Rather poor BBC article on the proposal to abolish leap seconds.

The reporting seems to be awfully jingoistic (The Americans want to abolish Greenwich!! Man the beaches chaps!!) and incomplete.

I work in a field where Leap seconds are a minor annoyance but there are many areas where it's much more than that (GPS springs to mind). That said almost all systems that deal in high precision timing over extended periods of time must already be able to handle these adjustments.

This statement is totally bogus fill provided by the reporter:



What's worse is that it's tagged on to an actual quote from Dr. Robert Massey who makes the totally accurate statement that precision timekeeping is vital to Astronomy but says nothing about any effect abolishing the Leap Second would have on that (because there isn't any).

It said in the article that leap seconds have to be added every 18 months or so...due to the slowing of the Earth's rotation. That is .67 second every year.

This seems far too high for the slowing of the Earth's rotation. Running that backward 2000 years it means each day was 22 minutes shorter at 1 AD and almost 2 hours shorter 10,000 years ago, which is obviously not the case.

Could the cause of the leap second be due more to the precession of the Earth's axis rather than the actual slowing?

Not really.

The Leap Second is inserted occassionally to account for an accumulated difference, it does not imply that days from then on are all 1 second longer. The actual rate that the earth is slowing is approximately 1.4milliseconds per day per century. An Earth day was exactly 86400 seconds in length sometime around 1820. Since then the accumulated difference is ~2.1 milliseconds so a day now is ~86400.0021 seconds. If you add that up you find that time as measured in actual atomic seconds (and days of precisely 86400 seconds) drifts away from a time system that is based on a fixed point on the earth (ie a civil time such as GMT) by about a second or so every 18 months. The day is still only about 2.1ms longer though.

There's a really comprehensive explanation here courtesy

These really are caused by a slowing of the earth's rotation, precession does not change that.

It's all a bit relative though because days are not all the same length depending on your frame of reference (and Civil time uses the Sun as its basic frame of reference hence the Equation of Time analemmas and a whole bunch of other interesting stuff.

I rather wish we could abolish time zones and just use one uniform Earth time (which might as well be GMT). After all, 12:00 noon isn't exactly midday around here anyway, so what difference would it make if midday were defined as 0600 locally anyway? That way, if people want a technically exact clock-time, it can be the same everywhere, and if I want to know what the solar time is I can look at a sundial.

The article seems to suppose that there's something sacrosanct about the Greenwich meridian, though. Greenwich was actually a latecomer to the Prime Meridian business, not being generally adopted until 1884 and not universally adopted for another 30 years. If I'd been there, I'd have argued for keeping the classical standard of a Prime Meridian running through the farthest west island of the Canaries group (El Hierro -- about 18 degrees west of Greenwich) but it's rather too late now!