We Just Had a Leap Second

You probably didn’t notice unless you heard about this beforehand, but we just had a leap second a few hours ago. Similar to adding an extra day to leap years to keep the calendar in sync with Earth’s revolution around the sun, leap seconds must also be added once in a while. Our clocks are actually much more precise than daily and yearly cycles due to Earth’s motion, so we need to keep correcting things if we want, for example, January 1st to stay in winter in the northern hemisphere or if we want noon to be when the sun is near its highest point in the sky. One of the dangers that people always point out is that changing the clocks can wreak havoc with computer systems, which are used to very consistent, precise timing information. This is especially problematic for leap seconds since they aren’t added on a regular cycle as with leap years