[time-nuts] FW: IIMorrow GPS units non-functional since Sunday
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:
> Don't tell me people still use miles? Nautical or otherwise?
> What's wrong with the good old kilometre?
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"
More information about the time-nuts