1. DavidB66

    DavidB66 Member

    It doesn't look as though all the stars are different distances
    I don't know about that. The main visual clues to the distance of the stars are their size and brightness. They differ conspicuously in brightness. We were discussing their apparent size on another thread. While they are commonly described as mere points of light, my own subjective impression is that when viewed with the naked eye (or in my case through glasses) the brighter stars form a small blurry patch, which is larger in some cases than others, and definitely larger than the fainter stars. To me, at least, some stars do look further away than others.

    A complication worth noting is that the fainter stars are only visible to peripheral vision. (It's something to do with rods and cones - I forget which is which!) I don't know when this was first noticed, and how people explained it without knowing anything about the structure of the eye.
     
  2. Neil Obstat

    Neil Obstat Member

    The difference between stargazing without a telescope, and with one, is so enormous it's beyond words.

    If you've never tried it, you're missing out: Just get a pair of binoculars and go out to the desert and find the darkest patch of black sky you can find with only your glasses on -- then see what it looks like through binoculars.

    Or look up an amateur astronomy club in your area, and show up at one of their viewing events. They'll have their telescopes all standing in a field or a parking lot, letting visitors take a peek and watch things moving in the sky (over time). You can ask them questions and their answers will amaze you. These are just amateurs and they have more awareness of the cosmos than the most prominent astronomers of antiquity.
     
    Last edited: Jun 9, 2018
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  3. DavidB66

    DavidB66 Member

    I agree that a telescope or binoculars make a big difference, but the model of the sky as a kind of hemispherical dome, with the stars scattered on its surface, and therefore at equal distances from an observer at the centre, predates the telescope by a few thousand years. Indeed, the dome model was beginning to go out just as telescopes were coming in!

    I can only say that I don't personally get an impression of the sky as a dome, whether by night or day, with or without aids to vision (I have binoculars). That may be partly because living in England I very seldom get a clear view of the whole sky at all! Maybe it looks more dome-like when viewed from a Mesopotamian desert. But I do wonder whether the dome model was entirely the product of naïve perception, or whether it was contaminated by religious and philosophical doctrines from the outset.
     
  4. Z.W. Wolf

    Z.W. Wolf Active Member

    Hard to say, but I've lived under the clear skies of the SW U.S. almost all my life and I intuitively see it as a dome. When I apply my knowledge and look at it analytically I do see it in 3D. E.g. when looking at the Milky Way in Cygnus I can visualize the stars as lights in a tunnel. (We're looking along the length of the Orion–Cygnus Arm.)
     
    Last edited: Jun 9, 2018
  5. Neil Obstat

    Neil Obstat Member

    From the outset, Mick, it seems to me you have a very good point here, however, when I anticipate the questions flat-earthers will ask, it seems to me that you have a number of gaps in your data. In order to "save time" I'd like to have the weak spots all covered. I have here some questions whose answers ought to go a long way to closing up those gaps!

    Where you have "just before sunrise in Sydney the sun has set in Santiago," that seems to be a mistake. In the "flat" earth model you show above, the sun rotates clockwise, from east to west. I can understand "Just before sunrise in Santiago the sun has set in Sydney," when the sun is passing Africa leaving the Indian Ocean, but you have the opposite of that, and it looks to me that with the sun still up over the Pacific, the sun would be about to rise in Sydney and Santiago would be in the late afternoon, e.g., not already set in Santiago, as you say. It appears to me that both Sydney and Santiago could have sunlight at the same time during the southern winter. However, if we would wait a few hours for the sun to pass the Indian Ocean, then it would definitely be past nightfall in Sydney and not yet sunrise in Santiago.

    If the important part is, "In the southern [hemisphere] winter the nights are long," then you ought to supply the time of sunset in Santiago AND the time of sunrise in Sydney for this day (June 21st, 2017), as well as the duration of night for both locations (which ought to be the same on the same day). You ought to give the UTC time difference and time zones AND you ought to provide the degrees longitude of each and their difference (in case the reader can't manage to subtract - but more importantly, to double check your data). Latitude would be nice but it's not as important as longitude.

    In these two photos of the Southern Cross, the time says 3:00:00 for each one. Does that mean the photos were taken at each location when it was 3:00 am local time (then they were not taken at the "exact same time" but at the exact same LOCAL time)?

    Since they are different time zones, if the photos were taken at literally the same exact moment the local times should be different by several hours (with their difference = UTC difference).
    Or, are these times "3:00:00 UTC" times? (You didn't say anything about UTC or GMT.)
    Or, are they both Santiago times?
    Or, are they both Sydney times?

    Also, the photos do not show the latitude and longitude of their locations, only the name of the city. If I were to add the longitude I might make a mistake.

