It will happen again in 3007, 4007, 5007, 6007, etc. Dah!…

maybe i’m old but my favorite was
12:34:56 7/8/90

My Seiko 5 self-winding watch is usually within 5 minutes or so if I remembered to set it.  ‘Spoze I could drop it off at the jewellers to be regulated.  But hey, I’m not timing a moon launch.

Hmmm.

My wife told me I was a bit anal because I like to set my watch to the second, which is fine for my battery powered quartz regulated wrist watch, but a bit of a bugger for the spring powered mechanical pocket watch she bought for the wedding- its not finely engineered enough and tends to be +/- 15 seconds.

(warning- for sundial freaks only)

The accuracy of a sun dial changes through the year- If you plot minutes ahead/behind on a graph (x=date) you get a nice wave effect.

Depends on the sundial.  A sundial with an analemmatic scale, that is, one that has that wave built in, can be as accurate as you are capable of reading it, barring minor atmospheric and even more minor relativistic effects.

The analemmatic scale is of course necessary because the Earth orbits the Sun elliptically, not circularly.  The problem with the analemmatic sundial is that it is only theoretically accurate at the point in time it was reckoned for, and gets gradually less accurate as the precession of the equinoxes proceeds.  This precession also continually changes the time of year that particular constellations rise and set, and is responsible for lots of woo (this is the dawning of the Age of Aquarius, etc.)

Right now, we’re closest to the Sun in early January, and the length of the day plus night, say from sunrise to next sunrise, is longer than in July.  That’s because we move faster in our orbit when we’re closer to the Sun, and since we’re moving around the Sun in the same direction as we’re rotating on our axis, that extends the length of the day (plus night).  It’s easy to understand why this is so if you imagine the Earth not rotating on its axis but still going around the Sun- one orbit, one year, would make the Sun rise and set once, but in the other direction (west to east).  The Earth actually rotates on its axis about 366 1/4 times a year, not 365 1/4, but the orbit around the Sun subtracts one day each year.  And the orbit delays the Sun in the sky a bigger part of that day in January than in July (currently), because we move faster and thus further around the orbit then.

The time of year when we’re closest to the Sun is changing constantly because of the precession of the equinoxes.  However, since one complete precession takes about 26,000 years, today’s analemma is actually pretty accurate for tomorrow too, if you’re not fussy about nanoseconds.

So when you build your sundials, don’t carve the analemma in stone, but go ahead and pencil it in.

1) A horizontal gnomon is of no use if you live at the North or South Pole.

I’ll make sure I remember that on one of my frequent trips there.

The accuracy of a sun dial changes through the year- If you plot minutes ahead/behind on a graph (x=date) you get a nice wave effect.

maybe it’s an advantage to have shorter hours in winter.

Bit of a bugger for those games which are timed though (football/rugby/etc)

Timed/dated 10110:10010 01000/00101/00111

Sorry for the triple dip.  But the last post was not very exact, and I don’t want to be responsible for people making faulty sundials, getting to work late, and losing their jobs.

1) A horizontal gnomon is of no use if you live at the North or South Pole.

2) A vertical sundial face (with the horizontal gnomon pointing North or South) is only good for half the year if you live at the Equator.

3) It’s of course only the daylight hours that are shorter, in the Roman/Egyptian scheme, in the winter.  The nighttime hours are longer in the winter. Duh.

Go for the original Egyptian/Roman Hours. Each one was 1/12 of a day, and then 1/12 of a night.

These are of course the hours you get with a horizontal gnomon on your sundial. If you want hours that are (close to) equal, winter and summer, you need a gnomon pointing to the celestial pole, which the Romans and Egyptians didn’t figure out.  But as you say, Hussar, maybe it’s an advantage to have shorter hours in winter.

Okay, elwed, you’ve pinned me down.  How about “10100 before 1010”?

Go for the original Egyptian/Roman Hours. Each one was 1/12 of a day, and then 1/12 of a night.  This means 9-5 is much easier in the winter.