(2006) Explorations: An Introduction to Astronomy, Fourth Edition, The McGraw-Hill Companies, Inc. In the next section we will look at Kepler's Laws!Īrny, Thomas T. However, within a century more support such as Kepler's laws were adding credibility to this theory. This theory was not initially accepted by the scientific community. This is a much better explanation for retrograde motion because the inner planets move faster than the outer planets. In 1543 he proposed that the Sun was in the center of the solar system and earth and the other planets revolved around it. Nicolaus Copernicus was the first to suggest the heliocentric view of the solar system. Here is an animation that demonstrates this. The pictures were taken at two week intervals for almost a whole year.Īnimation: Heliocentric Epicycle Model of Solar System Before the heliocentric (sun centered) view of the solar system was widely accepted, some people believed that epicycles could explain retrograde motion. Why is this evidence for a heliocentric model of the universe?Īnimation: Retrograde Motion This animation explains why we see other planets experiencing retrograde motion.Īnimated PhotoThis set of photographs shows the retrograde motion of Jupiter and Saturn. It is easier to see than explain so click on the following links and answer these questions: Retrograde motion is when a planet starts moving in the opposite direction. To clarify, the normal direction of Planets from our perspective is west to east. Retrograde motion is the apparent backward motion of a planet viewed from Earth. However, one thing the geocentric model did not explain very well was retrograde motion. At first, they move away, then as you pass them, they APPEAR to be moving backward relative to you - even though they are still walking forward.The Solar System was once thought to be Earth Centered. Watch your friend and think about how they are moving relative to you. Start out standing side by side with a friend. You can experience this effect for yourself. So as we catch up to that planet in its orbit and then move beyond it, the motion appears to go through the pro-retro-pro cycle. Notice that it is all due to the fact that the Earth moves faster in its orbit than does Mars. This animation shows the apparent motion of Mars during one of its recurrent retrograde motion periods: in this case, during August and September of 2003. How the planet Mars would appear to have both prograde then retrograde then prograde motion is shown in the diagram below. The explanation for retrograde motion in a heliocentric model is that retrograde occurs roughly when a faster moving planet catches up to and passes a slower moving planet. This seemingly strange behavior is easily understood within the context of a Sun-centered ( heliocentric) solar system. The retrograde motion continues for a short time and then the motion switches back to prograde. However, peridiocally the motion changes and they move east-to-west through the stars. These images show the apparent pattern made by the planet Mars while in retrograde motion during 2014(left) and 2016(right) over Pasadena. Normally, the planets move west-to-east through the stars at night. It just appears to do so because of the relative positions of the planet and Earth and how they are moving around the Sun. It is not REAL in that the planet does not physically start moving backwards in its orbit. Retrograde motion is an APPARENT change in the movement of the planet through the sky. What does it mean for Mercury to be in retrograde? What does it mean for Mercury to be in retrograde? StarChild Question of the Month for June 2002 Question:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |