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I have been wondering why the sun sets at a later time after December 21, but the sunrise does not occur at an earlier time until days later. It seems like the sun would start rising earlier the same day it begins to set later. Can you shed some "light" on this?
Rob
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What a great time for any sort of sun type query. Monday March 20th marks the Vernal Equinox, a time when spring begins on our calendars and we have 12 hours of daylight and 12 hours of night.
I hope I can tackle some of these astronomy questions, I won't lie to you, I'm into weather, not so much outerspace but at the very least, we can look at some other links to help us understand all of this better.
Rob asks about the winter solstice on the 21st of December. This day marks the shortest of the year and from that point on the days begin to get longer. If we visit the US Naval Observatory page to figure out what time the sun sets and rises on December 21st in Salt Lake, we'll find that the sunrise time is 7:48 am and the sunset time is at 5:03 pm.
Basically, why isn't the earliest sunset on the shortest day of the year?
The big part of this is that our clocks are synchronized with the "mean solar day". This assumes that the tilt of the earth (obliquity) is zero and the orbit of the earth is circular, when actually, the earth is tilted at 23.5 degrees and the orbit of the earth is an ellipse or an oval type of path.
The main effect of the way our Earth is tilted and the ellipitcal path we take around the sun pushes our sunset start to become later before the solstice. Part of this has to do with the error between local noon (the sun in the center of the sky above us) and the clock's noon. I've put some links on the side to help out with this tricky question and I hope it helps. We can look at this again if this doesn't clear it up.
Answered by KSL Meteorologist Dina Freedman
