What causes the polar North Star to change it's position over time?
[From: ] [author: ] [Date: 14-06-18] [Hit: ]
has a proper motion relative to Earth of 0.065 arc seconds per year, so, like all stars, is moving through space. The Earths polar axis is only pointing close to Polaris at present because the polar axis gradually shifts across the sky in a large circle,......
The star which is currently the Pole Star, whose correct name is Polaris, has a proper motion relative to Earth of 0.065 arc seconds per year, so, like all stars, is moving through space. The Earth's polar axis is only pointing close to Polaris at present because the polar axis gradually shifts across the sky in a large circle, something called "precession." All spinning bodies, including children's tops, exhibit precession. Watch a top spin and you will see it.
Source(s):
http://en.wikipedia.org/wiki/Precession
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http://en.wikipedia.org/wiki/Precession
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1) precession
2) Chandler Wobble
3) the proper motion of Polaris
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The earth rotates so some months you see certain stars then about a year later you see the same stars again then in like a few months you see different stars in replace of the first set of stars since earth rotates around the sun like on different parts of the sun earth gets night an sees new stars
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As GeoffG stated > Precession > The axis of the Earth Wobbles.
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The Earth spins about it's axis once per day; That axis also shifts slightly every year; it's precession caused by both the moon and sun, but primarily the moon. Like a gyroscope set on a table top, you can see it's axis shift around in a circle, caused by Earth's gravity. The same thing happens to Earth's axis, in lunar and solar gravity.
In 13,000 years, Vega will be our new "North Star" for a bit.
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