If observed from one night to the next, a planet appears to move from West to East against the background stars most of the time. Occasionally, however, the planet's motion will appear to reverse direction, and the planet will, for a short time, move from East to West against the background constellations. This reversal is known as retrograde motion.
If observed from one night to the next, a planet appears to move from West to East against the background stars most of the time. Occasionally, however, the planet's motion will appear to reverse direction, and the planet will, for a short time, move from East to West against the background constellations. This reversal is known as retrograde motion.
Ptolemy did something truly amazing. He developed a way of accounting for retrograde motion built on the idea that some planets orbit the earth not in simple 'circles' (his model is built on circular orbits and not eliptical orbits), but along circular orbits the center of which would mark out a circular orbit around earth. This is hard to follow; see the animated demonstration at the link below. He believed that it was the task of astronomy to define the movements of all the 'wandering' stars [planets] using nothing but circles. He incorporated some other ingenius mechanisms, like having the earth move away from the center of a planet's orbit, to account for the speeding up and slowing down of the planets in their orbits.
The amazing part is that the model worked so well [in terms of location, not distance] that the mechanics of some planetariums is based upon it.
This is a stunning example showing that even the most brilliant people can be convinced that a model must reflect reality because there is tight correspondence, or correlation, between the model and field observations. It also demonstrates that inductive reasoning, while important, cannot be relied upon to have the strength of properly applied deduction. For that matter, even what we convince ourselves to be deduction can reveal an inductive weakness now and then.
By epicycles, small circular "side loops" on the main circular orbit.
The planets moved along small circles that moved on larger circles around the Earth.
Prograde motion is a counter-clockwise motion or west to east, retrograde motion is clockwise motion or east to west.
The heat death of the universe is a suggested fate of the universe, its final thermodynamic state in which it has diminished to a state of no thermodynamic free energy to sustain motion or life.
Motion is a fundamental property of the universe, nothing is at absolute rest.
what was isaac newtons accomplsihments.? what was isaac newtons accomplsihments.?
newton's first law of motion is also known as LAW OF INERTIA. inertia is the property of a body by which every body if is in rest it tends to remain in rest and if in motion it tends to remain in motion.
If observed from one night to the next, a planet appears to move from West to East against the background stars most of the time. Occasionally, however, the planet's motion will appear to reverse direction, and the planet will, for a short time, move from East to West against the background constellations. This reversal is known as retrograde motion.
retrograde motion
Retrograde motion important in astronomy because it helped to explain that the planets revolved around the Sun. Retrograde motion is the ability of some objects to rotate in a direction that is opposite what is expected.
retrograde motion
Earths faster motion makes Mars appear to be going backwards, the backwards motion, in fact, is what caused retrograde motion. --Ptloemy used Epicycles to explain how geocentrical models worked.
retrograde motion
All the models explain retrograde motion because it is such an obvious phenomenon. In Copernicus's model an outer planet goes into retrograde motion when the inner planet overtakes it so that it appears from the inner planet to be going backwards along the ecliptic.
Retrograde motion is motion in the opposite direction. In the case of celestial bodies, such motion may be real, defined by the inherent rotation or orbit of the body, or apparent, as seen in the skies from Earth.
It offered more natural explanation for the apparent retrograde motion of planets in our sky.
He created a model for the universe that explained retrograde motion if Earth was at the centre.
It was a more elegant explanation of retrograde motion.
This is nothing as complicated as "models of the universe"... it is a geometric phenomenon. For example, if an outer planet - outside the Earth's orbit - is retrograde, that simply means that Earth is overtaking that planet; temporary the planet seems to go "backwards".The main movement of planets is from West to East; but for part of each orbit, each planet will have an (apparent) movement from East to West - then it is said to be "retrograde".