Southern cross

  • 19 Replies
  • 4997 Views
?

Lykus

  • 4
  • +0/-0
Southern cross
« on: February 12, 2017, 10:22:53 AM »
So first post here. Sry for all mistakes English is not my first language.

I just read through the FAQ and encountered one question. What about different constellations of stars which are only visible in certain areas? eg. g. the southern cross?

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #1 on: February 12, 2017, 06:06:47 PM »
There are different stars in different places?
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

?

Canadabear

  • 2525
  • +0/-0
Re: Southern cross
« Reply #2 on: February 13, 2017, 07:11:51 AM »
There are different stars in different places?

what he is questioning is that you can not see the constellation southern cross from the northern part of the world like Canada.
Like also you can not see the Polaris form the southern part like Australia.

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #3 on: February 13, 2017, 02:47:26 PM »
Maybe different stars are in different places?

E.g southern cross in the south?
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

?

Canadabear

  • 2525
  • +0/-0
Re: Southern cross
« Reply #4 on: February 13, 2017, 03:32:23 PM »
Maybe different stars are in different places?

E.g southern cross in the south?

But should they not all visible in the flat earth idea.

*

rabinoz

  • 26528
  • +0/-0
  • Real Earth Believer
Re: Southern cross
« Reply #5 on: February 13, 2017, 07:28:03 PM »
Maybe different stars are in different places?
E.g southern cross in the south?
Just maybe that's why I can usually, though not always, see the Southern Cross out my back door.

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #6 on: February 13, 2017, 10:32:34 PM »
Maybe different stars are in different places?
E.g southern cross in the south?
Just maybe that's why I can usually, though not always, see the Southern Cross out my back door.

I can also see the southern cross.

Canadabear please explain how you think every star should be visable from a flat earth.

Then I will show you that isn't necessarily the case.
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

?

Canadabear

  • 2525
  • +0/-0
Re: Southern cross
« Reply #7 on: February 14, 2017, 02:27:04 AM »
Maybe different stars are in different places?
E.g southern cross in the south?
Just maybe that's why I can usually, though not always, see the Southern Cross out my back door.

I can also see the southern cross.

Canadabear please explain how you think every star should be visable from a flat earth.

Then I will show you that isn't necessarily the case.
Because according to the Flat Earth Idea all stars are lights on a dome.

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #8 on: February 14, 2017, 03:26:01 PM »
A submission for aisantaros's challenge.

Download the code from GitHub.

* Please feel free to ask for clarification if something isn't clear *

Overview

This model demonstrates the possibility of accurately predicting the location of any star from any location on a flat earth, specifically, the Octans Constellation.

The earth is surrounded by a large "celestial shell", which is normally opaque to visible light. There are numerous holes in the celestial shell, which allows directional light to penetrate the shell and reach the earth. Each hole corresponds to a specific star seen at a specific spot on earth. For each star, there is exactly one hole in the celestial shell that allows a ray of light to hit a specific spot on earth. Given a high enough resolution of the shell (which can be arbitrarily increased by increasing its radius and thickness), the non-continuous nature of the stars would go unnoticed. While this specific arrangement of directional holes seems improbable in the extreme, there is a plausible natural explanation for it, which will be explained in the next section. This plausible natural explanation can be demonstrated to result in the exact same arrangement of stars as what we would expect to see on a globe shaped earth.


Origin of Directional Holes in Celestial Sphere

Imagine a small sphere sitting at the North Pole of the earth. The sphere explodes. Particles are shot outwards in all directions. Once these "guide particles" hit the celestial shell, they drill holes in the shell. These holes allow light from outside the shell to shine back on the earth. Due to the thickness of the celestial shell, the light that penetrates the holes will be highly directional. In fact, the light will only hit the exact spot where the original small sphere exploded. If a person stands in the exact spot where the sphere exploded, he will be able to see light leaking through the numerous holes in the celestial shell. However, if he moves slightly to the side, those holes will disappear, and the sky will again be black.

