Scientists are pretty fussy about time. At the end of 2016, the folks at Goddard Space Flight Center in Maryland added an extra second to the year. So if you felt that year dragged on a bit longer than normal, you were right.

Why did they do that? Because the rotation of the earth slows down over time, the years get just a tiny bit longer. When scientists track manmade objects launched into space, they must have accuracy down to the millisecond. This is “to make sure our collision avoidance programs are accurate,” according to one scientist.

For most of us, a…