9. Why do we use constellations in astronomy? 10. Which scientists supported the Geocentric Model of the Solar System? 11. What is the starting point of Modern Astronomy ? 12. The Sun appears in front of a different constellation each month due to __ a) the Earth's rotation on its axis. b) the Earth's orbital motion around the Sun. c) the Sun's motion around the center of the Milky Way Galaxy. d) precession of the rotation axis of the Earth. 13. If the distance between the Sun and Planet X is 2.43times 10^8 km, what is the period of Planet X in Earth years? 14. If the orbital period of a dwarf planet is 48 years , what is the distance between the Sun and the dwarf planet?

9. We use constellations in astronomy to help us locate and identify celestial objects such as stars and galaxies. Constellations provide a framework for organizing and mapping the night sky, making it easier for astronomers to study and understand the positions and movements of celestial bodies.<br /><br />10. The Geocentric Model of the Solar System was supported by ancient Greek philosophers such as Aristotle and Ptolemy. They believed that the Earth was the center of the universe and that all celestial bodies, including the Sun and planets, revolved around it.<br /><br />11. The starting point of Modern Astronomy is considered to be the heliocentric model proposed by Copernicus in the 16th century. This model, which places the Sun at the center of the Solar System, marked a significant shift from the previously accepted geocentric model.<br /><br />12. The Sun appears in front of a different constellation each month due to the Earth's orbital motion around the Sun. As the Earth orbits the Sun, our perspective from Earth changes, causing the Sun to appear in different constellations throughout the year.<br /><br />13. To find the period of Planet X in Earth years, we can use Kepler's Third Law, which states that the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit. Using the given distance of $2.43\times 10^{8}$ km, we can calculate the orbital period of Planet X in Earth years.<br /><br />14. To find the distance between the Sun and the dwarf planet, we can use Kepler's Third Law again. Given the orbital period of 48 years, we can calculate the distance between the Sun and the dwarf planet.