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4

Yes. The observer is "flipped". In northern hemisphere the sun in in the southern half of the sky. So the bottom of the sun is toward the south horizon. The top of the sun is toward the north. By convention this side is the north of the sun (or moon). When facing the sun (at noon) north is up toward the top of your head. In the southern hemisphere the ...


6

Yes, the orientation of the Sun will be different from the Earth's northern and southern hemisphere, just like your example of the Moon. I would not say that a sunspot in the "northern" hemisphere would appear to be in the "southern" hemisphere just because of the change in orientation. North is fixed on the Sun and Moon, just like they are on the Earth. (...


1

On the other hand the found materials (minerals / isotopes ) show clear evidence that the sun did NOT cross those spiral arms. Spiral arms as areas with higher star density pose the threat of super novae in close proximity. All we have found on earth leads to the conclusion that the earth - and with it the sun - never were closer than 30 light years to a ...


1

In most sundials, the gnomon is aligned with the Earth's polar axis so that the shadow indicates the Sun's hour angle. A vertical tower instead casts a shadow indicating the Sun's azimuth. The time of day can be computed from this, but simple hour marks won't quite do it. Let's try it with your photo. The Skytree is at 35.7°N, 139.8°E, and the ...


1

Anything which casts a shadow can become a sundial, as JH's comment points out. The other thing you need to know is the latitude of the building, as that affects the change in shadow direction per hour of elapsed time. Worse, due to the eccentricity of Earth's orbit (and rotation axis), there's an offset between clock time and sundial time which varies ...


43

What is a spiral arm? The reason that the Sun, in principle (but see below), may cross spiral arms is that galactic spiral arms are not rigid entities consisting of some particular stars; rather they are "waves" with a temporary increase in density. An often-used analogy is the pile-up of cars behind a slow-moving truck: At all times, all cars are moving ...


1

The "radius" of the Sun is basically where the optical depth to radiation at any particular wavelength is about 1 (or some times 2/3 is used). This is known as the photosphere and is from where the light that we measure comes from. The "thickness" of the photosphere - i.e. the depth over which the optical depth changes from being negligible to very large is ...


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