Planet Earth will spin a little faster on three separate days this summer, starting today. This will technically result in shorter days, but the change will be so minuscule you won’t even notice.

Aren’t the summer days supposed to be longer and the winter days shorter? Since when have things gone in reverse for the summertime? Since now, maybe? Starting today? Okay, here’s what’s going on.

Earth’s spin is not as steady as it looks from the ground. As ice sheets melt and aquifers are drained, scientists now say the planet’s axis has shifted by more than 30 inches, a subtle but measurable ...