Now imagine billions (or more) identical small spheres covering the surface of the earth in a single layer. Each sphere is completely identical in every way. When each sphere explodes, it will emit the exact same arrangement of guide particles as every other sphere.

However, each sphere is facing a slightly different direction. Each sphere is rotated towards the North Pole by an amount corresponding to its latitude. Whereas when a sphere at the North Pole explodes, it will shoot a "Polaris particle" straight up, a sphere at 45° north latitude will shoot its "Polaris particle" at an angle of 45°, resulting in a hole that can be seen at an altitude of 45°. The exact same altitude that Polaris would be expected to be seen at from a globe earth.

Likewise, each exploding sphere has its own "Sirius particle", "Betelgeuse particle", "Rigel particle", etc, which allows those stars to be seen from anywhere on earth.

This is roughly illustrated in figure A. This is a side view of the earth. I know it looks like a confetti bomb, but bear with me. Each sphere has exactly 5 rays coming from it, corresponding to 5 major stars. The colored rays are emitted by each sphere at the exact same angle relative to the north (red) side of the sphere. The spheres and rays are each rotated to match the latitude that they are located at.


Figure A: Side view of exploding spheres and guide particles rotated according to latitude

[continued]
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #9 on: February 14, 2017, 03:26:37 PM »

Terminology

Celestial Shell: Opaque, spherical shell surrounding the earth. Holes in this shell allow light to leak through. The radius of the shell is much, much greater than the size of the earth.
Guide Particle: Particle emitted by the exploding spheres that drilled holes in the celestial shell. Each location on earth had a guide particle corresponding to every star.
Exploding Sphere: The sphere that explodes and emits guide particles in identical directions. Rotation based on latitude.

Latitude: For this flat earth model, latitude corresponds with a radial distance away from North Pole. Each degree corresponds to the same distance as it does on the globe earth.
Longitude: Angle relative to the Prime Meridian, just like on the globe earth.

Declination: The latitude of the stars for a globe earth, measured from the equatorial plane.
Right Ascension: The longitude of the stars for a globe earth, measured from the vernal equinox (towards Aries).

For the flat earth model Right Ascension and Declination corrospond to the direction that each guide particle is emmitted from the unrotated exploding spheres.

Sidereal Time: The earth is rotating relative to the stars, obviously. Sidereal time is a measurement of time based on the rotation of the stars, rather than the sun. Tells us which direction the earth is facing relative to the vernal equinox.
Greenwich Mean Sidereal Time (GMST): The direction that the Prime Meridian of the earth is facing relative to the vernal equinox. Allows us to correlate earthly longitude with the right ascension of the stars.


The Math

The key to demonstrating this model's plausibility, is to show that the above explanation results in the correct azimuth and altitude of the the stars for any time and location on earth.

Given:

1. A star's right ascension and declination.
2. A latitude and longitude of a location on earth.
3. A time, converted to GMST.

Step (1) Use the right ascension and declination of the star to define an unrotated direction for the guide particle. Store the direction as a 3D vector.
Step (2) Use the location's longitude and GMST to rotate the vector towards the North Pole according to the location's latitude. This vector should now point towards the apparent location of the star.
Step (3) Calculate the altitude and azimuth of the vector on a flat earth.

Following the above steps does indeed result in the correct azimuth and altitude for any given star, location, and time, as shown by the provided simulation. Specifically, the simulation demonstrates predicting the azimuth and altitude for four stars in the Octans Constellation from Perth, Rio de Janeiro, and Cape Town, to more than 1 degree of accuracy, as requested in the challenge.
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #10 on: February 14, 2017, 03:28:34 PM »
The Simulation

Download the code from GitHub.

All of the above steps are accomplished in the provided file [flat.py]. If you want to know how it works, I recommend looking at the source directly with syntax highlighting. But I will copy the relevant bits here for completion's sake. Line numbers subject to change.

