Wanted to show that God had created the heavenly bodies according to a regular, beautiful, symmetric design. Went through the observations of Tycho Brahe, postulated an increasing number of circles in Mars' orbit, until he had got it down – but it was a complicated theory. There were small errors ascribable to measurement, and thankfully Kepler did not want to believe that Brahe had measured imperfectly, so he kept working until in desperation he postulated an elliptical orbit. This fit perfectly!

Before, everyone assumed the orbits were circles – even if you had to give the planets many different circular orbits they could be in at different times. Shaping it as an ellipse enabled there to be only one orbit. But few people took such a thing as an elliptical orbit seriously – it seemed too imperfect for heavenly bodies.

He explained the elliptical orbit to Galileo himself, who rejected it. Now we accept it as Kepler's First Law.

• Kepler's First Law: The orbit of any planet is elliptical. They can be almost circular, but never perfectly circular.
• Kepler's Second Law: planets move fastest when they are closest to the sun, and slower when far away.
• Kepler's Third Law: The time for an orbit increases the further the planet is from the sun.

Famous for cryptic and paradoxical utterances. Exalted the logos as a cosmic power and identified fire as the primal substance, whereas Thales of Miletus had identified water. Later, Empedocles (490–430 BCE) subsumed both views.

A famous statistics blogger (statmodeling.stat.columbia.edu/) who tries to make political science and statistics more accessible to journalists and to the public. Co-blogger of The Monkey Cage. A cool book: Teaching Statistics: A Bag of Tricks.

Andrew Gelman was born in 1965.

A probable genetic freak, due to a too-fast mind for math. Helped in the childhood of computer science, came up with pseudorandom number generators – a way to get a deterministically operated electric system (such as a computer) to output a random number, which is not as easy as it sounds.

Many things are named after von Neumann. For example, the idea of self-replicating machines that explore space, "Von Neumann probes". If alien civilizations exist, they may have launched one or more waves of such machines each, and what happens when they meet? Natural selection implies that the most ruthless machines would survive, which then implies (assuming there are many civilizations in the universe) that there's a sphere of von Neumann probes somewhere out there, expanding in all directions, eating all the planets and stars in their wake (to build more of themselves), potentially travelling near the speed of light so that we won't see them until they're already here.

After Stanislaw Ulam invented the modern version of Markov chain Monte Carlo, von Neumann immediately understood its importance and programmed the ENIAC to carry out Monte Carlo calculations (not MCMC?).