December 31 2016 Leap Second

On New Year's Eve an extra second will be added to the end of the day. This extra second is called a leap second. As I'll explain later, leap seconds need to be added periodically to bring the time we measure with accurate atomic clocks in line with the natural time which results from the rotation of the… Continue reading December 31 2016 Leap Second

The long summer evenings

This post talks about two interesting effects to do with the way it get dark after the Sun has set.  The first one, which anyone who has travelled to places lying at different latitudes will have seen, is that the closer you are to the equator the quicker it gets dark after the Sun has… Continue reading The long summer evenings

Easter – 27 March 2016

This year, for the majority of Christians, 27 March will be Easter Sunday, one of the most of the most important dates in the Christian calendar. Although Easter is a is a festival celebrating the resurrection of Jesus Christ from the dead, it is also widely marked by non-Christians in the UK, particularly as there are two very welcome public… Continue reading Easter – 27 March 2016

The first day of spring

Now that we are in the month of March, for most of us in the northern hemisphere the worst of the winter is over, and it is only a couple of weeks until 21 March, the first day of spring. 21 March is an important date for other reasons, too. For one thing, it is used as the basis for the… Continue reading The first day of spring

The evenings are drawing out already

As I complete this post, it's completely dark outside and it's only 5 o'clock in the afternoon. Today is 14 December, and most people I come across think that it will continue to get dark earlier and earlier in the afternoons until 21 December, the shortest day of the year (at least for those of us… Continue reading The evenings are drawing out already

September 18 The Shortest Day

Revised 10 September 2018 Most people are probably unaware of this but the length of a solar day, which is the natural day measured by the rising and setting of the Sun isn't  always 24 hours. It varies slightly throughout the course of the year and that September 18 is in fact the shortest solar day in the year. This post… Continue reading September 18 The Shortest Day

Jun 30 2015 – Leap Second

On June 30 2015 an extra second will be inserted into the very end of the day. This extra second is called a leap second.   Why do we need leap seconds? Although we take the average length of a day to be 24 hours, the mean solar day, or average "natural" day measured by the… Continue reading Jun 30 2015 – Leap Second