Starship Asterisk*

[quote=Ann post_id=290784 time=1553281743 user_id=129702]
[quote=IIIIIKK post_id=290772 time=1553272126]
Hi,

I'm not sure that the bright centered star is Polaris because in relation to Big Dipper, it must be slightly above (except if it is caused by the distorsion of the lens or due to the projection).
[/quote]

Read the post above yours. :wink:

(But you're right - in reality, the pointers of the Big Dipper would point pretty much straight at Polaris, which they don't do in this picture.)

Ann
[/quote]
The image is most closely replicated by a form of cylindrical projection (sphere projected to a cylinder) which leads to distortions worsening toward the poles; not as severe as a Mercator projection but worse than more familiar images. From Stellarium, the images below show two projection algorithms, cylindrical and stereographic (sphere projected to plane) of [u]identical fields of view[/u]. The latter (right image) is the same as or very close to typical camera images. The views are of the same APOD sky region, and from location close to the photographer. Also visible is the equatorial grid to show the continuity of distortions for both projections. The cylindrical projection (left) fits pretty well to the APOD. The stereographic projection looks more familiar. The pointer stars look more like pointer stars.
 

[float=left][attachment=0]Cylindrical.JPG[/attachment][/float]
[float=right][attachment=1]Stereographic.JPG[/attachment][/float]

[quote=IIIIIKK post_id=290772 time=1553272126]
Hi,

I'm not sure that the bright centered star is Polaris because in relation to Big Dipper, it must be slightly above (except if it is caused by the distorsion of the lens or due to the projection).
[/quote]

Read the post above yours. :wink:

(But you're right - in reality, the pointers of the Big Dipper would point pretty much straight at Polaris, which they don't do in this picture.)

Ann

Hi,

I'm not sure that the bright centered star is Polaris because in relation to Big Dipper, it must be slightly above (except if it is caused by the distorsion of the lens or due to the projection).

[quote=David_from_Slough_UK post_id=290765 time=1553259460]

Great photo, but I'm puzzled. Why do the 'pointers' in the Big Dipper' not point towards the Pole star? Is it some kind of strange distortion with the wide-angle lens?[/quote]
Yes.

Great wallpaper shot! :D 8-)

Great photo, but I'm puzzled. Why do the 'pointers' in the Big Dipper' not point towards the Pole star? Is it some kind of strange distortion with the wide-angle lens?

An amazing image with so much going on...

:---[===] *

[url=https://apod.nasa.gov/apod/ap190322.html] [img]https://apod.nasa.gov/apod/calendar/S_190322.jpg[/img] [size=150]A Symphony in Northern Winter Skies[/size][/url]

[b] Explanation: [/b] Despite the cold, [url=https://apod.nasa.gov/apod/ap181006.html]a chance to view[/url] the shimmering northern lights coaxed this skygazer onto the frozen surface of Lake Superior on the west coast of the Keweenaw Peninusla and offered this nocturnal crescendo as a reward. A northern late winter night sky also plays across the [url=https://www.instagram.com/p/BvE9jH3FlCM/]panoramic composition[/url] of images made between 10pm and 1am on the night of February 28/March 1. At left, a faint band of Zodiacal light rises sharply from the horizon crossing Mars and the Pleides star cluster. Both the distant galaxy M31 and our own Milky Way shine above the greenish [url=https://www.nasa.gov/mission_pages/sunearth/aurora-news-stories/index.html]auroral arc[/url]. Navigational [url=https://apod.nasa.gov/apod/ap190118.html]north pole star[/url] Polaris is centered above and accompanied on the right by the northern night's most recognizable asterism, [url=https://apod.nasa.gov/apod/ap170407.html]the Big Dipper[/url]. Terrestrial lights include markers for two breakwaters on the the horizon near the center of the scene.


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