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GaryN
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18 Apr 2017 22:40

I was reading about William Herschel the astronomer, and he believed that it was only Earths atmosphere that made the stars, planets and even the Sun visible from Earth, and that outside of an atmosphere of sufficient density and composition, nothing is visible, and that even the heat we feel is generated by the atmosphere. I am wondering then what the views of the Sun in the simulator are based on, as there are no actual photographs of the Sun from outside of Earths atmosphere, and none were taken by the Apollo crews while in cislunar space.
The program itself is brilliant, though I need a much newer computer to run it decently, but I am concerned that the model of the Sun might not be correct.
 
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19 Apr 2017 03:44

There are plenty of images of the Sun taken by the Hubble Space Telescope and by several missions which had precisely the Sun as a primary target, covering the spectrum from infrared emissions to high energy X-rays and visual lightwaves as well.
Here's a list of past, current and future missions: http://www.planetary.org/explore/space- ... e-sun.html
No human being took directly visual photos because there were no favorable conditions. Even people in ISS can't do that because they're moving too fast.
As far as I know, please someone correct me if I'm wrong, SE model of the Sun is based on algorithms mimicking as much as possible visuals and mathematical simulations based on stellar evolution theories.
Its appearance is tuned from time to time, and sunspots have a slight unnatural feeling, but it's a work in progress. Right now a new approach is being evaluated which could change for the better the rendering of many objects, stars included in due time.

William Herschel was a great astronomer, I didn't know he believed that, but according to data we have he was wrong :)
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19 Apr 2017 04:24

GaryN wrote:
Source of the post I was reading about William Herschel the astronomer, and he believed that it was only Earths atmosphere that made the stars, planets and even the Sun visible from Earth, and that outside of an atmosphere of sufficient density and composition, nothing is visible, and that even the heat we feel is generated by the atmosphere.

Never heard that before -- if it's true that's pretty interesting.  

Of course, Herschel lived ~200 years ago.  Today we have a robust theory of electromagnetism, Maxwell's equations, and an understanding that light propagates through a vacuum unimpeded.  Indeed, you can say that the vacuum is the most natural medium for light to propagate in.

So understanding the appearance of stars and our Sun from outside of the atmosphere is actually pretty simple, and there are abundant space-based observations to go from.  You can find photographs containing the Sun from Apollo missions, the Shuttle and ISS footage, as well as images specifically intended to study the Sun from dedicated observational platforms like SOHO.

Visually, the Sun from outside the atmosphere looks like a blindingly bright white orb, and similarly in photographs.  A photograph exposed to capture details on its surface will reveal sunspots, and in other wavelengths other details of the solar atmosphere become apparent.
The effect of the atmosphere is to dim and redden the light by absorption and scattering, and the atmosphere also refracts the light slightly (you can actually still see the Sun when it is geometrically below the horizon, which is pretty neat).

Mosfet wrote:
Source of the post SE model of the Sun is based on algorithms mimicking as much as possible visuals and mathematical simulations based on stellar evolution theories.

Basically yes.  All important properties of a star are determined by their initial mass and age, so SE uses results of stellar evolution models to determine their appearance.  The color and brightness is based on the physics of a blackbody spectrum (color and brightness are a function of temperature, with hotter surfaces being brighter and peaking in shorter wavelengths).
 
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19 Apr 2017 11:46

Mosfet wrote:
There are plenty of images of the Sun taken by the Hubble Space Telescope and by several missions which had precisely the Sun as a primary target, covering the spectrum from infrared emissions to high energy X-rays and visual lightwaves as well.



