> What does it mean to be like epicyles or like ellipses? Baaack in the day (hundreds of years ago) everyone thought the sun & planets went around the earth. A

> What does it mean to be like epicyles or like ellipses? Baaack in the day (hundreds of years ago) everyone thought the sun & planets went around the earth. And since Circle are Perfect (as lots of people thought), they must go around the earth in a circle. That's all nice and pleasing. However it doesn't match where you actually see the planets. The maths doesn't match what you see with your telescope! So people started doing complex "circles within circles" (epicircles) to try to get their maths to match reality. Instead Kepler came along and said "It's not cirlces, it's ellipses" (ovals). Turns out you only need one ellipse per planetery body. Then you get a nice simple mathematical models and it matches reality!