Time and Time ZonesWhat a difference a day makes – twenty-four little hours. There are also twenty-four time zones. If there was only one, every part of the world would have a single time.

This is confusing as noon time can be when the sun is directly above you or when the sun is below the horizon and the moon instead is sighted on a dark night.

Actually a day is a little less than twenty-four hours. If we want to be correct and accurate, it is actually 23 hours 56 minutes and 4.1 seconds. This is a solar day which is the period the sun takes to reach its highest point in the sky consecutively.

For seafarers, a day may not be twenty-four hours but can stretch to forty-seven hours.

When a ship travels in an easterly direction and crosses the International Date Line, she would gain a day whilst she subtracts an hour.

Mathematically it would be 24+24–1=47

The longest day? The time difference between both sides of the International Date Line is not always exactly twenty-four hours because of local time zone variations. If you travelled around the world, changing time by one hour each time you entered a new time zone, then a complete circuit would mean that you had adjusted your watch by twenty-four hours. This would lead to a difference of one day between the date on your clock and the actual calendar date. If you cross the international date line moving in an easterly direction, you subtract a day (at midnight on a Sunday, instead of becoming Monday, it reverts to Saturday midnight), whereas if you are moving in a westerly direction you add a day (Saturday midnight becomes midnight on Sunday i.e. it becomes Monday 0000 hours).