Sunday, November 07, 2010

#430 Changing Time

Last night we enjoyed an annual fall rite of passage.  We set our clocks back one hour.  We fell back.  By convention, we choose to apply the time change overnight so we get an extra hour of rest.  I suppose we'd all be even more confused if we turned the clocks back in the middle of the day when folks are up and about.

Changing time is all about the math.  We've divided the Earth into 360 degrees of longitude.  That means the earth must spin 15 degrees every hour to make a complete turn of 360 degrees every 24 hours.  At the equator, each degree of longitude spans about 70 miles, so time zones are about 1050 miles wide. 

Let's say you're traveling westbound around the world on a ship.  Every couple days you'd grab a bonus hour of sleep as you move your clock back at each time zone crossing.  But if you're eastbound, many 23-hour days you'd meet, setting your clock forward with each time zone crossing.

Yours in soon meeting 23-hour days head on,