Home > Ephemeris Program, Seasons > 12/09/2016 – Ephemeris – The earliest sunset

12/09/2016 – Ephemeris – The earliest sunset

December 9, 2016

Ephemeris for Friday, December 9th.  The Sun will rise at 8:08.  It’ll be up for 8 hours and 53 minutes, setting at 5:02.  The Moon, 2 days past first quarter, will set at 3:39 tomorrow morning.

In twelve days we will have the shortest day in terms of daylight hours.  But the change isn’t uniformly distributed in the morning and evening.  Tonight and tomorrow evening we will have the earliest sunsets  Sunset times have been within the same minute for the last few days and will continue for the next few.  The latest sunrise will occur on January second.  The reason is that the Sun is traveling faster eastward than average, so the Earth’s rotation takes a little longer each day to catch up with it. Near the solstice the Sun is at a higher latitude, where the longitude lines are closer together, also the Earth is nearing its closest to the Sun, so moves faster its orbit adding to the effect.  The effect exists in June but isn’t as noticeable.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.



This figure 8 is called an analemma. One can find it on old globes in the Pacific Ocean. Explanation below. Created using my LookingUp program by plotting the Sun at 7 day intervals at local noon for a year.

At the bottom of the analemma is where the Sun is near the winter solstice when it is moving its fastest eastward.  At the top, near the summer solstice the Sun is moving faster than average, but not as fast as it is now.  The Earth will be nearest the Sun on January 4th, a point called perihelion.  Aphelion next year, when the Earth is farthest from the Sun, will be July 3rd next year.

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