vincent p. norris wrote:
If you mean celestial navigation, there isn't much point in private
pilots learning that, unless it's just to satisfy their intellectual
curiosity. Celestial nav requires expensive equipment and intensive
training; and in any case is virtually impossible to carry out while
flying a private aircraft.

The equipment isn't really that expensive. You can buy a reconditioned
aviation sextant for $990
(http://www.celestaire.com/catalog/products/1502.html), and perfectly good
brand new marine one for about $400 ($1,000 for a top-of-the-line model).
You'll need a "chronometer" (which these days means a $10 digital watch)
and some books of astronomical tables (or, more likely these days, a
program for your calculator or laptop).

There is certainly an investment in training (probably 20 hours of
classroom time). The biggest problem is that any aircraft most of us are
ever likely to get access to won't have an observation port. For $5.4
Million, however, you could get yourself a T-43A
(http://www.fas.org/man/dod-101/sys/ac/t-43.htm) and go to town. Flight
crew not included.

I understand even the Naval Academy no longer teaches celestial nav,
which does kinda sadden me, if only for nostalgic reasons.

I agree with Vincent. Celestial nav is cool, but just isn't useful any
more. It's an interesting thing to learn, but only any practical value is
long since gone. GPS drove the last nail in the celestial coffin 10 years
ago.