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I love Polaris, but there is something that still escapes me


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Hello everybody, thanks for accepting me in the forum. 
I came here because I would like to be able with your help to clear for myself a huge doubt that I have been carrying around since high school, a question that actually remained buried in the depths of my mind for years, only to resurface this summer after I spent hours and hours observing the night sky trying to cool down a bit.

Polaris is about 75 arc/sec away from the north celestial pole, so it is 3/4 of a degree away from the Earth's rotation axis. To understand how wide the equivalent sky angle is, I personally take the average width of the lunar disk as a reference, which as you know is about half a degree. While staring at Ursa Minor this summer I focused on Polaris and obviously I could not notice any circular movement around the axis, so I went to YT to watch some "star trailing" videos and even there Polaris remains practically fixed. However, I found one video with a more powerful zoom in which you can see that Polaris actually seems to hint at a very small drawn circle. The question remains the same though, the circle Polaris seems to draw is still much smaller than the one that the distance of Polaris from the celestial North Pole would suggest. 
Someone could please explain which element I am completely ignoring and what factor I am not taking into consideration regarding the alleged discrepancy between the fact that Polaris, in its nocturnal movement, should make a circle around the the Earth's axis whose radius is the equivalent of one and a half times the apparent width of the Moon in the sky, while instead with the naked eye we do not see any of this and we also struggle to detect it with time lapses? Something certainly escapes me. 

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I miswrote 75 arc/sec and I can't edit it out. What I mean is that the distance of Polaris from the celestial north pole is about 0.7 degrees, while the width of the lunar disc has an average size of 0.5 degrees

Edited by Oibaf77
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Hi and welcome to the forum. I have not got a clue about the answer and do not worry about it at all. I see you have asked the same question on astronomia.com too.

@Oibaf77, a presentation in the specially dedicated introduce yourself section is welcome so that people know what you are interested in so they can phrase a suitable reply 🙂

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1 hour ago, TerryMcK said:

Hi and welcome to the forum. I have not got a clue about the answer and do not worry about it at all. I see you have asked the same question on astronomia.com too.

@Oibaf77, a presentation in the specially dedicated introduce yourself section is welcome so that people know what you are interested in so they can phrase a suitable reply 🙂

 

Hi, yes I have asked the same question on an Italian dedicated forum and I also posted it here to reach a wider audience that could help me. You got me. Can I ask you how you can see it? Do you see it from my profile here? 

Ok, you dont care about my question at all, message received. Was not this place supposed to  be friendly and easy? That's why I clicked it when I googled astronomy forums. I didn't introduce myself in the dedicated section because I thought it was pretty much the same to explain directly in the post what I am interested in and why I came here, like I did. 

Edited by Oibaf77
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Yes we are friendly however I myself do not know the answer to your question not that I do not care about your question. I am also on the Italian forum too and it came up in my feed at almost the same time.

Normally most people introduce themselves but it is not mandatory.  Hope this explains it.

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  • 4 weeks later...
On 8/18/2022 at 5:29 PM, Oibaf77 said:

Hello everybody, thanks for accepting me in the forum. 
I came here because I would like to be able with your help to clear for myself a huge doubt that I have been carrying around since high school, a question that actually remained buried in the depths of my mind for years, only to resurface this summer after I spent hours and hours observing the night sky trying to cool down a bit.

Polaris is about 75 arc/sec away from the north celestial pole, so it is 3/4 of a degree away from the Earth's rotation axis. To understand how wide the equivalent sky angle is, I personally take the average width of the lunar disk as a reference, which as you know is about half a degree. While staring at Ursa Minor this summer I focused on Polaris and obviously I could not notice any circular movement around the axis, so I went to YT to watch some "star trailing" videos and even there Polaris remains practically fixed. However, I found one video with a more powerful zoom in which you can see that Polaris actually seems to hint at a very small drawn circle. The question remains the same though, the circle Polaris seems to draw is still much smaller than the one that the distance of Polaris from the celestial North Pole would suggest. 
Someone could please explain which element I am completely ignoring and what factor I am not taking into consideration regarding the alleged discrepancy between the fact that Polaris, in its nocturnal movement, should make a circle around the the Earth's axis whose radius is the equivalent of one and a half times the apparent width of the Moon in the sky, while instead with the naked eye we do not see any of this and we also struggle to detect it with time lapses? Something certainly escapes me. 

 

Hi,

 

Checking on Skysafari shows exactly the kind of behaviour which you are expecting. Perhaps the videos you checked were still fairly low magnification? Half a degree of sky is still surprisingly small.

 

Hopefully one of these will work, they show the NCP with Polaris moving around it at hourly intervals for 24 hours. The red rings are TelRad circles so the inner one is 0.5 degrees, outer one is 2 degrees.

 

Hope that is of some help.

3984122C-8466-4AA3-91DD-C347837F0E7E.gif

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