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Two dumb questions



 
 
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  #1  
Old July 10th 05, 06:38 PM
Friar Broccoli
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Default Two dumb questions

Hi;

Dumb question #1:

It is my understanding that about 4 billion years ago the
moon was much closer to the earth than today (correct ?).
and as a result of bumping into dust/asteroids etc. it has
gradually lost energy and therefore moved AWAY from the
earth.

My intuition tells me that as the moon looses
energy/momentum it should be less able to resist earth's
gravity, and therefore move NEARER to the earth. Why is my
intuition wrong?


Dumb question #2:

I live in Quebec City Canada, which is somewhere around the
47th parallel. Since that is far north of the Tropic of
Cancer (the most northerly height of the sun in late June) I
had always just assumed that the sun would ALWAYS be south
of east in the morning, and south of west in the evening.

Recently I noticed that that does not appear to be the case.
In late June, if I draw a line pointing to the sun first
thing in the morning, and another just before the sun goes
down, the interior angle is a lot less than 180 degrees. It
appears that this angle is about 150 degrees on the NORTH
side of my house. This makes no sense to me and is
beginning to drive me insane. I assume I am seeing the sun
north of east/west in the morning/evening, but why?

Cordially;


Friar Broccoli
Robert Keith Elias, Quebec, Canada Email: EliasRK (of) gmail * com
Best programmer's & all purpose text editor: http://www.semware.com

--------- I consider ALL arguments in support of my views ---------

  #2  
Old July 10th 05, 08:04 PM
N:dlzc D:aol T:com \(dlzc\)
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Default

Dear Friar Broccoli:

"Friar Broccoli" wrote in message
ps.com...
Hi;

Dumb question #1:

It is my understanding that about 4 billion years ago the
moon was much closer to the earth than today (correct ?).
and as a result of bumping into dust/asteroids etc. it has
gradually lost energy and therefore moved AWAY from the
earth.


This "moving away" stuff *requires* energy/momentum... not the
loss of it.

My intuition tells me that as the moon looses
energy/momentum it should be less able to resist earth's
gravity, and therefore move NEARER to the earth. Why is my
intuition wrong?


It isn't. The recession of the Moon is largely driven by the
Earth's tides. Angular momentum is transferred from the Earth to
teh Earth-Moon system, in much the same way a miner panning for
gold can radially accelerate water in his pan. By slightly
shifting the center of mass.

Dumb question #2:

I live in Quebec City Canada, which is somewhere around the
47th parallel. Since that is far north of the Tropic of
Cancer (the most northerly height of the sun in late June) I
had always just assumed that the sun would ALWAYS be south
of east in the morning, and south of west in the evening.

Recently I noticed that that does not appear to be the case.
In late June, if I draw a line pointing to the sun first
thing in the morning, and another just before the sun goes
down, the interior angle is a lot less than 180 degrees. It
appears that this angle is about 150 degrees on the NORTH
side of my house. This makes no sense to me and is
beginning to drive me insane. I assume I am seeing the sun
north of east/west in the morning/evening, but why?


Nearer the geographic North pole, the Sun never sets in the
summer. Your assumption of "less than 180 degrees" is incorrect.
Be OK for a flat-earther, though. ;)

David A. Smith


  #3  
Old July 10th 05, 08:20 PM
N:dlzc D:aol T:com \(dlzc\)
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Posts: n/a
Default

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in message news:qjeAe.25726$Qo.4513@fed1read01...
....
It isn't. The recession of the Moon is largely driven by the
Earth's tides. Angular momentum is transferred from the Earth
to teh Earth-Moon system, in much the same way a miner panning
for gold can radially


"tangentially" not radially...

accelerate water in his pan. By slightly shifting the center
of mass.


Sorry about that...

David A. Smith


  #4  
Old July 10th 05, 08:31 PM
external usenet poster
 
Posts: n/a
Default

To Friar

To really appreciate what is happening beyond the illusion of sunset
and sunrise and equatorial orientation to the Sun it is best to order
things according to their correct properties.

