# Rotation direction of Pulsars

Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. It has a very strong magnetic fields which funnel jets of particles out along the two magnetic poles.

• My question is how Pulsars rotate, clockwise or Anti-clockwise?
• Clockwise or anticlockwise rotation depends on (and in some cases, defines) which of the two rotational poles you're looking down at. Apr 25 at 18:50
• Only 2D has the concept of clockwise and anticlockwise. In 3D, the rotation direction is a vector (or more accurately, a pseudovector) that can point in any direction. It gets even more interesting in 4D. Apr 26 at 16:05
• And are pulsars the right way up, or upside-down? This is surely more important! Apr 27 at 16:14
• 'water molecule' states that the axis of rotation 'can point in any direction'. but does it? or is there a correlation? Apr 28 at 23:40

## 1 Answer

Does the Earth rotate clockwise or anticlockwise?

If you are floating above the north pole of Earth you would see the Earth rotating anticlockwise(*) if you were floating above the south pole, you would see the Earth rotating clockwise.

image from ASTRONOMÍA ASTRÓNOMOS UNIVERSO

So the direction of rotation depends on the point of view. You're going to find that many of the truths we cling to depend greatly on our own point of view...

You could say "I'll take the North Pole view". Now how do we define "North Pole" on a pulsar (which is many many times smoother than a billiard ball). One way to define "North Pole" is "the pole from which a an object appears to rotate anticlockwise". Can you see how the definition is going round in circles?

Or you can define "North Pole" in terms of magnetic field. The North pole of the Earth has a magnetic pole (that attracts the North-seeking pole of a compass) You can try to define the "North Pole" of a pulsar in terms of that which has the magnetic pole which corresponds to the that near the North pole of Earth.

The rotation of a pulsar is unrelated to its magnetic field. 50% of pulsars rotate clockwise about their North magnetic pole, and 50% rotate anticlockwise. The rotational direction of a pulsar is derived from the angular momentum of the star from which it is derived. The magnetic field is also inherited from the star. But a star can swap its magnetic field without changing its rotational direction.

There is no preferred direction of rotation, so a pulsar is equally likely to rotate clockwise as anticlockwise.

(*) and so the shadow of the gnomon of a sundial rotates clockwise, and clocks which were made by northern hemisphere horologists follow the convention. If the technological revolution had occurred in Patagonia not Europe, clocks might be very different.

• Do neutron stars or Pulsars rotate around something? As our earth rotates (around the Sun) as well as Spin (around it's axis), so how do neutron Stars behave in this regard? Apr 25 at 19:50
• In general, no, pulsars do not orbit other objects in the way that the Earth orbits the sun. There are binary pulsars, and there are pulsars that are in systems with regular stars or even with black holes. Apr 25 at 20:48
• +1 for "Can you see how the definition is going round in circles?" .... Apr 26 at 10:28
• @Autodidact The terms are that our earth revolves around the Sun while it rotates around its axis and while the Sun revolves around the galactic center. Nearly all celestial bodies rotate to some degree or other. Neutron stars revolve around their parent galaxy's center, and if part of a binary or globular cluster or something, they may revolve around that as well. Apr 26 at 14:56
• @AdamBarnes: Normally you'd want to use an inertial reference frame, not a rotating reference frame. Things are weird (or at least more complicated) in a rotating reference frame, for example centrifugal force is a real force that you have to include in calculations to make Newton's laws of motion work. So taking one celestial body's (or the earth's) rotation as your frame of reference would be a rather poor choice. (Unlike the classic falling-in-an-elevator thought experiment, you can tell the difference between rotating or not, even with eyes closed. Extend your arms, feel the force.) Apr 27 at 11:20