1. Abishua

    Abishua Member

    I heard a statement and not sure how to verify it, so asking here. So the statement is that from lets say 40 degrees north lat you can see all the northern constellations from any longitude, but the same is not true if you are at -40 degrees lat.. or southern hemisphere. So at south at that latitude you cannot see all the southern constellations like you can see all the northern ones from the north lat.

    Is this true or bunk?
  2. Henk001

    Henk001 Active Member

    Its bunk.
    The northern and southern hemisphere are completely symmetrical. As soon as you cross the equator you will be able to see the whole southern hemisphere (with the south celestial pole initially on the horizon and all the constellations circling around it).
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  3. Henk001

    Henk001 Active Member

    (Amateur) astronomers all over the world use Stellarium. Try it. Choose any location you like and watch what is visable.
    Don't worry about the fact that it is a computer program. Those amateur astronomers would immediately notice if things were wrong
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  4. Abishua

    Abishua Member

    Yes.. I was just looking at stelarium for the past hour or so.. to put it more clearly, the claim is that from all meridians at the equator simultaneously you can see ursa minor, major and polaris when looking north, but when looking south you cannot see simultaneously from all of them the south pole star and southern cross constellation.
  5. Trailspotter

    Trailspotter Senior Member

    No, it is not possible to see Ursa Major from all meridians at the Equator simultaneously. However, it is possible to see both Ursa Major and Crux (Southern Cross) from the Equator simultaneously, just not all time. I actually have seen them both simultaneously from Amboseli NP, Kenya, 2.5° south of the Equator.
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  6. Mick West

    Mick West Administrator Staff Member

    This type of claim dates back to Samuel Rowbotham, and is repeated by modern Flat Earth promoters. It was very hard to check back in the 1800s, but is very easy to check now.

    Here's an example from Dubay's book, and his supporting quotes:

    Totally wrong. the latitudes a star is visible from depends only on its declination, equivalent to latitude in the celestial sphere (and maybe a couple of degrees due to refraction at the horizon). So Polaris, at 89° can only be viewed down to 2 or 3 degrees below the equator (under ideal viewing conditions).

    Dubay seems to be repeating a misconception that the tilt of the Earth allows the stars to be seen. The tilt of the earth is only relevant to the Solar System, the axis of the the Earth points in a relatively fixed position year to year, and the pole stars are just the stars closest to the point where the axis happens to point.

    Again, the visibility of any star is directly related to the its declination. The star in Ursa Major closest to the celestial North Pole is the amusingly named Dubhe, which has a declination of about 61.5° So from 30° South, at it's highest, Dubhe still fails to rise above the horizon (unless refraction bumps it up a degree or so). Here's the view showing the horizon. This intermittent visibility of (most of ) Ursa Major is entirely expected and very straightforward.
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  7. Henk001

    Henk001 Active Member

    Last edited: May 18, 2017
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  8. Amber Robot

    Amber Robot Member

    Further, it is very easy to show with simple trigonometry that in Dubay's model the elevation angle of Polaris as a function of latitude doesn't agree with reality, disproving his flat earth model. He may mention observability, but he doesn't mention the actual angles they're observed at.
  9. Mick West

    Mick West Administrator Staff Member

    This all related to the "Ground Truth" idea I wrote about here:
    Stellarium matches observed reality. Stellarium shows a round Earth. Case closed.
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  10. Abishua

    Abishua Member

    Thanks for all your responses.. lovely picture Henk! if some people from equator do not provide photographic evidence of this I agree.. case closed.
  11. Rory

    Rory Active Member

    There is another factor in this, which I discovered when challenged by a flat earther that he had evidence that Polaris could be seen from below 3°S - that of elevation.

    It turns out he was right: but the image he was citing was taken from Kilimanjaro, at over 19,000 feet above sea level - an elevation which would give a view, by rough calculations, something similar to what would be seen from about 182 miles, or 2.7 degrees, further north.

    Not sure if there are any mountains further south than that from which Polaris could be seen. All the big ones in Ecuador are a little closer to the equator. And, of course, that still leaves another 86.9 degrees worth of globe from which the north star can't be seen.