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The theory of gravity



 
 
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  #101  
Old July 28th 17, 05:01 AM posted to sci.astro.amateur
Quadibloc
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Default The theory of gravity

On Wednesday, July 5, 2017 at 1:22:48 AM UTC-6, Gerald Kelleher wrote:

Equating planetary motion with the fall of an apple may have appeared
fashionable in the late 17th century but unsuitable for 21st century
observational data which requires astronomers to interpret and not mathematical
theorists or experimentalists.


And the world is like an apple
Whirling silently in space

https://www.youtube.com/watch?v=qKV9bK-CBXo

John Savard
  #102  
Old July 28th 17, 05:28 AM posted to sci.astro.amateur
Quadibloc
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Default The theory of gravity

On Thursday, July 27, 2017 at 10:01:27 PM UTC-6, Quadibloc wrote:
On Wednesday, July 5, 2017 at 1:22:48 AM UTC-6, Gerald Kelleher wrote:


Equating planetary motion with the fall of an apple may have appeared
fashionable in the late 17th century but unsuitable for 21st century
observational data which requires astronomers to interpret and not mathematical
theorists or experimentalists.


And the world is like an apple
Whirling silently in space


https://www.youtube.com/watch?v=qKV9bK-CBXo


....but seriously, dismissing Oriel36 as "crazy" is missing the point.

In ancient times, people thought of the heavens as fundamentally different from
things on the Earth, working by a different set of rules. After all, the Moon
moves in the sky as it has for as long as anyone can remember. On Earth, things
that move slow down and stop without a constant input of energy. And anything
that's not sitting solidly on the ground will quickly fall down.

This is a way of thinking that was overthrown by Newton - he showed how a body
in orbit, even though it didn't proceed to the ground, was still "falling",
because its path was a curved path around its primary instead of a straight
line.

To people of the modern day, it is as natural as breathing that science seeks to
understand and explain things as thoroughly as it can manage - and one of the
first steps is to see if the principles that work with the things we know can
also be applied to what is unknown. There isn't some kind of rule that says
"this is different, you can't use those principles here" - but if you go ahead
and try and fail, then you haven't applied them correctly, and you can still try
again.

Also, it's clear enough that we are right and the ancients were wrong - or at
least we're closer to the truth. We make shinier machines - and Newton's use of
gravity, angular momentum, and all these other physical things for planetary
motion was vindicated when perturbations allowed the position of Neptune to be
predicted before anyone saw it.

Oriel36 seems to be someone who has read the writings of the ancients and
admired their thinking, and he has internalized their world view. He can accept
Copernicus and Galileo and Kepler... but not Newton...

because he is the last Aristotelian left standing!

John Savard
  #103  
Old July 31st 17, 10:29 AM posted to sci.astro.amateur
[email protected]
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Default The theory of gravity

On Friday, July 28, 2017 at 3:11:08 AM UTC+1, Gerald Kelleher wrote:
I do not have the time to waste


This is perhaps the wrongiest statement you have ever made in a long history of wrongness.
  #104  
Old July 31st 17, 07:23 PM posted to sci.astro.amateur
Gerald Kelleher
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Default The theory of gravity

In summary, Newton didn't have a theory of gravity but rather tried to reduce astronomical,its observations and insights into experimental sciences. A theory of gravity would be like Kepler's guess that implied electromagnetic forces generated by rotation of larger objects imparts orbital motion on smaller objects -

"The Sun and the Earth rotate on their own axes...The purpose of this
motion is to confer motion on the planets located around them;on the
six primary planets in the case of the Sun,and on the moon in the case
of the Earth.On the other hand the moon does not rotate on the axis of
its own body,as its spots prove " Kepler

This notion survived in Royal Society circles until Newton's notion suffocated the approach although I believe Nicolas Tesla went back to considering electromagnetic influences on orbital motion.

For my part I too am free to speculate as normally it is no harm and separate to my inputs into astronomy and besides, I mentioned it more than a few times throughout the few decades. The Sun has a forward motion through space as the solar system and the other stars move in a Galactic orbital circle.. It means the planets spend half their time travelling with the central Sun in that Galactic orbital motion and half their orbit travelling in the opposite direction. As orbital speeds increase closer to the Sun, the planets speed up as they are constantly deflected due to the forward orbital motion of the Sun . In other words the variable orbital speed of the Earth and other planets is a combination of heliocentric orbital motion and galactic orbital motion. It doesn't matter if it is correct or not however it does take in a wider view .

The sheer volume of data over the last 50 years should have inspired individuals to actually consider the variable speeds of the planets in terms of magnetism rather than the abysmal idea that planet motions equates directly to a falling apple and the awful attempt to make predictive astronomy mesh with predictive experimentation.


  #105  
Old July 31st 17, 08:03 PM posted to sci.astro.amateur
palsing[_2_]
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Default The theory of gravity

On Monday, July 31, 2017 at 11:24:00 AM UTC-7, Gerald Kelleher wrote:

"The Sun and the Earth rotate on their own axes...The purpose of this
motion is to confer motion on the planets located around them;on the
six primary planets in the case of the Sun,and on the moon in the case
of the Earth.On the other hand the moon does not rotate on the axis of
its own body,as its spots prove " Kepler


Kepler, of course, was later proven wrong about his assessment of the moon's lack of apparent rotation. The moon is tidally coupled to the Earth's own rotation, which means that its orbital and rotational motions are essentially equal.

Of course, you will become enraged by such heresy, but nevertheless it is the case.