No, Huibble was not designed to do that. SOHO can image the Sun ar wavelengths our eyes can not see, but has no conventional camera. I asked the boffins at a military R&D facility how we could see the true colour of the Sun from space, and they said by using a Neutral Density filter, as it reduces all wavelenght equally. 
 Lots of images of the Sun through ND filters taken from Earth, but I can find none from space. Images of the Sun taken from the ISS or Apollo missions when in Earth orbit do not use filters, and they took no solar filters on the Apollo missions and do not have them as standard equipment on the ISS. Don Pettit had to take his own filter to image the Venus transit of the Sun, but from the Cupola, the line of sight to the Sun was through Earths atmophere, and not looking away from Earth, which they can not do from the Cupola. There are no portholes facing away from Earth on the ISS, or none that are in use anyway.
 I came by Space Engine while looking for video of the Cupola location when seen from outside of the ISS. Here is a screenshot from the SE video, and one from the ESA simulation.
http://www3.telus.net/myworld/SE_cupola.png
http://www3.telus.net/myworld/cupola.png 
You can see that the view is very restricted, and is limited to a line of sight which must pass through Earths atmosphere. Yes, the atmosphere is thinner up there, but the column of atmosphere the LOS passes through is much deeper than the LOS we see through when looking away from Earth, as illustrated in this graphic.
http://www3.telus.net/myworld/los4.jpg
Techically, the atmosphere goes out much further, so even if a line of sight out to 90 degrees from the perpendicular (Earth facing) window, they would still be looking through a very deep column of atmosphere. It is a forward scatter process of UV/EUV light from the Sun that creates a beam of visible light that we see from Earth, so the atmosphere is acting as a kind of optical transformer.
 They did take images of the Sun from the lunar surface, and the Moon supposedly has no atmosphere, but the LADEE mission showed that there is an atmosphere of nanometer sized dust grains, and it is known that these dust grains when subject to UV/EUV light will produce a white, full spectrum light, which is what illuminated the astronauts quite brightly when the centre of the beam was passing over their location. The low level light, Earthshine as we call it, is actually due to the UV/EUV from the top of Earths atmosphere interacting with that fine dust lunar atmosphere. There are no photos of the Sun itself from lunar orbit though.
The Sun from the lunar surface is much larger than it should be with the lens they were using, and that is put down to camera optics, but I think this is actually how the Sun appeared to their eyes. So if the Sun is visible in space, as NASA claims, why were no photos of it taken during 3 days each way in Cislunar space with nothing much else to do?
Sorry to ramble on, and I am in no way knocking SE, but rather believe it could be used to demonstrate the inconsistencies in NASAs photos and explanations. Of course space travel would be very boring if the only time you could see anything was when you were close enough to a planet with an atmosphere sufficient to create the light that illuminates the planet, or to be able to look through its atmosphere to see the stars, as they do from the ISS. In the original Star Trek series, the bridge had no windows, everything was displayed on large screens, and those images would be from instruments which can see what our eyes could not, and that is likely exactly how it would have to be. As Herschel said, the light in space is not suitable to human vision.
Thanks for listening to my theory, and congratulations on producing such a wonderful piece of software.
   
 
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GaryN
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19 Apr 2017 11:50

The link to the line of sight graphic in my post should have been:
http://www3.telus.net/myworld/iss_los4.png
Couldn't edit my post.
 
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19 Apr 2017 15:03

GaryN wrote:
Source of the post No, Huibble was not designed to do that.

Sorry, I forgot to place a comma where it counts, but Hubble obviously is a multi-purpose mission.
Could you please post a reference about Herschel's point of view you cited in your first post, I can't find any source.
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19 Apr 2017 15:54

Mosfet wrote:
GaryN wrote:
Source of the post No, Huibble was not designed to do that.

Sorry, I forgot to place a comma where it counts, but Hubble obviously is a multi-purpose mission.
Could you please post a reference about Herschel's point of view you cited in your first post, I can't find any source.
In this case, radiant heat will at least partly, if not chiefly, consist, if I may be permitted the expression, of invisible light; that is to say, of rays coming from the sun, that have such a momentum as to be unfit for vision. And admitting, as is highly probable, that the organs of sight are only adapted to receive impressions from particles of a certain momentum, it explains why the maximum of illumination should be in the middle of the rays; as those which have greater or less momenta are likely to become equally unfit for the impression of sight.