First things first - the earth's axial orientation is more or less
constant over the course of a year,you can check this by the North star
Polaris -

http://homepage.mac.com/tarashnat/as.../0001-08a.jpeg

As the Earth's polar axis is fixed to Polaris ,it follows that the
Earth's Equator at 90 degrees to the axis will also remain fixed -

http://www.qrg.northwestern.edu/proj...quator-45s.gif

What causes the seasons is not axial tilt to the Sun or orbital plane
but the change orientation of the Earth in its orbit around the Sun,it
stands to reason as the Earth as a whole does not tilt (see Polaris) so
something else has to cause the illusion.

It was a decision by 17th/18th century cataloguers to furnish the
Earth with an axial tilt property to the Sun for their agenda in trying
to solve the Longitude problem and it will drive you insane if you are
not careful enough to escape the bluffing and blustering.

It may be initially difficult to see things from a changing orbital
orientation passing through a fixed Earth orientation as the main
factor in seasonal differences but it certainly is worth the effort for
the alternative is just slightly better than a flat Earth i.e. a
hemispherical Earth like this description where axial tilt to the Sun
is attributed as a cause -

http://www.schoolsobservatory.org.uk...easonsanim.htm

There is an enormous difference between recognising Keplerian orbital
changes passing through fixed axial orientation and the inferior view
of axial tilt to the Sun.

  #5  
Old July 11th 05, 12:14 AM
Llanzlan Klazmon
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Posts: n/a
Default

"Friar Broccoli" wrote in
ps.com:

Hi;

Dumb question #1:

It is my understanding that about 4 billion years ago the
moon was much closer to the earth than today (correct ?).
and as a result of bumping into dust/asteroids etc. it has
gradually lost energy and therefore moved AWAY from the
earth.


The movement of the Moon away from the Earth is caused by transfer of
angular momentum from the Earth's rotation to the Moon's orbit. This
comes about through tidal interaction and has nothing to do with
dust/asteroids etc. BTW the Moon's orbit has greater energy than when
the semi-major axis was less than it is now. Note that this also means
the period of the Earth's rotation is slowing lengthening. i.e the day
is slowly getting longer.


My intuition tells me that as the moon looses
energy/momentum it should be less able to resist earth's
gravity, and therefore move NEARER to the earth. Why is my
intuition wrong?


See above.




Dumb question #2:

I live in Quebec City Canada, which is somewhere around the
47th parallel. Since that is far north of the Tropic of
Cancer (the most northerly height of the sun in late June) I
had always just assumed that the sun would ALWAYS be south
of east in the morning, and south of west in the evening.


No. The extreme case is at the poles where the Sun doesn't set at all at
the height of summer.


Recently I noticed that that does not appear to be the case.
In late June, if I draw a line pointing to the sun first
thing in the morning, and another just before the sun goes
down, the interior angle is a lot less than 180 degrees. It
appears that this angle is about 150 degrees on the NORTH
side of my house. This makes no sense to me and is
beginning to drive me insane. I assume I am seeing the sun
north of east/west in the morning/evening, but why?


The Earth's axis is tilted a little over 23 degrees to the 'normal' of
the ecliptic. The ecliptic is the plane of the Earth's orbit about the
Sun, which is thereby tilted at a little over 23 degrees to the plane of
the Earth's equator. On the day of the northern Summer soltice, the
Sun's declination is a bit over 23 degrees North of the equator. It's
just a bit of projective geometry. Download a skycharting program and
explore.

Klazmon.



Cordially;


Friar Broccoli
Robert Keith Elias, Quebec, Canada Email: EliasRK (of) gmail * com
Best programmer's & all purpose text editor: http://www.semware.com

--------- I consider ALL arguments in support of my views ---------


  #6  
Old July 11th 05, 01:05 AM
Friar Broccoli
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Posts: n/a
Default

Thanks to Llanzlan Klazmon and "N:dlzc D:aol T:com (dlzc)"
(how do you get David Smith from that?) for your useful
responses.

N:dlzc D:aol T:com (dlzc) wrote:

This "moving away" stuff *requires* energy/momentum... not the
loss of it.


Glad to hear it.

The recession of the Moon is largely driven by the Earth's
tides. Angular momentum is transferred from the Earth to
teh Earth-Moon system, in much the same way a miner
panning for gold can radially accelerate water in his pan.
By slightly shifting the center of mass.


I didn't understand this till I read "Llanzlan Klazmon" comment:

The movement of the Moon away from the Earth is caused
by transfer of angular momentum from the Earth's rotation
to the Moon's orbit.


Right now I still don't REALLY understand, but I'm pretty
sure that I will get it after reflecting on the earth's
rotation and tides for a few days/weeks.

Nearer the geographic North pole, the Sun never sets in the
summer. Your assumption of "less than 180 degrees" is
incorrect. Be OK for a flat-earther, though. ;)


This definitely has not sunk in yet, but this gives me a new
way of trying to visualise the situation. Again I should
get it after more reflection.

If I fail, I will add acceptance of a flat earth to the
fundamental tenants of the Broccolist faith.

Thanks again;

Cordially;

Friar Broccoli
Robert Keith Elias, Quebec, Canada Email: EliasRK (of) gmail * com
Best programmer's & all purpose text editor: http://www.semware.com

--------- I consider ALL arguments in support of my views ---------

  #7  
Old July 11th 05, 01:22 AM
Odysseus
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Posts: n/a
Default

Friar Broccoli wrote:

It is my understanding that about 4 billion years ago the
moon was much closer to the earth than today (correct ?).
and as a result of bumping into dust/asteroids etc. it has
gradually lost energy and therefore moved AWAY from the
earth.


No, it has gained energy from the Earth by means of tidal forces,
vaguely like 'pumping' a playground swing higher and higher by
shifting your centre of gravity in synch with its period. In return
the rotation of the Earth has been slowed, so that our day is longer
than it used to be.

My intuition tells me that as the moon looses
energy/momentum it should be less able to resist earth's
gravity, and therefore move NEARER to the earth. Why is my
intuition wrong?


If the Moon did experience a net loss of energy its orbit would
indeed tend to contract, but see above.


I live in Quebec City Canada, which is somewhere around the
47th parallel. Since that is far north of the Tropic of
Cancer (the most northerly height of the sun in late June) I
had always just assumed that the sun would ALWAYS be south
of east in the morning, and south of west in the evening.


You seem to be mixing up two different phenomena: the height of the
Sun at noon, and the displacement of sunrise and sunset from due east
& west (and from their 'nominal' solar times of 6h00 and 18h00) respectively.

Recently I noticed that that does not appear to be the case.
In late June, if I draw a line pointing to the sun first
thing in the morning, and another just before the sun goes
down, the interior angle is a lot less than 180 degrees. It
appears that this angle is about 150 degrees on the NORTH
side of my house. This makes no sense to me and is
beginning to drive me insane. I assume I am seeing the sun
north of east/west in the morning/evening, but why?


Well, it's a little hard to explain without diagrams (you could
probably find some by Googling), but let's start by picturing an
observer on the geographic equator. The great circle running from
east to west via the zenith, perpendicular to the horizon, is called
the "prime vertical", and from 0° latitude this coincides with the
celestial equator. So when the Sun is at 0° declination, on the
vernal equinox for example, it rises due east, passes straight
overhead at noon, and sets due west. As the Sun's declination
increases over the next three months, its path remains parallel to
the prime vertical but creeps northwards, so that its rising,
culminating, and setting points are all in the northern half of the sky.

Now imagine that the observer is a little north of the geographic
equator. Although the celestial equator and his prime vertical still
meet on the eastern and western horizons, the former now appears to
be tilted slightly southward (by an angle equal to his latitude), so
that on the vernal equinox the Sun, although rising and setting due
east and west, at noon culminates south of the PV. As the spring
progresses and the Sun moves northward, its culmination point
approaches the zenith at the same pace as was observed from the GE;
meanwhile the sunrise and sunset points are also shifting, but here
the tilt of the CE makes them move north faster than they did there.
To understand why, imagine looking eastward at 0600 solar time. The
Sun's north declination places it not only north of due geographic
east, but above the horizon as well, because celestial north no
longer coincides with geographical north, being elevated by an angle
equal to the latitude (the north celestial pole has the same altitude
above the north horizon). So the Sun has already risen and its path,
still parallel to the CE, is tilted; likewise at solar 18h00 it
hasn't set yet, and the day has become longer than 12 hours.

On a certain date the noon Sun will reach the zenith; from then
through the summer solstice it will spend the entire daytime in the
northern half of the sky. The further north the observer goes, the
later this date of zenith culmination, and the Tropic of Cancer is
the latitude where it falls on the summer solstice. From anywhere
north of this point the noon Sun is always in the southern half of
the sky -- but note that during the summmer it still crosses the PV
twice a day, rising and setting on the north side. Moreover the
increased latitude exaggerates the displacement, making the
inequality of day and night more pronounced. As we get into the
higher temperate latitudes the CE has become closer to the horizon
than to the PV; the summer sun rises and sets at a shallow angle, a
long way north of east and west, making for long twilights and short nights.

At the Arctic Circle an extreme situation is reached; the CE is
'depressed' so far that on the summer solstice the Sun's diurnal
circle only touches the north horizon instead of dipping below it.
From the North Pole the CE coincides with the horizon; since the
Sun's path is (as always) parallel to the CE, its altitude doesn't
change appreciably all day.

I've gone on longer than I intended, but to sum up the northward
displacement of sunrise and sunset in summer *increases* with
latitude; while in the tropics the relative length of day and night
doesn't change very much, and the path of the Sun never strays very
far from the PV, in temperate latitudes the difference between day &
night, and accordingly the difference between the lengths of the
portions of the Sun's diurnal arc lying above & below the horizon,
become quite large.

Everything I've said can be applied to the situation in winter,
_mutus mutandis_.

--
Odysseus
  #8  
Old July 11th 05, 01:52 AM
N:dlzc D:aol T:com \(dlzc\)
external usenet poster
 
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Default

Ddear Friar Broccoli:

"Friar Broccoli" wrote in message
oups.com...
Thanks to Llanzlan Klazmon and "N:dlzc D:aol T:com (dlzc)"
(how do you get David Smith from that?) for your useful
responses.


The "d" is for David. The other three letters are for my wife
and kids.

N:dlzc D:aol T:com (dlzc) wrote:

This "moving away" stuff *requires* energy/momentum...
not the loss of it.


Glad to hear it.

The recession of the Moon is largely driven by the Earth's
tides. Angular momentum is transferred from the Earth to
teh Earth-Moon system, in much the same way a miner
panning for gold can radially accelerate water in his pan.
By slightly shifting the center of mass.


I didn't understand this till I read "Llanzlan Klazmon"
comment:

The movement of the Moon away from the Earth
is caused by transfer of angular momentum from
the Earth's rotation to the Moon's orbit.


Right now I still don't REALLY understand,
but I'm pretty sure that I will get it after
reflecting on the earth's rotation and tides
for a few days/weeks.


Sounds like an excellent plan! If you drink coffee, and you
think about it, get down to the last ounce in the cup. See if
you can get the coffee to "whirl around" in the cup without using
a spoon.

Earth's tides have a center of mass that very slightly leads the
Moon in its orbit (the "leading" is caused by the ocean's
momentum, which tends to pretty much follow the Earth around).
When the tides move around like this (very slightly counter to
the Earth's rotation), it tends to apply a braking torque to the
Earth. The tides boost the Moon's orbit, while slowing the
Earth's rotation.

Nearer the geographic North pole, the Sun never sets in the
summer. Your assumption of "less than 180 degrees" is
incorrect. Be OK for a flat-earther, though. ;)


This definitely has not sunk in yet, but this gives me a new
way of trying to visualise the situation. Again I should
get it after more reflection.

If I fail, I will add acceptance of a flat earth to the
fundamental tenants of the Broccolist faith.

Thanks again;


Good luck. Llanzlan Klazmon's response should lead you in the
right direction.

David A. Smith


  #9  
Old July 11th 05, 02:32 PM
external usenet poster
 
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Default



OG wrote:
wrote in message
ups.com...
To Friar

To really appreciate what is happening beyond the illusion of sunset
and sunrise and equatorial orientation to the Sun it is best to order
things according to their correct properties.

