re: Kepler and Mars
For centuries, those who observed the sky wondered how come the planet called Mars seemed much more brilliant during opposition one year, than 26 months later during the following opposition.
Perhaps it was because...no, it's not possible, planets turn in perfect circles around the Earth...yet, why is Mars so much more brillaint?
Kepler came up with the idea that Mars had to be closer than the last time or the next time, so the orbit wasn't a circle but an ellipse.
And thus his laws..
What Mars brought to our perception of the universe! A milestone!
Raoul