Step (1) starts on line 45 in [flat.py]:

Code: [Select]
    def base_ray_direction(self):

        direction = Vector3(0,1,0) # starts pointing towards the Y axis and vernal equinox
        direction.rotateX(self.dec.rad()) # declination rotation around X axis
        direction.rotateZ(self.ra.rad()) # right ascension rotation around Z axis

return direction

Step (2) starts on line 58 in [flat.py]:

Code: [Select]
    def local_ray_direction(self, location, gmst):

        direction = self.base_ray_direction() # get base vector
        lst = self.local_sidereal_time(location, gmst).rad() # calculate sidereal time for given location

        direction.rotateZ(-lst) # rotate to align the longitude with the Y axis to allow easy rotation
        direction.rotateX(math.pi/2.0 - location.lat.rad()) # rotate around X axis, towards north pole based on latitude
        direction.rotateZ(lst) # undo previous rotation to unalign with Y axis

return direction

Step (3) starts on lines 78 in [flat.py] for altitude:

Code: [Select]
    def altitude(self, location, gmst):

        direction = self.local_ray_direction(location, gmst) # guide vector

        return Angle(math.asin(direction.z / direction.length()))

And line 89 in [flat.py] for azimuth:

Code: [Select]
    def azimuth(self, location, gmst):

        direction = self.local_ray_direction(location, gmst) # guide vector

        absolute_direction = 0 # initialize to zero

        # avoid divide-by-zero errors
        if direction.x == 0:
            if direction.y > 0:
                absolute_direction = math.pi/2
            else:
                absolute_direction = -math.pi/2
        else:
            # calculate direction relative to global coordinate system
            absolute_direction = math.atan(direction.y/direction.x)

        # arctan() range is limited to -90 to 90 degrees. To detect 90 to 270 degrees, test sign of x component.
        if direction.x < 0:
            absolute_direction += math.pi

        # adjust angle relative to direction of North Pole. Towards North Pole should be zero degrees.
        azimuth = gmst.rad() + location.lon.rad() - math.pi/2 - absolute_direction

        # normalize azimuth to range of 0 to 360 degrees
        if azimuth < 0:
            azimuth -= int(azimuth/math.pi/2.0 - 1)*math.pi*2.0
        if azimuth >= math.pi*2:
            azimuth -= int(azimuth/math.pi/2.0)*math.pi*2.0

        return Angle(azimuth)

The Result

Code: [Select]
GMST: 4h 2m 28.0481977458s

rio:
delta_oct:
globe: Az/Alt: 182° 14' 8.16945010277" /17° 0' 23.2793430696"
flat:  Az/Alt: 182° 14' 8.16945010288" /17° 0' 23.2793430696"
nu_oct:
globe: Az/Alt: 191° 30' 39.9641734517" /30° 20' 49.4339413289"
flat:  Az/Alt: 191° 30' 39.9641734518" /30° 20' 49.4339413289"
beta_oct:
globe: Az/Alt: 185° 49' 29.3377905984" /29° 52' 39.4527891844"
flat:  Az/Alt: 185° 49' 29.3377905985" /29° 52' 39.4527891844"
theta_oct:
globe: Az/Alt: 184° 35' 35.7804448498" /35° 18' 6.116723158"
flat:  Az/Alt: 184° 35' 35.7804448499" /35° 18' 6.116723158"


perth:
delta_oct:
globe: Az/Alt: 174° 53' 26.5083250361" /36° 34' 43.6337723387"
flat:  Az/Alt: 174° 53' 26.5083250362" /36° 34' 43.6337723386"
nu_oct:
globe: Az/Alt: 173° 6' 45.755684795" /20° 51' 23.5551479106"
flat:  Az/Alt: 173° 6' 45.755684795" /20° 51' 23.5551479106"
beta_oct:
globe: Az/Alt: 177° 37' 2.84549070348" /23° 30' 19.1594183771"
flat:  Az/Alt: 177° 37' 2.84549070348" /23° 30' 19.159418377"
theta_oct:
globe: Az/Alt: 180° 58' 40.6675376947" /18° 57' 23.613682431"
flat:  Az/Alt: 180° 58' 40.6675376947" /18° 57' 23.613682431"


