Astronomical coordinates

JRS: In article , dated Thu,
12 Jan 2006 23:30:50 local, seen in news:sci.astro, Jonathan Silverlight
posted :
In message , Dr John Stockton
writes

Since the Astronomical Unit is defined as the *mean* distance between
earth and sun,
...

A bit of rummaging around on the Web shows that the definition is a lot
more complex than that. This seems typical
" the radius of an unperturbed circular orbit a massless body would
revolve about the sun in 2*(pi)/k days (i.e., 365.2568983.... days),
where k is defined as the Gaussian constant exactly equal to
0.01720209895." http://neo.jpl.nasa.gov/glossary/au.html

That's not even grammatical, at least in our language.

Diverted to a group more suited to rational discussion, and accompanied
by a suggestion for ST that FAQ W.18 might possibly be modified to give
or point to the current authoritative international standard definitions
(if there be such).

Does/should the Light Year depend on the Tropical Year or the
SI/Gregorian one?

Is the AU *defined* as 149 597 870 660 000 metres, with "mean
separation" being merely icing on the cake - or /vice versa/? In other
words, can new radar work change that number, or is it now as fixed as
299 792 458 m/s is?

--
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