Re: Fair orbital question

"Spaceman" <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in news:Eb-
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"bz" <bz+sp@xxxxxxxxxxxxxxxxxxxx> wrote in message
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"Spaceman" <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
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No,
next important is to find the cause for the changes
in solar view time.
That is from the eliptical orbit. (it occurs without any tilt)

NO! The solar view time is caused by the tilt.
We see the sun for the longest time when our hemisphere is the one tilted
toward the sun.
We see the sun for the shortest time when our hemisphere is the one tilted
away from the sun.

If we are at the north pole, we see the sun for 24 hours at mid summer.
If we are at the north pole, we do NOT see the sun at all at mid winter.

If you look down on the orbit
fall /


---> summer sun ---> winter


spring /


I couldn't draw the ellipse but imagine it is there.
in the fall and spring views, you see the '/' representing the axis of the
earth, as seen from the side. The north pole is on the top, right end of
the line.
in the summer and winter, you see the ---> representing the axis of the
earth, as seen from above.
the '>' is the north pole.

If there were no tilt in the axis, you would have
fall |


. summer sun . winter


spring |

The north pole is on the top of the '|' and on the top end of the line
that
we are looking down in summer and winter and seeing as '.'.

bz,
you really need to think about this without the tilt.

I did. Second case above. No tilt.

You will see the tilt is not needed for the seasonal change to occur.

No [significant] change in day length. Remember, that the max and min
distance from the sun are only different by ~2 percent. If ALL of that showed
up as a difference in day length (it wouldn't[why wouldn't it? because the
only difference in length of day will be due to the difference in apparent
SIZE of the sun as seen from earth, think about it!]), then out of a day that
is 86400 seconds long, that is 1728 seconds or 28.8 minutes.

Do you think that a difference in length of day of less than half an hour is
going to make seasons?

Currently, the difference is 100% at the poles. At My latitude the difference
amounts to several hours. At the equator the difference is essentially zero.




There would be no changes in the length of days at any particular latitude
if the axis were vertical.

Yes there would unless the orbit is perfect (non eliptical)
An eliptical orbit is the main cause, the tilt simply increases the
differences.

No. The tilt MAKES the difference significant. Without the tilt, there is no
significant difference. Do the trig. Put yourself on the equator of a
perfectly vertical axis earth. Calculate the sunrise and sunset times at
point of closest approach to the sun ["mid summers day"] and then calculate
the sunrise and sunset times when the earth is at max distance from the sun.

You will find that your "mid summer nights dreams" are almost as long as your
"mid winter nights dreams".




Every day and night at the equator would be equal. Sunrise and sunset
would
be quick.

No, they won't with an eliptical orbit.
They only would be the same with a perfect circular orbit.

We are so close to a perfect circle as to make the difference insignificant.
Do the calculations yourself. You won't believe if someone else does them.

and even if you add the tilt to a perfect orbit, no seasons occur.
Wrong. Look at my first diagram. Even with a perfect circular orbit, the
north pole gets sun for 24 hours a day in mid summer and for zero hours a day
in mid winter.

Again, you need to drop "the textbook answer" and think on your
own.

I do think on my own. Get a globe and a flashlight. Do the experiments
yourself.
Put the globe 11563 diameters away from the flashlight.
Then, move the globe so it is 11963 diameters away from the flashlight.
Don't change the tilt at all.
Measure the difference in angle of the center of the flashlight as seen from
the north pole.

You will find that the difference is insignificant.

If our orbit were perfectly circular then the globe would sit at 11763 earth
diameters away from the 'sun' all the time.

Oh, remember that you are also moving from 105 solar diameters to 109 solar
diameters away from that flashlight.

If you understand trig, you should see very clearly that the small
eccentricity of our orbit has very little effect. Not enough to give any
'seasons' on a planet in the same orbit but without our tilt.

Stop and think and reexamine your assumptions. Do the calculations yourself.
You will see that I am right.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+sp@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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