Galileo Galilei: 3 ideas and puzzles worth knowing

3 ideas and puzzles from Galileo Galilei, each explained in a minute and credited to the original work. Free on Savvy.

Four points of light beside Jupiter proved not everything in the sky orbits Earth
In January 1610, Galileo pointed a homemade telescope at Jupiter and noticed four small 'stars' that changed position every night, always lined up with the planet. He realized they…
— Galileo Galilei, Sidereus Nuncius (The Starry Messenger)
The Grand Duke's Dice Dilemma
The Grand Duke of Tuscany noticed something odd at the gaming tables: rolling three dice and adding them up, a total of 10 turns up more often than a total of 9 — even though there…
— Galileo Galilei, Sopra le Scoperte dei Dadi (Concerning an Investigation on Dice)
Galileo noticed there seem to be as many perfect squares as there are whole numbers
Every whole number (1, 2, 3...) can be paired with exactly one perfect square (1, 4, 9...) by squaring it, and every perfect square pairs back to exactly one whole number by taking…
— Galileo Galilei, Two New Sciences

Five ideas worth knowing, every week