Ides of May is Kepler Day (remember Kep on Monday 15th)

Kepler kept a diary and on 15 May 1618 he realized the first algebraic relation between distance and time (beyond simple proportionality) that I think anyone ever discovered.

it is simple and brilliant, now called his "third law".

In the most basic terms it says MULTIPLY THE DISTANCE BY ITS OWN SQUARE ROOT to get the orbit period.

so if some planet is FOUR times as far from sun as we are then (multiply 4 by the square root of 4 and get 8) it takes EIGHT years to go around

and if some planet is NINE times as far from sun as we are then (multiply 9 by the square root of 9 and get 27) it takes TWENTYSEVEN years to go around

Greeks knew about squares and cubes and areas and volumes and they watched the planets too, but they didnt realize this. Nobody on this planet, no human before Kepler, realized it. Great going Kepler!

In every galaxy there are possibly small green sentient beings who have realized this, they may have their own funny-looking Keplers. cheers to them as well.

He provided Newton something to start from.

to honor Kepler is not just about astronomy. It is about the beginnings of European science from out of the superstitious tailends of the Middle Ages.

KEPLER'S DAYJOB WAS TO CAST HOROSCOPES FOR RUDOLF THE HOLY ROMAN EMPEROR. They didn't have a job description called "scientist" in Northern Europe at the time. You scraped by doing theology or calculating people's horoscopes and things like that. They didn't know what a "scientist" was, and they certainly weren't going to pay you to be one.

So I put this announcement in General Science because it is about the beginnings of Science, not just Astronomy. He was a contemporary of Shakespeare. Francis Bacon was also a contemporary----he dreamed up the empirical method of getting knowledge by experiment and observation: that we now call the scientific method. Good idea Bacon! Great going to you too!