Much of modern Western civilization is derived in one way or another from the ideas of the ancient Greeks and Romans, and this is true in astronomy as well. With heliocentrism, explaining retrograde motion was simple. Describe the motion of Earth called precession Describe Ptolemy’s geocentric system of planetary motion Let us now look briefly back into history. It’s worth noting that one of the reasons heliocentrism replaced geocentrism (the notion that the Earth is in the center of the Solar System) is that geocentrism couldn’t explain the retrograde motion of planets. Another phenomenon is that the other inner planets, and most noticeably Mercury appear to have a retrograde orbit some of the time. All this uncertainty and emotional swinging will make our heads spin, unless we know how to use the energy correctlywhich we are here to explain. (This thought experiment works with different modes of transportation, from walking to cycling to flying in airplanes.) The end of September and the beginning of October bring six planets (Mercury, Jupiter, Saturn, Uranus, Neptune, and Pluto) into retrograde motion. Astronomy Lecture Number 3 Early Models of the Universe Motions of the Planets As we said in the previous lecture, all of the planets orbit the Sun in the same plane, along with the Earth. As the faster car overtakes the slower, it will appear (from the vantage point of the faster car) as though the slower car stops, then moves backward, even though its actual speed has not changed. The heliocentric explanation of the motions of the planets. One travels slightly faster than the other. Retrograde motion occurs when the line rotates clockwise because the Earth passes the planet. Imagine two cars traveling in the same direction in two different lanes. We can actually see this effect on Earth. the planets generally move west-to-east through the stars (prograde motion), but peridiocally, the motion changes and they move east-to-west through the stars (retrograde motion): The retrograde motion continues for a short time and then the motion switches back to prograde. Notice how Mars seems from Earth to travel in a loop. “It just appears to do so because of the relative positions of the planet and Earth and how they are moving around the Sun.” Graphic showing the retrograde motion of Mars. One key observation: as a planet undergoes retrograde motion (drifts westward with respect to the stars), it becomes brighter. “It is not REAL in that the planet does not physically start moving backwards in its orbit,” NASA states.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |