Re: Shadow of sundial a straight line on equinox day?

oriel36 wrote:

On Apr 2, 2:34 am, starman <star...@xxxxxxxxxxx> wrote:

Let's forget about the global warming issue until you first give a
satisfactory answer to the pending question in this thread. You are
basing your understanding of the relationship between the inclination
(tilt) of the earth's rotational axis in relation to it's orbital plane
(around the sun), on imaging and other observations, which is fine.
However I'm asking you to explain the underlying principle of physics
which causes the observed behavior of the planets such as Uranus, which
you like to use as an example. Specifically, why does the earth's
rotational axis remain fixed to the same point in space, like your
broomstick analogy, while the earth orbits the sun? Or to put the
question in the negative, why *doesn't* the axis of the earth's rotation
always point *towards* the sun during it's annual orbit? If this were
true, it would be like the broomstick always pointing towards the basket
in the center of the room while the student walks around it. I think you
will agree that this is not the case but why? It might be helpful if you
do some research on a child's toy which is often used as an
instructional aid in a high school physics class. Hint: The name begins
with the letter 'G'.


I mistakenly hit the send button and do not feel like removing the
post.

The teacher here can safely teach his students what causes the seasons
without adding complications such as variable orbital speed or how the
natural noon cycles vary due to the specifics of orbital motion allied
with daily rotation.He is under no obligation to explain why the old
explanation based on hemispherical 'tilt' towards and away from the
Sun was an inclusive,limited and ultimately flawed way to explain the
seasons whereas it takes the orbital motion of the Earth and the
specific way its orbits the Sun to account for the entire seasonal
cycle.I often used the analogy of a crank pin as it 'orbits' the
central shaft to carry the point for the orbital behavior of the
planet but this is in lieu of people who will provide exciting
descriptions via graphics or images -

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

If you are absolutely intent on dumping everything into daily rotation
and its orientation/tilt then go right on ahead,I would always appeal
to others to try and provide the new and better description which uses
the orbital specific to do the job.It is indeed very important but not
as a weapon to promote or deny global warming but strictly something
that can be enjoyed with the consequences for climate following from
the modification.

My only intention was to get you to do a little research to discover the name and principles of the device or educational tool starting with the letter 'G' which explains why the rotational axis of the earth remains fixed to the same location in space, like your broomstick does in the room. Haven't you ever wondered why this is so? I guess you made no attempt to do that research. All I'm asking for is the name of that device. If you can not provide it, you do not truly understand the underlying physical principles which govern the behavior of any rotating body, whether it be a planet or just a child's toy top. I imagine there are more than a few readers here who are waiting to see if you can do it. No spoilers please.
Last chance, what's the word?
.

Quantcast