is APOD Nov 14th a fake?

[Guest]

The sky shows all the stars rotating around a tower. Wouldn't that only occur in two places on earth (the two poles)? Everywhere else, they'd travel in some kind of arc and straight at the equator.

[BMAONE]

THIS EFFECT OCCURS EVERYWHERE (AS FAR AS I KNOW). IT IS TRUE THAT THE STARS WOULD APPEAR TO TRAVEL IN A STRAIGHT LING AT THE EQUATOR, BUT ONLY THOST STARS DIRECTLY OVERHEAD. AS YOUR LINE OF SIGHT TRAVELS NORTHWARD OR SOUTHWARD THE STARS SEEMINGLY TRAVEL IN ARCS. THE FARTHER NORTH OR SOUTH YOU TRAVEL (I'M AT APPROX LATITUDE 38 NORTH) YOU SEE THE POLAR STARS. ALL VISUAL REFERENCE ROTATES AROUND THESE STARS. SO IF YOU SEE POLARIS (THE NORTH STAR) FROM MY LATITUDE, THE STAR FIELD APPEARS TO ROTATE AROUND IT. THIS CAUSES MOST STARS IN THE FIELD OF VISION TO APPEAR AS ARCS BUT THOSE CLOSEST TO POLARIS REMAIN IN THE SKY ALL NIGHT AND APPEAR AS A CIRCLE LIKE IN THIS PICTURE. AT THE POLES, ALL STARS WOULD ROTATE IN A CIRCLE.

[Guest]

Thanks for the reply.

I still don't see how all the stars in the picture can blur in every possible direction.
The camera shutter is open for a minute or two and earth rotates in one direction. Everything that moves (or appears to move relative to the camera) will "streak" in the opposite direction, leaving a slight arc.

[The Meal]

HA Rey describes the motion of the stars as such:

Imagine the portion of the sphere of stars is painted inside an umbrella. The stars rotation through the sky as if the umbrella is pointed directly at the North (or south) celestial pole (us North Americans would imagine this huge umbrella is pointed {almost} directly at Polaris). Now spin the umbrella (slowly ) and see how the stars move. Those very close to the poles will just do little circles in the sky. Those closer to the celestial equator will move closer to straight-lines.

Hope this helps!

~Neal

[Guest]

Ah, so the cameraman has Polaris positioned behind the tower, giving the visual effect. I think I get it now. Thanks to both for your replies!

[Solo Owl]

If you were at the Equator, both the north and south celestial poles would lie on the horizon. So you would not see arcs. A time exposure would look something like the inside of a barrel. See (for example) the diagrams on pages 62-63 of Anthony Aveni's book Skywatchers.

[Guest]

And you can determine your latitude from the angle between the point in the sky that the stars appear to revolve around and the horizion.