Unraveling the Relationship Between Magnetic North and Solar East

In summary: The Earth's magnetic field is generated by movement of the iron core, and there's a lot more to that than just the rotation of the surface of the earth. Wikipedia is not always reliable, but in this case the article looks pretty reasonable: http://en.wikipedia.org/wiki/Earth%27s_magnetic_field
  • #1
jjustinn
164
3
This morning I was momentarily struck by the coincidence that magnetic North and "solar East" (the direction of the rising sun) happened to be (approximately) perpendicular, but now it doesn't really seem coincidental; as I understand it, spinning of the Earth causes a current that leads to the magnetic poles, as well as the sunrise.

So, if you woke up on an unknown planet with a compass and you faced magnetic north (assuming one existed), would the sun (or whatever astronomical object/objects) always come up over your right shoulder?
 
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  • #2
The sun does not rise every day at the same point of the horizon. In other words, what you call the 'solar East' lies in the same place only two days in the year.
 
  • #3
NTW said:
The sun does not rise every day at the same point of the horizon. In other words, what you call the 'solar East' lies in the same place only two days in the year.

I intended to cover that with the weasle-word "approximate", along with e.g. the deviation of magnetic from geological "North", finite propagation speed of electromagnetic effects, general-relativistic corrections, &c.
 
  • #4
In our planet, what you call 'the solar East' varies widely with the latitude of the observer and the time of the year. On the equator, where that variation is minimal, tha azimuth of the rising sun may depart +/- 22,5 degrees from due East, and that extreme azimuth grows with the latitude of the observer, reaching a maximum of 90 degrees at the arctic circle, where the sun rises due north in the summer solstice, and due south in the winter solstice.
 
  • #5
Even on earth, It doesn't always work. The magnetic field flips, but the direction of rotation does not.
 
  • #6
Jupiter's magnetic poles are opposite to Earth's yet it spins in the same direction. In fact, the "north" pole of the Earth is actually a "south" magnetic pole, with the "north" magnetic pole at the southern geographic pole. The reason we call the north pole "north" is because the north pole of a magnet (like the needle in a compass) will seek the magnetic pole located there.
 
  • #7
jjustinn said:
as I understand it, spinning of the Earth causes a current that leads to the magnetic poles

The Earth's magnetic field is generated by movement of the iron core, and there's a lot more to that than just the rotation of the surface of the earth. Wikipedia is not always reliable, but in this case the article looks pretty reasonable: http://en.wikipedia.org/wiki/Earth's_magnetic_field
 

1. What is magnetic north?

Magnetic north is the direction that compass needles point towards, which is the direction of the Earth's magnetic field at a particular location.

2. How is magnetic north different from true north?

Magnetic north is different from true north, which is the direction towards the North Pole, because the Earth's magnetic field is not aligned with the geographic north pole.

3. How does the Earth's magnetic field affect navigation?

The Earth's magnetic field is used in navigation to determine direction and orient maps. It is also used by animals like birds and sea turtles to navigate during their migrations.

4. What causes the Earth's magnetic field?

The Earth's magnetic field is generated by the movement of molten iron in its outer core. This creates electric currents that produce the magnetic field.

5. What is the significance of solar east?

Solar east is the direction of the sunrise, which changes throughout the year due to the Earth's tilt on its axis. It is used to determine the time of day and can also be used for navigation in combination with magnetic north.

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