On Saturday, June 30, a leap second tacked onto the day. In keeping up with the Co-ordinated Universal Time, 61 seconds instead of 60 were added at the end of the day on Saturday. A leap second needs to be added on because tides are causing a breaking action on the earth at 1.4 milliseconds per day per century, Cnet reported.
By making the last minute of June 30 an extra second longer, it's our way of keeping our atomic clocks in line. This has been calculated by the US Naval Observatory in Washington D.C. The last leap second adjustment was in 2008. It's a way of maintaining time with the continuous rotation of the earth. IBN Live reported that if no adjustments to time were made every so often over several years time, the sun would actually set at midday. Tides are another factor that determined when leap seconds should be adjusted for. It has the same purpose as adding an extra day in a leap year.