Science desk
< January 19	<< Dec \| January \| Feb >>	January 21 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

January 20

Astronomy Question

The First and the Last Noon of the solar year don’t coincide. This means solar noon lags 24 hours, which appears in what we call leap year. Although we update our calendar every after 4 years for our own conveniences, however, it doesn’t mean an earth also adjust its axial and orbital motion for the sake of our calendar. This small change reverses days into nights and seasons as well (summer into winter after 720 years approx.) over time, if the real position of the earth is observed in its orbit around the sun instead of adding Feb 29 in leap years. Your comments, please. 50.66.1.32 (talk) 19:54, 20 January 2018 (UTC)EEK[reply]

This user's edit at Talk:Season#Earth’s Rotation and its Orbital Motion may be useful in determining their misunderstanding. -- ToE 20:59, 20 January 2018 (UTC)[reply]

We adjust our clocks and calendar to match the observed rotation of the earth. Much calculation over the centuries has ensured that our day and year never deviate far from the norm. If we are still around to observe, the day length (via leap seconds or hours) and the calendar (via leap years) will be adjusted as required over the next few thousand years to closely match the exact periods of rotation. Dbfirs 21:49, 20 January 2018 (UTC)[reply]

I sort of doubt that prediction, actually. Leap seconds were a mistake from the start. They cause continuing annoyances in the computer age because they make it impossible to match a civil time in the future with a timestamp based on count of seconds. They were never necessary; the drift in (say) the civil time of sunset is slow enough that no one would be disturbed by it over the course of even a long life.

My counter-prediction is that leap seconds will eventually be dumped in favor of some version of TAI or GPS time, possibly with a constant offset to avoid a discontinuity at the time of changeover. There have been several attempts to do this; the last one, if I recall correctly, didn't miss by much. There's a lot of resistance to such a change, of course, but hopefully it will eventually happen. --Trovatore (talk) 21:59, 20 January 2018 (UTC)[reply]

I was looking ahead to a possible further slowing in the axial rotation (not that I'm predicting it -- we just don't know). If leap seconds are abandoned then the alternative is an eventual leap hour that I mentioned above. This would easily be implemented by those countries who have summer time or daylight saving time. We seldom notice that the sun is not exactly overhead when we expect it to be, but eventually an adjustment might be needed to avoid hot sun at midnight. I suppose, by the time it is needed, we might have the technology to speed up the rotation of the earth to match atomic time. Dbfirs 08:51, 21 January 2018 (UTC)[reply]

I'd recommend the original poster to read about the Sothic year and Analemma. --93.136.126.95 (talk) 19:19, 21 January 2018 (UTC)[reply]