Answer: You must be at the North Pole. Directly overhead of the North Pole hovers Polaris. As the Earth rotates around its axis, the stars revolve counterclockwise around Polaris. Each star traces a concentric circle around the central point exactly overhead. (1) 2. (The Copernican system) What is the basic difference between the Ptolemaic and Copernican models? Why is the Ptolemaic model considered incorrect? Answer: Copernicus was a Polish astronomer and mathematician who was a proponent of the view of an Earth in daily motion about its axis and in yearly motion around a stationary sun.
This theory profoundly altered later workers’ view of the universe, but was rejected by the Catholic Church. (2) Ptolemy like Aristotle believed that the earth was the center of the universe. He believed the Earth was fixed and around which a sphere of fixed stars rotates every day, including the sun, moon and all of the other planets. Using a telescope, Galileo proved that Copernicus was correct about the sun being the center of the universe with Earth and all other planets revolving around it. 3.
(The Copernican system) Ancient astronomers were troubled by variations in the brightness of the various planets with time. Does the Ptolemaic or the Copernican model account better for these variations? Answer: The Copernican model better explains these variations than the Ptolemaic model. Ptolemy and Aristotle proposed that the heavens were composed of 55 concentric circles and that celestial bodies traveled along these circles at different velocities with the earth located at the center of the concentric spheres. (3)
Copernicus proposed that the Earth and all other planets traveled in elliptical orbits around the sun. Because the Earth is in an elliptical orbit, planets will appear brighter when earth is at the apex of its elliptical orbit and will be closer to the other planets, thus, making them seem brighter. 4. (The tides) The earth takes almost exactly 24 h to make a complete turn on its axis, so we might expect each high tide to occur 12 hours after the one before. However, the actual time between high tides is 12 h 25 min.
Can you account for the difference? Answer: As the Earth rotates around its axis once every 24 hours, the Moon appears above the Earth approximately after an interval of 24 hours and 50 minutes. The 50 minute time delay is caused by the fact that while the Earth has completed one rotation within 24 hours, the Moon has also moved forward in its own orbit. This is the reason why the time interval between successive high tides or between successive low tides is 12 hours and 25 minutes.
The time gap between one high tide and the following low tide is approximately 6 hours and 12. 5 minutes. (4) References: (1) http://www. sky-watch. com/astronomy-guide/watching-from-the-ground. html Watching the Celestial Sphere From the Ground (2) http://www-groups. dcs. st-and. ac. uk/~history/Mathematicians/Copernicus. html Nicolaus Copernicus (3) http://csep10. phys. utk. edu/astr161/lect/retrograde/aristotle. html The Universe of Ptolemy and Aristotle (4) http://www. essortment. com/all/tidesmoon_rdky. htm Tides and the Moon