Every time you shuffle a deck of cards, you produce a configuration that has almost certainly never existed before, and never will again. But how do you know when you’ve shuffled enough times to mix up the deck? https://t.co/1vP6F5h8my

The asteroid Ryugu, visited by the Hayabusa2 spacecraft in 2018, contained water similar to the most common kind found on Earth. Asteroids are one possible vehicle for water’s arrival on the planet. https://t.co/Dgjme1chwF