    Sorry for all the questions, but reading the threads on Metabunk this is the kind of 3rd degree questioning you subject others to, so it ought to be no sweat for you to answer these.
     
    Last edited: Jun 10, 2018
  6. Whitebeard

    Whitebeard Senior Member

    thats what makes astronomy so cool, its about the only field of science left where a keen amatuer can be at the cutting edge of the field even today...

    I can't wait for this years solarsphere festival. My annual chance to go to a field with dark skies and get to look at cool things through some meaty telescopes. (Plus a chance to chill with cool people, check out some great bands and go to some very informative talks, lectures and workshops.
    http://www.solarsphere.events/
    Well worth the £45 weekend ticket price!!

    (sorry for the plug but it is a great and almost unique event that deserves as much support as possible)
     
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  7. Neil Obstat

    Neil Obstat Member

    Regarding my reply, above, to Mick West:

    Okay, so I didn't know you were using Stellarium. I just figured that out!
    I downloaded the free software and checked out Santiago, Chile, and Sydney, Australia, getting these data:

    Santiago: lat. S 33 37' 25" long. W 70 38' 54" Alt. 556m Date: 2018-6-10 (before IDL)
    Sydney: lat. S 33 52' 4.2" long. E 151 12' 26" Alt. 58m Date: 2018-6-11 (beyond IDL)

    Santiago TIME: 23:38 UTC -4 (23:38 + 4 = 3:38 am UTC)
    ...............................................................................................................................} These are both the same time.
    Sydney TIME: 13:38 UTC +10 (13:38 - 10 = 3:38 am UTC)

    I'm not sure how the settings work (why your times said 3:00:00 for both locations) but here I have two different times for Santiago and Sydney, and UTC -4 makes sense for Santiago, as does UTC +10 for Sydney, so those must be local times. It's about midnight in Santiago and it's daytime in Sydney (13:38 is 1:38 pm). The Southern Cross is visible in the sky using Stellarium showing about 12:30 Right Ascension in both locations, but in Santiago the Crux is on the right (west) side of the sky, while in Sydney the Crux is on the left (east) side of the sky.

    This makes sense on a globe, but it only makes nonsense on a "flat" earth.

    In effect, while the prominence of Crux in the sky makes it easy to see, and easy to understand its significance, the abiding principle behind the difference in orientation of the celestial southern hemisphere is amply shown by the fact that the Right Ascension hours are always precisely tied to a specific longitude on earth, that is, any given longitude has a one-to-one correspondence with just one rotary orientation of the hours in the equatorial grid, or dial position. (I might not be using the best terms here.) IOW once you recognize the orientation of the Right Ascension hour grid in the celestial sphere, you don't have to rely on the position of the Southern Cross and the time to inform you of your meridian. But it's a nice proof of your judgment to see the Crux in the night sky.

    In the worst case, I can imagine hearing flat-earthers whine that Stellarium is all fake. So then what do you say in that case? What do you say when they claim to have a friend in Sydney (or Santiago) who says the sky doesn't look like that at all at that time?

    BTW I found a very helpful site for understanding the basics of southern hemisphere astronomical terminology:

    https://nightinfocus.wordpress.com/category/constellations/southern-cross/
     
    Last edited: Jun 10, 2018
  8. Mick West

    Mick West Administrator Staff Member

    I'd say "demonstrate it".

    Stellarium has always been 99.999% accurate, as far as I know.
     
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  9. Astro

    Astro Active Member

    You can calculate the altitude/azimuth of a given set of right ascension and declination coordinates at a given location and time for yourself using relatively straight-forward equations that can be found in a variety of old astronomy books.
    sin(altitude)=(sin(declination)*sin(latitude))/(cos(declination)*cos(latitude)*cos(hour angle in degrees))
    cos(azimuth)=(sin(declination)-sin(latitude)*sin(altitude))/(cos(latitude)*cos(altitude))
    hour angle in degrees = (local sidereal time in decimal hours - right ascension in decimal hours)*15
    You can download an alt/az spreadsheet I created to do these kinds of calculations here:
    http://dropcanvas.com/xeo04
     
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  10. qed

    qed Senior Member

    I would appreciate references to your sources for the Egyptian cosmology. Not doubting (and as you say a long history) just interested.
     
  11. Z.W. Wolf

    Z.W. Wolf Active Member

    I'm interested in psychology, history and astronomy. The subject at hand is an intersection of all three. I've done so much reading over the decades... and I have no logbook. As a start, I'll to point to anything by John Romer. You have to grok the Egyptians first, because it's a completely different mindset. Although they mapped the sky in great detail, and had good predictive models, their cosmology was almost entirely religious in nature. Pre-scientific people were intuitive thinkers, and felt that everything was alive. The Egyptians felt that the earth and sky are alive and full of alive things.

