How did people in ancient times explain the motion of the planets?

Answer 1

People in ancient times were more aware of the movements of the stars and planets than we are today. They used the positions of stars to predict the times of the year when they needed to plant crops, (eg. in Egypt, when the Nile was going to flood) and other important times of the year.

As they were very proficient at this, they noticed that there were some "stars" that wandered around the sky and did not follow all the other stars in moving on an annular basis. They called these "stars" planets (meaning wanderers) and these became the basis for their gods and mythologies. As these planets were gods, they were not bound by the rules of the sky and it was believed they could move under their own will.

It wasn't until the heliocentric system was proposed that scientists could make proper sense of this planetary motion.

Answer 2

Epicycles.
In ancient times the geocentric universe was the dominant theory but those pesky "wandering stars", the planets, wouldn´t behave. Sometimes they seemed to be moving backwards, impossible if everything revolved around the earth in neat circular orbits. So the ancient greeks, namely Ptolemy, invented the epicycle, another circle around which the planets would orbit around their own orbit, the deferent, as if an unseen object was pulling the planet, slinging it around in circles while they both orbited the earth. But of course there is no such object that could excert that force on the planet (the Moon would be orbiting the Sun in an epicycle if Earth was invisible). The geocentric model was wrong and so too the idea of epicycles. Still Ptolemy´s geocentric cosmology remained the dominant theory for 1000 years...

Answer 3

Remember that stars change their position in sky during the year, they did some kind of assumptions first, I think that was on Greek times.
Later they used things like telescopes which helped to deem some values like mass or dimensions, that was Galileo's time. Later, Johannes Kepler used these values and discovered that planet's trajectory was elliptical and Newton introduced the Universal Law of Gravitation, joining those facts helped to understand the motion of planets. That was 4 or 5 centuries ago

Answer 4

People in the ancient times believed that the universe was geocentric, in other words, the sun and all the other stars revolved around earth, with earth being the center of the universe.
This began to be gradually replaced by Copernicus's heliocentric model in the beginning of the 16th century.

Answer 5

If I recall correctly, the ancient Greeks believed that the earth was surrounded by concentric transparent spheres. On these spheres were fixed the sun, moon, stars, and each planet (that they observed, so the naked-eye visible ones) had its own sphere. This is how they explained them moving differently than the rest of the stars.

Answer 6

In "ancient" times telescopes did not exist so most planets went unknown for a while. General thought was, until around Galileo's time, that the Sun, Moon, and stars revolved around the Earth as a part of God's divine plan.

Answer 7

During the time of Copernicus, or before ?