"In this case, radiant heat will at least partly, if not chiefly, consist, if I may be permitted the expression, of invisible light; that is to say, of rays coming from the sun, that have such a momentum as to be unfit for vision. And admitting, as is highly probable, that the organs of sight are only adapted to receive impressions from particles of a certain momentum, it explains why the maximum of illumination should be in the middle of the refrangible rays; as those which have greater or less momenta are likely to become equally unfit for the impression of sight."
Here he was talking about heat being from light which is not suitable for vision, but his principle applied also to light with a higher velocity, what we would not call  UV and up. 
However, looking a bit more at what he said, I may be putting words in his mouth, as in this statement he did say the Sun had a bright outer layer:
"According to Herschel, the sun consisted of three essentially different parts. First, there was a solid nucleus, non-luminous, cool, and even capable of being inhabited. Second, above this was an atmosphere proper; and, lastly, outside of this was a layer in which floated the clouds, or bodies which gave to the solar surface its intense brilliancy."
So his model was also rather non-conventional, and perhaps he did not mean that the light from the Sun was of a higher velocity than that of visible light, and that visible light was converted to IR in the atmosphere. We now know from Apollo though that stars and galaxies can be seen from the Lunar surface in far UV, as seen from the FUVC device. Why they couldn't have used one of their cameras from the shaddow of the lander to photograph them on visible light at the same time, I don't know.
http://www3.telus.net/summa/faruv/explain.htm
Without an atmosphere similar to Earths to convert the UV to visible, I don't think stars will ever be imaged from the Lunar surface. Certainly the Chang'e lander camera is capable of astrophotography, but if stars are visible, then the Chinese have never made them available. Anyway, all I have ever wanted of NASA is to perform some experiments, empirical science, to determine what is and is not visible from clear space, but they won't do it.
Well, actually they did, from the Apollo missions, a low light photography experiment, using long exposures (up to 3 minutes) with military spec. film, and the images are available.
https://archive.org/details/as16-125-19932
Perhaps there was a malfunction of the camera or film?
According to Herschel, the sun consisted of three essentially different parts. First, there was a solid nucleus, non-luminous, cool, and even capable of being inhabited. Second, above this was an atmosphere proper; and, lastly, outside of this was a layer in which floated the clouds, or bodies which gave to the solar surface its intense brilliancy.
According to Herschel, the sun consisted of three essentially different parts. First, there was a solid nucleus, non-luminous, cool, and even capable of being inhabited. Second, above this was an atmosphere proper; and, lastly, outside of this was a layer in which floated the clouds, or bodies which gave to the solar surface its intense brilliancy.
 
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19 Apr 2017 16:00

Where is the edit button?
In my previous post it should read "what we now call UV and up", not "not".
 
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19 Apr 2017 16:32

GaryN wrote:
Without an atmosphere similar to Earths to convert the UV to visible

Sorry, what?!
Where did even got something like that? Unless I'm missing something, air isn't capable of magically doing that conversion. UV is almost completely blocked by it.
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19 Apr 2017 16:38

GaryN wrote:

Here there's a more complete catalog: http://www.lpi.usra.edu/resources/apoll ... ission/?16
Given the light reflection of the surface and the over-saturation of the Earth in those Hasselblad images, not counting the fact that I believe those Hasselblad had fixed focus, I don't think it's particularly surprising the absence of pointed light sources like stars in those films.
It seems on the other hand that other images where taken during the passage of the command module over the dark side, where they did caught some stars, Sirius among others:
http://tothemoon.ser.asu.edu/gallery/ap ... -127-19997
http://onebigmonkey.com/apollo/stars/ap16bstars.html

Edit:
Someone confirmed me that Hasselblad used in those missions had manual focus. Inside the module they used a Nikon.
Last edited by Mosfet on 20 Apr 2017 05:29, edited 2 times in total.
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20 Apr 2017 09:37

XBrain130:

air isn't capable of magically doing that conversion. UV is almost completely blocked by it.