    Here, on the ceiling of a tomb, is a bit of Egyptian cosmology. The two female figures are goddesses. Mut, the Earth Goddess, was considered a primal deity, associated with the waters of life from which everything was born. You can see the Sun Disk passing through her body. The figure with the stars in her body is Nut, the Sky Goddess.

    [​IMG]

    Before going any further... These paintings are not meant to be representational. Nut is associated with the dome of the sky, but the dome doesn't literally look like a woman. The sky is alive with her goddess spirit and will. The Sun and stars are alive things, inside her. The Underworld is a physical place, but infused with the aliveness of Mut. It's a vast place with the waters of life flowing through it Her.

    They seem to be back to back, but this is not meant to be their actual physical arrangement. We would think that the sky would be over the earth. We're running into an artistic practice. You'll see the same kind of thing on the ceiling of the tomb of Seti I. There you can see paintings of recognizable constellations, but it's confusing because they don't have the same physical relationship to one another you see in the sky.

    The Sun, or Amun-Ra the Sun God, or the Dead Pharaoh who has become Amun-Ra, journeys during the night on a boat on one of the Underworld rivers of the Waters of Life. There was no definite separation between the physical sun we see in the sky, the Sun God Amun-Ra (who himself is a fusion between two gods), and the Pharaoh(s) who become(s) Amun-Ra.

    If you're looking for a cosmology the way we think of it in analytical terms you might find yourself lost or even frustrated. (But in all of this, I'm working from memory and over-simplifying. It is best to really rely on your own education.)



    Most apropos to the subject of this thread, I'll reiterate: The cosmology of the Egyptians made intuitive sense based on what we see. The sun looks as if it is rising above an edge, passing over us, and dropping below an edge. It doesn't look as if it's traveling in a circle above the flat surface of earth.

    The night sky looks like a fixed dome with independent stars moving through it on fixed courses, some of which also dip below a physical edge and rise above a physical edge. It doesn't look like a rotating dome with fixed stars on its surface. That model doesn't make intuitive sense even to a person who doesn't travel. E.g. stars on the horizon would be moving sideways and parallel to the horizon.

    In both cases these modern FE models were invented because no one can now deny times zones.

    In both cases Modern FE Believers are not trusting their eyes; they have concocted pseudo-analytical rationalizations to explain away what we see.




    I can point to a book I read not too long ago.

    The History and Practice of Ancient Astronomy
    by James Evans



    A bit more about John Romer. He's a very good start because his love for these people is evident, and he explains how they lived... and thought... and felt. Just as different people/deities/things could fuse into one, each person had parts of himself, that would separate and go to different places after death.

    [​IMG]

    I've gone on here at Metabunk about the difference between analytical thinking and intuitive thinking. I don't want to give the impression that I hate intuitive thinking. It's the place where you feel, and grok what other people are all about. But when you use nothing but intuitive thought (especially if you are a suspicious person full of negative emotions) you can get into trouble.

    "Love with your heart, use your head for everything else."
     
    Last edited: Jun 11, 2018
  12. qed

    qed Senior Member

    You first describe Ancient Egypt where the writing that exists today was mainly carved into tombs or buried in tombs.

    You then refer to the "Egyptian model" as if the aforementioned is indeed this model.

    The "Egyptian System" is quite different.

    Not yet 100% correct (sun rotating about earth), but certainly not a flat earth.

    http://history.wikia.com/wiki/Spherical_Earth
     
    Last edited: Jun 11, 2018
  13. Z.W. Wolf

    Z.W. Wolf Active Member

    Edit: I really can't expend any more energy on this, nor should I, because we're drifting too far away from topic. So this will be it.

    I'm talking about beliefs during the New Kingdom, (c. 1550 BC – c. 1077 BC), many hundreds of years before Aristotle.

    You've pasted in something that comes from a philosophical work - Commentary on the "Dream of Scipio" - written during the Later Roman Egypt Period (4th–6th centuries CE). Note the part I've bolded. Theodosius connected this model of the cosmos, through personal speculation or wishful thinking or whatever, quite wrongly, to ancient Egypt.

    Egyptian pharaoh Necho II, reigned from 610 BCE to 595 BCE - still quite a long time after the New Kingdom. The ultimate source of this tale comes from Herodotus:

    Which as far as I know doesn't mention anything about cosmology.

    From Wikipedia

     
    Last edited: Jun 11, 2018
  14. qed

    qed Senior Member

    Perhaps just edit your post to reflect that you are referring only to New Kingdom Egypt. Egypt has a very long history.
     
  15. qed

    qed Senior Member

    The sun that they had always seen to the south (all being from the Northern hemisphere) was now to the north!

    While Herodotus, Strabo, Polybius, and Ptolemy doubted that this could be possible, they were all wrong to doubt. The unbelievable thing the sailors reported is exactly what should have happened.