Most recent change of Horizon

Edit made on January 29, 2009 by DerekCouzens at 17:10:42

Deleted text in red / Inserted text in green

WW
The !* Horizon !* is that imaginary line on the Earth's surface
that marks the furthest point that can be seen from your
vantage point. The exact distance to the horizon depends on
your altitude, and increases as you get higher. That's why
the lookout on a ship was always posted at the highest point
on the ship.

The *exact* values depend, or course, on the local topography,
but we usually get close enough simply by assuming the Earth
is a sphere. We need to know the size of the Earth to do the sums.

Interestingly, the distance to the horizon calculation is
effectively identical to the calculation of orbital velocity.

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