Tuesday June 30 is the day to adjust
your clocks back by one second. At 2359 Greenwich Mean Time on June
30, or 9.59am US EST on July 1, the world will experience a minute
that will last 61 seconds. It is called the leap second. That is
when timekeepers adjust high-precision clocks so they are in sync
with earth’s rotation, which is affected by the gravitational tug of
the sun and moon.
The last modification, on June 30, 2012 was disruptive for many
internet servers, including Qantas’ online reservation system, which
went down for several hours. The leap second is not something
that needs to be added to your watch, your stove, the clock on
your nightstand, etc.