As the Earth rotates the length of the day varies and therefore a leap-second may be added or removed depending on the Earth's rotational changes.
A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1.
This implies that sometimes, but very rarely, a particular minute will contain exactly 59, 61, or 62 seconds.
See also: Leap Year (extra day), a year containing one extra day
Duration may then become negative
The important effect of leap second is that it may you got negative duration
- See the effect on Cloudfare
- See how google handle leap second Got a second? A leap second that is. Be ready for June 30th!