Time Zones are Wild

I noticed last night that the sun in Keene, NH where I’m staying seemed to go down much earlier than I expected for early days of summer. It turns out that I was right: sunset last night was 8:32 p.m.

Back in Charlottetown it didn’t set until 9:09 p.m.. And even up at my parents’ place, which is in the same time zone as Keene and seems “close,” there was an extra 30 minutes of daylight as the sun set at 9:05 p.m..

Go even further east and they get even less of an evening: in Cape Cod the sun set at 8:20 p.m.

Go north and west to the western extremes of eastern time in Thunder Bay and the sun set at 10:03 p.m.

Amazing.

Comments

paul beard's picture
paul beard on June 26, 2007 - 16:40

Isn’t this more to do with latitude than longitude? I don’t know where all these places are but I do know that Charlottetown is north of Keene and I would expect the days in Keene to be shorter.

Andrew MacPherson's picture
Andrew MacPherson on June 26, 2007 - 19:27

Defitely lattitude is a factor for TB as well. I have wonderful summer solstice memories of summers in Cold Lake, Alberta where the sun seemed to skim the horizon for several hours. The winter solstice was another story….

Peter Rukavina's picture
Peter Rukavina on June 27, 2007 - 22:46

It helps to be working this week in the middle of the smartest minds on the country on the lay astronomy front: I have learned that the line that “connects” all the places sharing the same sunset time is called the Terminator. With this new information in hand I learned a very neat fact from Wikipedia:


On the spring and fall equinoxes (around March and September 21), there is no tilt of the earth with respect to the sun so the terminator line is parallel with the axis of the earth and with the lines of longitude.
oliver's picture
oliver on June 29, 2007 - 06:40

No tilt of the earth with respect to the sun” is cryptic and risks misleading. Earth’s axis is always tilted and never perpendicular to the plane in which Earth orbits the sun (the tilt angle is called the obliquity of the ecliptic and it’s 23 degrees plus a bit everywhere and for the rest of your life). The solstices happen when Earth’s tilt is oriented directly toward or away from the sun, or to put it another way, at a right angle to Earth’s path in orbit. The equinoxes are when the Earth is leaning perfectly forward or backward, which is why all latitudes get exactly 12 hours of daylight on those days (it’s obvious, if you can picture it). The quote is saying “none of the tilt of the earth” or “no component of Earth’s tilt” is in the direction of the sun.

oliver's picture
oliver on June 29, 2007 - 06:41

i.e. “forward or backward” along it’s orbital path.

oliver's picture
oliver on June 29, 2007 - 06:50

Also “the terminator line is parallel with the axis of the earth and with the lines of longitude” is a long and weird way of saying “the terminator line is a meridian.”

oliver's picture
oliver on June 29, 2007 - 18:08

P, you ought to read “Longitude” by Dava Sobel, if you haven’t.

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