cape_town:
delta_oct:
globe: Az/Alt: 175° 14' 33.9679261964" /29° 8' 57.1516169648"
flat:  Az/Alt: 175° 14' 33.9679261965" /29° 8' 57.1516169648"
nu_oct:
globe: Az/Alt: 193° 14' 5.03808523773" /28° 12' 2.92270096098"
flat:  Az/Alt: 193° 14' 5.03808523773" /28° 12' 2.92270096099"
beta_oct:
globe: Az/Alt: 190° 14' 41.8928838067" /32° 24' 51.9823178602"
flat:  Az/Alt: 190° 14' 41.8928838067" /32° 24' 51.9823178602"
theta_oct:
globe: Az/Alt: 195° 44' 34.2066908047" /35° 31' 58.5052555279"
flat:  Az/Alt: 195° 44' 34.2066908047" /35° 31' 58.5052555279"

As you can see, the model correctly predicts the azimuth and altitude for the Octans Constellation from Perth, Rio de Janeiro, and Cape Town. The azimuth and altitude were calculated for the globe using standard (admittedly nasty) spherical trigonometry. You can compare these values with Stellarium if you wish. Make sure to set the time/date corectly. The above simulation was run at about 2016/11/5 01:05:00 UTC.

[Fin]
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

*

JackBlack

  • 26157
  • +51/-79
Re: Southern cross
« Reply #11 on: February 15, 2017, 12:36:05 AM »
A submission for aisantaros's challenge.

Download the code from GitHub.

* Please feel free to ask for clarification if something isn't clear *

Overview

This model demonstrates the possibility of accurately predicting the location of any star from any location on a flat earth, specifically, the Octans Constellation.

The earth is surrounded by a large "celestial shell", which is normally opaque to visible light. There are numerous holes in the celestial shell, which allows directional light to penetrate the shell and reach the earth. Each hole corresponds to a specific star seen at a specific spot on earth. For each star, there is exactly one hole in the celestial shell that allows a ray of light to hit a specific spot on earth. Given a high enough resolution of the shell (which can be arbitrarily increased by increasing its radius and thickness), the non-continuous nature of the stars would go unnoticed. While this specific arrangement of directional holes seems improbable in the extreme, there is a plausible natural explanation for it, which will be explained in the next section. This plausible natural explanation can be demonstrated to result in the exact same arrangement of stars as what we would expect to see on a globe shaped earth.


Origin of Directional Holes in Celestial Sphere

Imagine a small sphere sitting at the North Pole of the earth. The sphere explodes. Particles are shot outwards in all directions. Once these "guide particles" hit the celestial shell, they drill holes in the shell. These holes allow light from outside the shell to shine back on the earth. Due to the thickness of the celestial shell, the light that penetrates the holes will be highly directional. In fact, the light will only hit the exact spot where the original small sphere exploded. If a person stands in the exact spot where the sphere exploded, he will be able to see light leaking through the numerous holes in the celestial shell. However, if he moves slightly to the side, those holes will disappear, and the sky will again be black.

Now imagine billions (or more) identical small spheres covering the surface of the earth in a single layer. Each sphere is completely identical in every way. When each sphere explodes, it will emit the exact same arrangement of guide particles as every other sphere.

However, each sphere is facing a slightly different direction. Each sphere is rotated towards the North Pole by an amount corresponding to its latitude. Whereas when a sphere at the North Pole explodes, it will shoot a "Polaris particle" straight up, a sphere at 45° north latitude will shoot its "Polaris particle" at an angle of 45°, resulting in a hole that can be seen at an altitude of 45°. The exact same altitude that Polaris would be expected to be seen at from a globe earth.

Likewise, each exploding sphere has its own "Sirius particle", "Betelgeuse particle", "Rigel particle", etc, which allows those stars to be seen from anywhere on earth.

