North and south celestial poles

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In summary, the Earth's angular momentum is directed towards the north celestial pole due to its counterclockwise rotation and adherence to the Right Hand Rule. The direction of the angular momentum is determined by the vector cross product in its definition.
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Homework Statement



The Earth's angular momentum is directed toward which celestial pole(north or south)?

Homework Equations



none

The Attempt at a Solution



I just assume that it is the south celestial pole considering that the Earth is spinning from left to right, or west to east.

Is this correct?
 
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  • #2
What is the relationship between the direction of the angular momentum of a body and its actual rotation direction? Is there a rule that governs it?

EDIT: Also, can you see that "left to right" is not very meaningful?
 
  • #3
hmmmm...i can't find the rule but the example in my book shows a bowling ball spinning from what we will call west to east and the angular momentum is directed upward, and if it was spinning opposite this it would be spinning downward. From this i could say that the answer would be the north celestial pole. Also, i was saying left to right when looking at the Earth where the equator has a plane that extends from left to right. But what rule are you referring to?
 
  • #4
I was referring to the Right Hand Rule. Do you know what the definition of angular momentum is? Do you know what a vector cross product is? It's part of that definition, and follows the Right Hand Rule.

EDIT: You have the right answer, but I'm saying all of this to make sure that you understand why. The Earth rotates counterclockwise as viewed from above the North Pole. The Right Hand Rule says that if you curl the fingers of your right hand in the direction of rotation, the thumb points in the direction of the angular momentum (in this case). Mathematically, the reason why ang. mom. follows the Right Hand Rule is because it has a vector cross product in its definition. You should look that up if you do not know what it is.

Also, i was saying left to right when looking at the Earth where the equator has a plane that extends from left to right.

That still doesn't make sense. We're talking about rotation here. Even if you specify how you are oriented, the best you could do would be to specify clockwise or counterclockwise.
 
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  • #5
thanks, i do know what both of those rules are, he just didnt explain it in class yet, guess I was supposed to have picked that up in my book in a chapter we haven't done yet.
 
  • #6
Of course, the cross product's association of "clockwise" with "down" is entirely arbitrary; it isn't any more justified in terms of physics or mathematics than associating clockwise with "up". An alien might as well say Earth's angular momentum is directed towards its north pole.
 

FAQ: North and south celestial poles

What is the difference between the North and South Celestial Poles?

The North and South Celestial Poles are the points in the sky directly above the Earth's North and South Poles, respectively. They are the imaginary points where the Earth's axis would intersect with the celestial sphere, which is an imaginary sphere surrounding the Earth.

How are the North and South Celestial Poles used in navigation?

The North and South Celestial Poles are used as reference points for navigation because they appear to stay fixed in the sky while the stars and other celestial bodies appear to move around them. This makes them useful for determining direction and locating specific stars and constellations.

Are the North and South Celestial Poles visible from all parts of the Earth?

No, the North and South Celestial Poles are only visible from certain latitudes on Earth. The North Celestial Pole is only visible from the Northern Hemisphere, while the South Celestial Pole is only visible from the Southern Hemisphere. The closer you are to the equator, the lower in the sky the Celestial Poles will appear.

What is the significance of the North and South Celestial Poles in astronomy?

The North and South Celestial Poles play a crucial role in celestial navigation and timekeeping. They are used to determine the Earth's rotation and to track the movements of celestial bodies. They are also important for understanding the Earth's tilt and its effect on seasons.

Can the North and South Celestial Poles change over time?

Yes, the North and South Celestial Poles can change position over long periods of time due to the Earth's precession, which is the slow change in the orientation of the Earth's axis. This means that the North and South Celestial Poles may not always point to the same stars or constellations that they do now.

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