Does Moon have North and South Poles ?

[call_naveen]

Thanks
Naveen

 

[mgb_phys]

Yes geographically.
The bit at the top is always at the top when viewed from Earth and the bit at the bottom is alwyas at the bottom.
It doesn't have a magnetic field (ok a very tiny one) so doesn't have magnetic poles like the Earth.

 

[Jonathan Scott]

Thanks
Naveen

Yes. Poles of other bodies are defined by their axis of rotation.

The International Astronomical Union (IAU) definition of the North pole for astronomical bodies is the end of the axis of rotation that points in the same direction as the Earth's north pole relative to the plane of the Earth's orbit.

However, others argue that the North pole would be better defined as the one where the rotation appears anticlockwise when looking down on the object, and that definition could also be used for objects in isolation without reference to the solar system, including objects outside the solar system.

The majority of planets and other bodies in the solar system rotate in the same direction, so there are not many bodies for which the two definitions differ.

 

[mgb_phys]

Uranus for instance is tilted by 90deg so it's rotation axis points in the plane of the orbit.
So the 'top' of the planet is a point on the equator and is constantly changing - like the 'side' of the earth. Not sure what you would call the poles of Uranus.

 

[Janus]

Yes geographically.
The bit at the top is always at the top when viewed from Earth and the bit at the bottom is alwyas at the bottom.

Well, not exactly. The Moon has a 6.5° axial tilt with respect to its orbit. So it nods back and forth as seen from Earth so that sometimes the North pole is tilted slightly towards us and sometimes the South pole. This is known as the libration of latitude.

 

[D H]

The International Astronomical Union (IAU) definition of the North pole for astronomical bodies is the end of the axis of rotation that points in the same direction as the Earth's north pole relative to the plane of the Earth's orbit.

Close. The definition is "The north pole is that pole of rotation that lies on the north side of the invariable plane of the solar system."

Seidelmann, P.K. et al (2005), "Report Of The IAU/IAG Working Group On Cartographic Coordinates And Rotational Elements: 2003," Celestial Mechanics and Dynamical Astronomy, 91, pp. 203-215.
Preprint is at http://astrogeology.usgs.gov/Projects/WGCCRE/WGCCRE2003preprint.pdf.