This is roughly illustrated in figure A. This is a side view of the earth. I know it looks like a confetti bomb, but bear with me. Each sphere has exactly 5 rays coming from it, corresponding to 5 major stars. The colored rays are emitted by each sphere at the exact same angle relative to the north (red) side of the sphere. The spheres and rays are each rotated to match the latitude that they are located at.


Figure A: Side view of exploding spheres and guide particles rotated according to latitude

[continued]
So you have the entire volume of the dome (or at least everywhere man has been to) covered in spheres which all explode at the same time and are oriented just right.
That makes no sense at all, especially as the particles would be colliding with one another, and they would fall due to whatever equivalent they have for gravity, and you are missing all the holes below us.

*

napoleon

  • 913
  • +0/-0
  • The Earth is not round, nor flat. It is a Donut...
Re: Southern cross
« Reply #12 on: February 15, 2017, 01:30:59 AM »
A submission for aisantaros's challenge.

Download the code from GitHub.

* Please feel free to ask for clarification if something isn't clear *

Overview

This model demonstrates the possibility of accurately predicting the location of any star from any location on a flat earth, specifically, the Octans Constellation.

The earth is surrounded by a large "celestial shell", which is normally opaque to visible light. There are numerous holes in the celestial shell, which allows directional light to penetrate the shell and reach the earth. Each hole corresponds to a specific star seen at a specific spot on earth. For each star, there is exactly one hole in the celestial shell that allows a ray of light to hit a specific spot on earth. Given a high enough resolution of the shell (which can be arbitrarily increased by increasing its radius and thickness), the non-continuous nature of the stars would go unnoticed. While this specific arrangement of directional holes seems improbable in the extreme, there is a plausible natural explanation for it, which will be explained in the next section. This plausible natural explanation can be demonstrated to result in the exact same arrangement of stars as what we would expect to see on a globe shaped earth.


Origin of Directional Holes in Celestial Sphere

Imagine a small sphere sitting at the North Pole of the earth. The sphere explodes. Particles are shot outwards in all directions. Once these "guide particles" hit the celestial shell, they drill holes in the shell. These holes allow light from outside the shell to shine back on the earth. Due to the thickness of the celestial shell, the light that penetrates the holes will be highly directional. In fact, the light will only hit the exact spot where the original small sphere exploded. If a person stands in the exact spot where the sphere exploded, he will be able to see light leaking through the numerous holes in the celestial shell. However, if he moves slightly to the side, those holes will disappear, and the sky will again be black.

Now imagine billions (or more) identical small spheres covering the surface of the earth in a single layer. Each sphere is completely identical in every way. When each sphere explodes, it will emit the exact same arrangement of guide particles as every other sphere.

However, each sphere is facing a slightly different direction. Each sphere is rotated towards the North Pole by an amount corresponding to its latitude. Whereas when a sphere at the North Pole explodes, it will shoot a "Polaris particle" straight up, a sphere at 45° north latitude will shoot its "Polaris particle" at an angle of 45°, resulting in a hole that can be seen at an altitude of 45°. The exact same altitude that Polaris would be expected to be seen at from a globe earth.

Likewise, each exploding sphere has its own "Sirius particle", "Betelgeuse particle", "Rigel particle", etc, which allows those stars to be seen from anywhere on earth.

This is roughly illustrated in figure A. This is a side view of the earth. I know it looks like a confetti bomb, but bear with me. Each sphere has exactly 5 rays coming from it, corresponding to 5 major stars. The colored rays are emitted by each sphere at the exact same angle relative to the north (red) side of the sphere. The spheres and rays are each rotated to match the latitude that they are located at.