First things first - the earth's axial orientation is more or less
constant over the course of a year,you can check this by the North star
Polaris -

http://homepage.mac.com/tarashnat/as.../0001-08a.jpeg

As the Earth's polar axis is fixed to Polaris ,it follows that the
Earth's Equator at 90 degrees to the axis will also remain fixed -

http://www.qrg.northwestern.edu/proj...quator-45s.gif

What causes the seasons is not axial tilt to the Sun or orbital plane
but the change orientation of the Earth in its orbit around the Sun,it
stands to reason as the Earth as a whole does not tilt (see Polaris) so
something else has to cause the illusion.

It was a decision by 17th/18th century cataloguers to furnish the
Earth with an axial tilt property to the Sun for their agenda in trying
to solve the Longitude problem and it will drive you insane if you are
not careful enough to escape the bluffing and blustering.


Gerald has not been driven insane, but he has lost the plot on this matter.
It is reasonable to ask what he means by this, but since he doesn't really
understand that the 'change orientation of the Earth' is caused by 'axial
tilt to the orbital plane', he has real problems in explaining himself.

If contradicted he tends to end up with abuse.


Not at all,the change in orbital orientation of the Earth can be
graphically represented against a fixed axial orientation.

http://www.mhhe.com/physsci/astronom...ages/04f15.jpg

Unfortunately cataloguers are inclined NOT to see tha change in orbital
orientation because Flamsteed combined axial and orbital motion working
off the Earth's axis is order to justify axial rotation at 23 hours 56
min 04 sec.See -

http://astrosun2.astro.cornell.edu/a...dereal_day.gif

It is initially tricky but because polar axial orientation is more or
less constant and there is no much more you can say about it -

http://homepage.mac.com/tarashnat/as.../0001-08a.jpeg

In falls to the change in orbital orientation at roughly 90 degrees to
where hemispherical cataloguers have it (Equatorial axial tilt) that
causes seasonal changes.I have said many times that 17th century
cataloguers were only interested in solving the Longitude problem
through tying the celestial sphere to terrestial longitudes but to do
that they have to perform some awful surgery on some exquisite
astronomical principles.

More importantly,at dawn and dusk on the Equinox the terrestial
longitudes representing the Earth's axial rotation and axis run
parallel with orbital orientation and for a few moments we escape the
illusion generated by axial rotation and see the orbital motion of the
Earth on its own.

  #10  
Old July 11th 05, 04:06 PM
external usenet poster
 
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Default

To Klazmon

Your explanation is basically derived from the cataloguers of the 18 th
century who found it necessary to explain away the Equation of Time by
bringing in an inapprorpriate analemmatic feature based on Equatorial
orientation to the Sun.The EoT has nothing whatsoever to do with
daylight/darkness asymmetry or the solstice which denotes the
hemispherical extremes of that feature but most continue to bluff and
bluster,up to and including Nasa.

http://imagine.gsfc.nasa.gov/docs/as...s/980116c.html

In will not make sense to have the Earth's axis tilt to the orbital
plane to generate that illusion of the Sun passing at higher elevations
during the summer (hemispherical term) so the other option is to ignore
axial orientation and Equatorial orientation altogether and concentrate
on the Earth's orbital motion and orientation.

Here is what the Earth's faster motion taking an inner heliocentric
orbital circuit looks like against the motion of Jupiter and the slower
and outer moving Saturn

http://www.opencourse.info/astronomy...turn_retro.gif

This takes care of the great Copernican insight and how the early
heliocentrists understood the heliocentric system and it is as exciting
today as it was back then.

Now as for orbital orientation as changing over an annual orbit -

This graphic gives a rough idea of the planet's orientation to the Sun
generating a division between planetary sunlight and planetary shadow
(which we call 'night'),for convenience any old analogy will do -

http://www.phschool.com/science/scie...strange_01.jpg

The great error in explaining seasonal changes for the entire planet
and at once ! is that the real cause is not to be tempted into
explaining axial tilt variations against the orbital plane but by the
altering of orbital orientation in a longitudinal way for only two
times during an annual orbit at the Equinoxes will the orbital
orientation align with the polar terrestial axial longitudes with a
maximum variation at noon.

Go ahead and try it,it works far better than axial tilt to the
Sun/orbital plane for it removes the need for spliting the Earth into
seperate hemispheres and will get rid of that nasty 17th century
analemmatic maneuver which causes the problem.















*http://www.bodley.ox.ac.uk/cgi-bin/i...x.x.54 .x.336

 




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