simple Parallax equation

On Apr 21, 9:46*pm, "Robert" wrote:
"oriel36" *wrote in message

...

The whole precept of orbital motion referenced to the celestial sphere
has to be jettisoned and especially Bradley's invalid view.,the
replacement is based on referencing orbital motion to the central Sun.

Umm... we are talking about an introductory astronomy class.

So am I.

A planet has a rotational orientation meaning that its rotation
produces this effect -

http://www.robertreeves.com/star_tra...06_9pm-6am.jpg

These guys call it 'tilt' and then turn it into a dynamic where the
Northern hemisphere 'tilts' towards the Sun in summer and 'tilts' away
in winter.This is incorrect.What occurs is a motion that goes through
a full 360 degrees but to enjoy that motion you have to let go of the
idea parallax ,the pseudo-dynamic of axial tilt and take your
lessons from what the Uranus tells you.

The axial orientation,again,due to axial rotation keeps Uranus
pointing in one direction in space just like the Earth-

http://physics.uoregon.edu/~jimbrau/...13/FG13_06.jpg

Uranus has something special in that it has Equatorial rings which
allow a person to see the direction of axial rotation -

http://space.newscientist.com/data/i...2529-1_800.jpg

An observer on the dark side of Uranus see the same Polaris 'effect'
as we do on Earth but that effect is solely due to axial rotation.The
change in seasons has to come from somewhere else so then you look at
the orbital motion of the planet along with a basic analogy -

http://physics.uoregon.edu/~jimbrau/...13/FG13_06.jpg

http://www.youtube.com/watch?v=YV9WkQkUHZ4

As long as you remeber to keep axial and orbital motions apart,focus
on one or the other but not as a combined motion then you will be
fine.


The apparent progression of stars over the course of an annual orbit
is due to the fact that a location ,apart from axial rotation,will be
orbitally facing the Sun,a half year later will be pointing in the
opposite direction just link the crank pin on an engine points towards
the central shaft,sometimes perpendicular and sometimes away,apply the
graphic of Uranus and then apply the same for the Earth.

It alows you to see why the natural noon cycles are unequal and the
combined effect of two seperate motions axial rotation and the change
which occurs orbitally with respect to the Sun.Take your time and if
you do not get it then wait a few years and try again.









http://www.youtube.com/watch?v=YV9WkQkUHZ4