Figure A: Side view of exploding spheres and guide particles rotated according to latitude

[continued]
So you have the entire volume of the dome (or at least everywhere man has been to) covered in spheres which all explode at the same time and are oriented just right.
That makes no sense at all, especially as the particles would be colliding with one another, and they would fall due to whatever equivalent they have for gravity, and you are missing all the holes below us.
Besides, you would have different constellations for every location on earth...for example, in Europe you can see the big dipper and orion, but in Japan you shouldn't be able to see these with this theory, but instead you should see different constellations at those exact spots,which is not true.
most constellations or other sets of stars like Orion, the big dipper, pegasus, Leo, etc. can be seen from at least half the globe, depending on where in the sky it is located.
Never argue with an idiot...
First they will drag you down to their own level,
and then they beat you by experience...

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #13 on: February 15, 2017, 01:55:18 AM »
I was just saying it is possible that we could see the stars in their actual location on a flat earth.

You gotta admit it's good.

We miss you totes.
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

*

JackBlack

  • 26157
  • +51/-79
Re: Southern cross
« Reply #14 on: February 15, 2017, 02:05:53 AM »
I was just saying it is possible that we could see the stars in their actual location on a flat earth.

You gotta admit it's good.

We miss you totes.
I prefer the simpler way. Just distort space so a flat Earth behaves exactly like a round Earth would in flat space.

*

napoleon

  • 913
  • +0/-0
  • The Earth is not round, nor flat. It is a Donut...
Re: Southern cross
« Reply #15 on: February 15, 2017, 03:42:42 AM »
I was just saying it is possible that we could see the stars in their actual location on a flat earth.

You gotta admit it's good.

We miss you totes.
I prefer the simpler way. Just distort space so a flat Earth behaves exactly like a round Earth would in flat space.
round earth in a flat space...I wouldn't even know how to imagine that... ??? ::) :-[
Never argue with an idiot...
First they will drag you down to their own level,
and then they beat you by experience...

*

JackBlack

  • 26157
  • +51/-79
Re: Southern cross
« Reply #16 on: February 15, 2017, 03:47:25 AM »
I was just saying it is possible that we could see the stars in their actual location on a flat earth.

You gotta admit it's good.

We miss you totes.
I prefer the simpler way. Just distort space so a flat Earth behaves exactly like a round Earth would in flat space.
round earth in a flat space...I wouldn't even know how to imagine that... ??? ::) :-[
Reality.

Flat space means that the sum of the internal angles of a triangle are 180 degrees, parallel lines remain the same distance, etc.
It is the space most people are used to.

*

napoleon

  • 913
  • +0/-0
  • The Earth is not round, nor flat. It is a Donut...
Re: Southern cross
« Reply #17 on: February 15, 2017, 03:59:24 AM »
I was just saying it is possible that we could see the stars in their actual location on a flat earth.

You gotta admit it's good.

We miss you totes.
I prefer the simpler way. Just distort space so a flat Earth behaves exactly like a round Earth would in flat space.
round earth in a flat space...I wouldn't even know how to imagine that... ??? ::) :-[
Reality.

Flat space means that the sum of the internal angles of a triangle are 180 degrees, parallel lines remain the same distance, etc.
It is the space most people are used to.
still not following you...but hey, whatever rocks your boat dude...
Never argue with an idiot...
First they will drag you down to their own level,
and then they beat you by experience...

*

disputeone

  • 27998
  • +109/-92
  • Or should I?
Re: Southern cross
« Reply #18 on: February 15, 2017, 05:58:49 AM »
Its like when they say the universe is flat, they mean euclidean, that you can use trigonometry to calculate distances.
A triangle with sides 3 and 4 and an angle of 90° will have a third side of 5 etc.

An example of non euclidean space would be the surface of a sphere.
Why would that be inciting terrorism?  Lorddave was merely describing a type of shop we have here in the US, a bomb-gun shop.  A shop that sells bomb-guns.

*

napoleon

  • 913
  • +0/-0
  • The Earth is not round, nor flat. It is a Donut...
Re: Southern cross
« Reply #19 on: February 15, 2017, 06:32:43 AM »
got it.
thanks dispute
Never argue with an idiot...
First they will drag you down to their own level,
and then they beat you by experience...