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In Stellarium when I zoom in on Neptune to be able to see your daily rotation. I select Neptune, center it (space bar) and then make increments of one solar hour (command +). I notice that the axis of rotation seems to wobble (just focus on the big dark spot to notice that), but the precession period of Neptune's axis of rotation is hundreds of years, not hours. How is this possible?. I think it may be due to the combination of the daily rotational movement of us (the Earth) and Neptune, but I cannot get a clear geometric representation of this. Does anyone know why this phenomenon happens?

Thank you.

I have: Stellarium 0.20.4 for Mac OS.

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    $\begingroup$ btw if you don't get an answer then you can also ask this question here, where the developers of stellarium are regulars and will read and reply to you $\endgroup$
    – Aaron F
    May 26 at 21:09
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This appears to me as just the consequence of having an altazimuthally mounted “camera” (the simulation). Objects are tilted towards the left when they rise, towards the right when they. set. You can verify that easily by looking at the Moon when it rises and sets from your own place. This is due to the horizon being “tilted” with respect to the Earth’s plane of rotation (unless you are exactly at the pole).

I’m not super familiar with Stellarium, but as far as I know, there’s a way for the observer to not be located on the Earth, or at least, you can change the latitude of the simulation. Try that, and if you set yourself as being at the Earth’s (north or south) pole, you shouldn’t see that anymore.

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    $\begingroup$ The Stellarium toolbar has a button with a telescope mount icon and tooltip "Switch between equatorial and azimuthal mount [Ctrl+M]." Equatorial mode eliminates the rotation. $\endgroup$
    – Mike G
    May 27 at 2:33

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