gordon.dewis.ca - Random musings from Gordon


Falling back in time

November 05, 2010 @ 14:44 By: gordon Category: Astronomy, Current affairs, General

800px-Vortex_backThis is the weekend that we fall back in time.

No, I’m not talking about travelling through the Time Vortex, though that would be cool. Rather, I’m talking about changing back to Standard Time.

Twice a year most parts of North America change their clocks to chase the sun. Most recently, the dates this happens were changed to be the second Sunday in March and the first Sunday in November by the US Energy Policy Act of 2005. This year, it happens at 2am on Sunday, November 7th, so you can safely sleep in this Sunday.

The main reason being touted in support of daylight saving time is that it will result in an overall reduction in energy consumption. I have yet to see anything that says this has been achieved to any degree. David Prerau’s book Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time (hardcover: 1560256559; softcover: 1560257962) tells the story of daylight saving time starting with when Benjamin Franklin mused about how many candles could be saved if the clocks were adjusted so that people were more in-sync with the sun up to just a few years ago. Worth a read if you have a chance.

If you’re a *NIX system administrator you probably updated your systems a couple of years ago, but in case you haven’t you probably should take a look at this. The zdump command should give you something like this:

[gordon@seedling]$ /usr/sbin/zdump -v /etc/localtime |grep 2010

/etc/localtime  Sun Mar 14 06:59:59 2010 UTC = Sun Mar 14 01:59:59 2010 EST isdst=0 gmtoff=-18000

/etc/localtime  Sun Mar 14 07:00:00 2010 UTC = Sun Mar 14 03:00:00 2010 EDT isdst=1 gmtoff=-14400

/etc/localtime  Sun Nov  7 05:59:59 2010 UTC = Sun Nov  7 01:59:59 2010 EDT isdst=1 gmtoff=-14400

/etc/localtime  Sun Nov  7 06:00:00 2010 UTC = Sun Nov  7 01:00:00 2010 EST isdst=0 gmtoff=-18000


  1. Tweets that mention gordon.dewis.ca | Falling back in time -- Topsy.com (November 07, 2010 @ 01:22)
  2. gordon.dewis.ca | Falling forward through time (December 17, 2011 @ 10:57)

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