Another New Year

So here we are another year has come around and it is 2014. When exactly did the New Year start?
We celebrate the start of the New Year at midnight when the date changes, but that is a moving target, being at different times around the world. Large territories are artificially put into time zones, so that in some places, you can celebrate New Year, walk a few yards and an hour later celebrate it all over again. Why do we herald in the New Year at night? Traditionally we measure a day by taking the time from when the sun is highest in the sky and measuring the hours until it reaches the highest point at noon the next day, showing the world rotates once every 24 hours. Curiously if you measure the time at night, midnight to midnight looking at a fixed star in the absence of the sun, you find midnights recur at intervals a little less than 24 hours apart. This is a real effect and is known as sidereal time. It is useful to astronomers but no one else as far as I know.

Many New Years ago I was a technician in a radio astronomy research station and we had several clocks on the wall, one set to GMT, one to East Coast USA time and one to sidereal time. We were working with Florida University, hence the USA time and we were astronomers, who mostly work at night. On that project, we were listening to Jupiter which broadcasts radio signals that sound like surf on gravel.   Follow the link to hear the sounds.  No one knew why then but it turned out Jupiter has a magnetic field and as the inner moons orbit, they generate these signals in their upper atmosphere.

Anyway I digress, here it is 2014 and another year is started and we all agree it started at midnight on the last day of December. This was not always the case, the old year ended on the last day of May and April the first used to be the first day of the new year, but this was changed some time ago. However, accountants and bankers do not seem to have caught that news and continue to start their financial year on April fool’s day. I suppose they call it April fool’s day since they all get a whopping bonus every year from our money. Once upon a time, knowing the exact time was not so important and everyone set their clock by looking at the sun and calling it midday when the shadows were shortest. In England this was never a problem, even though in the far west of Cornwall, they were setting their clocks about ten minutes later than those folks living in East Essex. It really did not matter, but as transport got faster and trains became able to traverse the country in less than a day, time tables had to be adhered to. If they were not using a standard ‘railway’ time, the eastbound train was going to collide with the westbound train because they would not be at the passing place at the right time. To make sure this never happened, well not too often anyway, the whole country started to use the same time as London. So now we all agree when midnight is and we all celebrate the New Year at the same time in the UK. Mind you, if you are not a night person, you could celebrate at any convenient time, by finding the right foreign radio or TV program on the Internet and go to bed an hour or maybe two hours early. Always useful if you are one of those unfortunates who have to work on New Year’s Day.  So a happy 2014 to you all and happy blogging.

PS if you are still wondering how sidereal time works, see if you can follow this diagram.

 Because we are moving around the sun day to day it is a little further around before it get overhead. The star at midnight still appears to be in the same direction because it is so far away the change in position over one day is infinitesimally small.