by shiram » Sat May 09, 2015 3:20 pm
Jarod997 wrote:Thank you Chris - that's what I thought. The earth still spins on it's axis, is just where that axis is pointing in space that changes over time. It's like taking a photo of a speeding car with 1/4 second exposure time and being asked to identify the make and model - sort of. (The car is... yellow.
![Wink ;)](./images/smilies/icon_wink.gif)
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I can see how this composite can be misleading, but I still think it was cleaver of the photographer to make the spiral around a different star from Polaris.
As people have commented, I think the composite can be misleading, too. And I commented on SpaceWeather.com site (posted before APOD) and discussed on that point with the contributor by private e-mail.
By the way,
without "including a landscape",
making a spiral around a different star from Polaris to reproduce a startrail in the far past or future has already been done in 1974 by Mr. Yukio Hiramatsu in a single-shot exposure using a film camera.
(
http://www.hamamatsu-space-hunters-club ... _page.html ... This is a Japanese site, and the 5th photo from the top is B.C. 3000 diurnal motion reproduction.)
Detailed system configuration is unknown, but he seemed to use a similar double-guide system, because it requires two independent rotary systems to fix a different star from Polaris and to rotate other stars around the fixed star. Hiramatsu took the photo in 20 minutes and every trail has about 5 degrees, so the second guide's speed seems to be the same as a usual guide. He won the Grand Prize for the Best Idea in a monthly magazine "Ten-mon Guide" (Astronomical Guide) July 1974. And the editor said, "This photo can puzzle the future archaeologists."
Hiramatsu's photo does not contain any landscape, because it was taken by a film camera in a single shot, so it is easier than Miguel's composite with a landscape.
But I feel an anxiety that Miguel's one could mislead people to misunderstand that the future celestial north pole shifts in the sky due to including landscape.
[quote="Jarod997"]Thank you Chris - that's what I thought. The earth still spins on it's axis, is just where that axis is pointing in space that changes over time. It's like taking a photo of a speeding car with 1/4 second exposure time and being asked to identify the make and model - sort of. (The car is... yellow. ;) )
I can see how this composite can be misleading, but I still think it was cleaver of the photographer to make the spiral around a different star from Polaris.[/quote]
As people have commented, I think the composite can be misleading, too. And I commented on SpaceWeather.com site (posted before APOD) and discussed on that point with the contributor by private e-mail.
By the way, [u]without[/u] "including a landscape", [i]making a spiral around a different star from Polaris[/i] to reproduce a startrail in the far past or future has already been done in 1974 by Mr. Yukio Hiramatsu in a single-shot exposure using a film camera.
( http://www.hamamatsu-space-hunters-club.com/hiramatsu_page.html ... This is a Japanese site, and the 5th photo from the top is B.C. 3000 diurnal motion reproduction.)
Detailed system configuration is unknown, but he seemed to use a similar double-guide system, because it requires two independent rotary systems to fix a different star from Polaris and to rotate other stars around the fixed star. Hiramatsu took the photo in 20 minutes and every trail has about 5 degrees, so the second guide's speed seems to be the same as a usual guide. He won the Grand Prize for the Best Idea in a monthly magazine "Ten-mon Guide" (Astronomical Guide) July 1974. And the editor said, "This photo can puzzle the future archaeologists."
Hiramatsu's photo does not contain any landscape, because it was taken by a film camera in a single shot, so it is easier than Miguel's composite with a landscape.
But I feel an anxiety that Miguel's one could mislead people to misunderstand that the future celestial north pole shifts in the sky due to including landscape.