And what happens to that blocked UV? It doesn't just disappear, conservation of energy. Some molecules in the upper atmosphere will emit IR for up to 5 minutes when struck by UV, so in effect is being transformed. 

Watsisname:

Your idea also predicts that all space-based astronomy is useless, because the stars would be invisible.  So not only must NASA be in on the conspiracy, but every space agency, and every astronomer and astrophysicist.



Space based astronomy at visible wavelengths is an odd situation. I don't understand why only NASA can do it, and that no other space capable nation has a space based telescope. Hubble is a very complex instrument, not just a telescope with a camera at the focal plane, as has been proposed by a couple of astronomy groups, but which have never made it to orbit:

Testbed Paves Way for Amateur Space Telescope
http://www.skyandtelescope.com/astronom ... telescope/

Vintage Micro: The Amateur Space Telescope
http://www.drewexmachina.com/2014/04/16 ... telescope/


It seems to me that your idea predicts that the intensity of visible illumination on an object would be a function of altitude, decreasing in relation to the atmosphere's scale height. 



No experiments have been performed to determine the intensity and wavelengths of light with increasing altitude, or to determine what is visible while looking directly away from Earth while ascending to orbit. The Zenith facing external platform on the ISS would make an excellent astronomy location, but there has never been utilised for such. Video astronomy would seem to be the ideal option there, the stars/planets scrolling by in real time, but that idea has been rejected too. 

Mosfet, yes stars would be visible, under certain circumstances, but I wonder why we have never seen the heavens from Apollo as they appear from a Nikon film camera strapped to the main telescope of a jet flying at 40,00 feet?
https://mainweb-v.musc.edu/cando/haley/apod/apod.html
from:
https://mainweb-v.musc.edu/cando/haley/haley00.html

Watsisname, I have studied nearly all the instruments sent on various missions in space, and am also familiar with the methods of light creation and propagation and attenuation, and all space based instruments now rely on spectral processes, not film or Bayer filtered digital imaging. But you are correct, I probably should post in the conspiracy forum, as until I see some hard science being performed, I am very suspicious of much of what NASA tells us about what is going on out there, and my suspicions are due just as much to what NASA has NOT shown us as what they have shown.
 
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20 Apr 2017 10:24

GaryN wrote:
Source of the post I don't understand why only NASA can do it, and that no other space capable nation has a space based telescope.

Maybe because USA is about the only nation that can afford pouring billions of dollars into making one?

Also, they let other parties take turns at using it, so what's the point of wasting money building another?

GaryN wrote:
Source of the post but I wonder why we have never seen the heavens from Apollo as they appear from a Nikon film camera strapped to the main telescope of a jet flying at 40,00 feet?

idk, my guess is because they moved too fast to focus on stars, or because they were too busy, who knows, trying to land on that big rock ball they were there for in the first place
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20 Apr 2017 12:50

Maybe because USA is about the only nation that can afford pouring billions of dollars into making one?


I am  told that a large Celestron 'scope would perform  almost as well as Hubble, cameras are relatively cheap, India can put things in space pretty cheaply, so where's the Billon$ come from? Sun sensors and star trackers (for navigation/orientation) getting less expensive, but even so, a crowd sourcing effort for a "peoples telescope" might gain interest? 
 
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20 Apr 2017 12:58

GaryN wrote:
Source of the post I am  told

..by who? I just happened to start following a certain guy who goes as CoolHardLogic on YouTube and dedicates himself to debunking the most stupid cospiracies, and this kind of sourceless claims are pretty common in those.
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20 Apr 2017 15:23

GaryN wrote:
Source of the post but I wonder why we have never seen the heavens from Apollo as they appear from a Nikon film camera strapped to the main telescope of a jet flying at 40,00 feet?

14 years of advancements in technology and science. And that Nikon ain't the same.
I wonder who had a Celestron with a 2.4 m mirror.
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