[time-nuts] FW: IIMorrow GPS units non-functional since Sunday

Jim Lux james.p.lux at jpl.nasa.gov
Wed Aug 20 09:56:16 EDT 2008

Quoting Jim Palfreyman <jim77742 at gmail.com>, on Tue 19 Aug 2008  
11:24:31 PM PDT:

> Wow.
> Don't tell me people still use miles? Nautical or otherwise?
> What's wrong with the good old kilometre?
> Jim

Simple...Britannia ruled the seas, while the Cassinis measured the  
earth.  Why the prime meridian is in Greenwich and we use meters for  

And, if you're navigating a boat, the fact that 1 minute of latitude  
is a nautical mile is fairly convenient.  If you know your current  
position, and that where you want to be, and you can approximate the  
cosine of your latitude, you can figure out distances to within a few  
percent in your head, making a plane earth assumption, which is  
probably reasonable for a day's run in most boats.

Do you want to try and navigate the Straits of Magellan or the local  
harbor this way.. probably not.  But, for getting from one port to the  
next, it's "good enough"

Jim Lux

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