. Galileo discovered that the moon had mountains and valleys that were similar to those of the earth. du Chevreul’s response to this was that if the moon did have mountains and valleys, then the moon would also have areas of empty space, which nature does not allow. Instead, du Chevreul believed that what Galileo had saw were actually the varying densities of the moon. Just as a star’s brightness indicates its density and rarity, so does the variance of brightness on the moon. Another astronomer’s observations that du Chevreul rejected were those of Tycho Brahe. He not only rejected the Tychonic description of the heavens, but he also rejected Brahe’s theory that Mars was below the sun. Additionally, to accept Brahe’s theories of the universe was to reject eccentrics and epicycles, which du Chevreul was not willing to do. He argued for the existence of eccentrics because observations had shown that as planets orbited, their distance from the center of the universe varied. Epicycles, he claimed, revealed the idea that the planets vary in their speed as they orbit around the center of the universe. His model of epicycles and eccentrics was three dimensional and spherical. This was consistent with the Aristotelean and Ptolemaic models which were popular in Paris during the 1600s.