“The good thing about science is that it's true whether or not you believe in it.”
― Neil deGrasse Tyson
  #106  
Old July 31st 17, 11:00 PM posted to sci.astro.amateur
Gerald Kelleher
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Default The theory of gravity

On Monday, July 31, 2017 at 8:03:05 PM UTC+1, palsing

There is no right or wrong, there is just the spirit to enjoy the spectacle and all that is gained for people who love astronomy and not merely their own pictures.

https://stereo.gsfc.nasa.gov/img/total_lg.gif

For once the Earth returns the favor of illuminating the side of the moon that offers the romantic spectacle on the full moon where the same craters that are lit up by the Sun become visible by the reflected light of our own planet.

https://www.mythicalireland.com/anci...toneillust.gif

Over 5200 years ago they understood the principle of the moon lost in the glare of the Sun for a few days and no doubt it had the created the same awe that the upcoming eclipse will on today's viewers.

The solar eclipse is a miracle as it breaks the normal hard shell of familiarity where you have lost the sense of wonder of creation. I find it every day in what I do and see in walks or in the imaging provided by the big telescopes or efforts of astrophotographers.

  #107  
Old August 1st 17, 02:09 AM posted to sci.astro.amateur
Quadibloc
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Default The theory of gravity

On Monday, July 31, 2017 at 12:24:00 PM UTC-6, Gerald Kelleher wrote:
In summary, Newton didn't have a theory of gravity but rather tried to reduce
astronomical,its observations and insights into experimental sciences.


He didn't just try. He succeeded.

John Savard
  #108  
Old August 1st 17, 08:33 AM posted to sci.astro.amateur
Gerald Kelleher
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Default The theory of gravity

I am looking at the other thread of the astrophotographer and there isn't the slightest hint of describing the moon's orbital motion in terms of a Sun centered structure nor the positions of the three celestial bodies in relation to each other. In this case I marvel at the reflected light of the Earth on the moon's surface as the fully illuminated face of the Earth stands directly against the fully dark face of the moon at the moment of the eclipse -

https://stereo.gsfc.nasa.gov/img/total_lg.gif

There is some joy in being able to reason why the same face of the moon can be seen on the eclipse much like it is seen each full moon with the difference between reflected light of the Earth for the former and direct radiation from the Sun for the latter.



  #109  
Old August 1st 17, 08:54 PM posted to sci.astro.amateur
Gerald Kelleher
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Default The theory of gravity

On Monday, July 31, 2017 at 8:03:05 PM UTC+1, palsing wrote:
On Monday, July 31, 2017 at 11:24:00 AM UTC-7, Gerald Kelleher wrote:

"The Sun and the Earth rotate on their own axes...The purpose of this
motion is to confer motion on the planets located around them;on the
six primary planets in the case of the Sun,and on the moon in the case
of the Earth.On the other hand the moon does not rotate on the axis of
its own body,as its spots prove " Kepler


Kepler, of course, was later proven wrong about his assessment of the moon's lack of apparent rotation. The moon is tidally coupled to the Earth's own rotation, which means that its orbital and rotational motions are essentially equal.

Of course, you will become enraged by such heresy, but nevertheless it is the case.


The moon orbiting the Earth is no different than a car circling a traffic roundabout where one side of the car always faces the roundabout while the other side faces away .This scales up to the moon orbiting the Earth and spectacular on the solar eclipse -

https://apod.nasa.gov/apod/image/000...endler_big.jpg

https://www.nasa.gov/sites/default/f...ght_corona.jpg

Anyone can declare -beautiful,fantastic,amazing at the image of the moon in the other thread but these are empty words among people who never followed the understanding of the original Sun centered astronomers or indeed the ancient astronomers who were aware the moon orbiting the Earth.

I don't mind what you inflict upon yourselves but it is criminally unjust to prevent the wider population from appreciating these facets of the eclipse event.



  #110  
Old August 1st 17, 09:21 PM posted to sci.astro.amateur
Quadibloc
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Default The theory of gravity

On Tuesday, August 1, 2017 at 1:54:41 PM UTC-6, Gerald Kelleher wrote:

The moon orbiting the Earth is no different than a car circling a traffic
roundabout where one side of the car always faces the roundabout while the other
side faces away.


In one way that's true, that is a good general analogy to its motion.

And it's true we don't say that a car on such a roundabout is spinning; it is
merely being driven in a circular path - just as the Moon goes along its orbit,
which is a (nearly) circular path.

So why do we perversely say that the Moon rotates on its axis?

When we don't say a car on a roundabout is doing any such thing?

Well, for one thing, the Moon doesn't have *tires*.

To move in its orbit around the Earth, it isn't... touching anything. It isn't
held or grasped by anything. Not in a way that rigidly constrains which way it
faces - it is free to rotate, just as the Earth, orbiting the Sun, is able to
have a 24 hour day.

And because the Moon's orbit is elliptical, we sometimes see a little extra of
the Moon on the right or left side - libration - because the Moon doesn't always
face in exactly the same way towards Earth all the time.

Instead, its relationship to the stars proceeds *uniformly* by mechanical clock
time, with the same *average period* as its orbit around the Earth. So it faces
to the Earth, but it wiggles because its orbit isn't a perfect circle but an
ellipse instead.

This is why we judge the Moon's rotation (or lack thereof) in relation to the
stars and not in relation to the Earth. In relation to the stars, it rotates
once in about 27 1/3 days. Giving phases in 29 1/2 days, and giving a situation
where one side always faces the Earth.

What takes place at a constant rate by mechanical time is possibly a simple
motion; that which slows down and speeds up is a compound motion. The Moon's
libration and the Equation of Time for the solar day show that rotation with
respect to a primary is compound, not fundamental - just as retrogrades showed
Copernicus that the fundamental motions of the planets are around the Sun, not
the Earth.

John Savard
 




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