Arthur Carlson wrote:
> On the other hand, since we are talking about a correction
> to a correction to solar time, we could probably live with the error
> on a 10,000 year time scale.
Arthur,
You still appear to be asserting that in calculating the Longitude of
Perihelion (over a 10,000 year period), only Precession need be considered and
the
shifting of Perihelion due to perturbation and other smaller combined effects
can
be ignored. I'm sorry to appear picky, but this assertion is most definitely
incorrect. I can only recommend that you do the calculations for yourself and
post
your findings. Below I have calculated the pertinent factors for evaluating the
EoT where theta is ecliptic longitude and EoT is TA-TM in mins of time. I have
as
well have attached a graph that clearly shows how the EoT will vary over the
given
period.
Year = 2000
Eccentricity = 0.0167086
Obliquity = 23.437687
Perihelion = 282.937350
EoT = 9.861*sin(2*theta) - 7.658*sin(theta-282.94)
Year = 12000
Eccentricity = 0.0112689
Obliquity = 22.613159
Perihelion = 99.490350
EoT = 9.162*sin(2*theta) - 5.165*sin(theta-99.49)
Note that the difference in the Longitude of Perihelion is 183.447 degs
and given the Equinoxes are precessing at 50 arc-secs per year (and is fairly
linear) then after 10,000 years precession will have contributed approx. 138.9
degs. I think this should clarify the relative weights of the various effects.
FINIS
Attachment converted: MAC Hard Disk:EOTS.GIF (GIFf/JVWR) (00006DE5)
