When you take a long exposure photo of the sky at night, the result is many circular trails of light surrounding a central star (Polaris). I still can’t wrap my head around how this seemingly remains a constant with all the different orbital motions (spin, rotation, tilt, wobble) that earth is continously going through.
I know it’s said that Polaris hasn’t *always* been the North Star or center of rotation in the sky, and that it supposedly shifts over many hundreds of years. But, how is it possible to remain constant for *any amoung of time* with us spinning around a wobbling axis at around 1000 MPH, while we rotate around the sun, and the entire solar system is rotating? Shouldn’t that mean there are three different axises of rotation and the center of any star trail photo would be changing daily if not minute-by-minute?
I have also heard that this phenomena remains constant because the stars are just *too far* away (trillions of miles) for the movement to be discernable/ noticable.. which makes even less sense to me. -If you attached a laser pointer to a gently rotating, wobbling object, and aim it at a very close surface, the amount of movent of the beam on the surface might be very minimal/ negligable. But, if you aim it at a very distant surface (trillions of miles away) the amount of movent will be exponentially more significant. The same should be true for a fixed camera lens perspective, especially over the course of hundreds of years.
So I guess what I’m saying is; how does our axis of spin continuously align with Polaris while that axis is also on a wobble, and that wobbling axis of earth is rotating within an also-rotating solar system, AND while everything in the cosmos is constantly expanding?
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The star is too far away to even notice even with all those orbital phenomena happening at the same time.
Instead of using a rotation motion example I will use a linear motion, but the principle is equivalent.
Watch [this video](https://www.youtube.com/watch?v=oHMTEdCEUG4) of a bullet train travelling at high speeds in Japan. Notice how close objects such as the railway walls and houses seem to pass by much faster than the mountains in the horizon. Near objects seem to move at much faster speeds than those far away. Now if there was a moon in the sky it would look as if is wasn’t moving at all.
Now going back to rotational motion.
The same concept applies when the Earth is rotating around its axis. Let’s make an analogy: Imagine an ant resting on the upper half of a spinning disco ball hanging by a thread from a ceiling. If the ant looked at the exact point where the thread is attached to the ceiling it would look as if it is stationary and the rest of the room is spinning around it. If the ant could take a long exposure picture of the room it would be the same as us taking a picture from the sky during night time, the point where the string attaches to the ceiling (Polaris) would look stationary and the rest of the room (the night sky) spins around.
The effects you mentioned don’t really matter because they are are much much slower than the rotation of the Earth. Earth’s rotation = 1 day, Earth’s orbit = 1 year, Earth’s wobble/tilt change = tens of thousands of years.
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