[Ti] tomorrow's MacWorld

[Bob Jacobsen]

At 4:01 PM +0100 1/7/03, Trevor J. Hutley wrote:
>Is UTC some politically-correct new-fangled modern unknown-to-me 
>acronym to replace GMT ?

UTC is "every second is exactly the same length"; GMT is "on average, 
noon is the time the sun is at it's highest angle in Greenwich 
England".  Because the speed of the earth's rotation changes slightly 
over the years, these vary with respect to each other.  When the 
difference gets to be more than 0.7 second, the difference is 
adjusted by the insertion of "leap seconds".

So if you want to use precise time intervals, you use UTC.  And if 
you're doing celestial navigation, you use GMT.  And if you're doing 
anything else, you don't really need to care.

Bob
-- 
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Bob Jacobsen (Bob_Jacobsen at lbl.gov, 510-486-7355, fax 510-495-2957)