On second thought: Scientist want to make this unit of time more precise

One thousand one. One thousand two. One thousand three. We all know how long a second is — at least approximately.

But did you know that we rely on the element Cesium to officially measure this unit of time and that we're due for an update?

Here & Now's Celeste Headlee speaks about this with Elizabeth Donley, chief of the time and frequency division of the National Institute of Standards and Technology in Boulder, Colorado.