This article explains the leap second - why it is needed and what difference a second can make!

We have all
heard of a leap year - that extra day added to the calendar every four years.
It may give us a longer February but it is also essential in keeping our
calendars and seasons accurate. If the extra day is not added to a leap year
then eventually (admittedly after over a century) the Winter will begin in July
and the summer will start around Christmas (and vice ? versa in the southern
hemisphere) because the Earth takes an extra six hours longer than the 365 days
of a year to circle the sun.

This article explains the world’s global timescale - UTC (Coordinated Universal Time)  what it is, why it was adopted and how important it is now.

What time is it? One of the commonest questions uttered
around the World but what exactly are we asking? You ask someone in China what
the time is then you will certainly get a different answer if you ask an
American, obviously their time-zones are on the opposite side of the world. 

But what if you ask two people in the same room as you? You
may get the same answer from them both but then again one person’s watch may be
a minute or two faster.