On these days the Earth will be measurably—and, so far, unaccountably— accelerating its rotation, shaving from 1.3 to 1.5 milliseconds off of the usual 24 hours the typical day gets. A millisecond, or one thousandth of a second, is admittedly not much ...

Scientists anticipate that Earth's rotation will quicken enough to create three shorter days between July and August, starting Wednesday, July 9.

As for when this three-day event will happen, there are three days this summer when the moon will be around its furthest distance from Earth’s equator, resulting in the slight increase in Earth’s rotational speed. Scientists are predicting that this will happen on July 9, July 22 and Aug. 5.