Sunsets are getting later!

7:24 PM, Dec 20, 2011   |    comments
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PORTLAND, Maine (NEWS CENTER) -- Even though days are still getting shorter, sunsets are getting later.  The optimists among us believe that the long inexorable march toward spring has begun.

A number of factors contribute to the phenomenon says Paul Howell who is studying for his PhD in Astrophysics at Boston University. Among those are earth's slightly elliptical orbit and the fact that the earth doesn't revolve in exactly twenty-four hours.

"When our hemisphere is tilted toward the sun, the days are longer.  If you leave you oven on for a longer period of time, things get hotter and hotter," Howell told News Center. "The sun is also higher up in the sky, so it beats down on the ground more directly and that gives more energy to the earth.  We have more heating and the heating is more effective."

Another fact is that the earth is orbiting the sun as it revolves.  It needs to make slightly more than one revolution to exactly face the sun once again because it has moved along its orbital track.  This change of location means sunrise and sunset move back by just a few seconds.  Since the difference in the length of day is so minimum, it seems that the sun is rising and setting later in the day.

The winter solstice is Thursday morning at 12:30 A. M. EST.  Thursday will be two seconds longer than Wednesday.  Friday will be four seconds longer than Thursday.  Saturday will be nine seconds longer than Friday. By the spring solstice, the days are increasing in length by three minutes.

In Maine, there is significant disparity in sunset, depending on where you are.  In Portland, the sun is setting at 4:07 P. M.  In Presque Isle it is setting at 3:46 P. M. Portland's days are currently eight hours and fifty-five minutes.  Presque Isle's are eight hours and thirty-three minutes.

In the summer, it is just the opposite.  On June 21, the sun will rise in Portland at 4:59 A. M. and set at 8:26 P. M.  In Presque Isle, the sun will rise at 4:38 A. M. and set at 8:30 P. M. That means Portland's longest day is fifteen hours and twenty-seven minutes in length and Presque Isle's is fifteen hours and fifty two minutes in length.


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