Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

If I had a magnetic bar in space that was 2cm wide and 2cm high and was one Earth diameter long and had the same magnetic strength as the Earth, would the distribution of field lines be the same length and width as the Earth's field lines?

share|cite|improve this question
Your bar will not work as you want. It will break apart. Too long and too thin. So no shielding. – Asphir Dom Mar 8 '13 at 10:25

The magnetic field of the earth looks approximately like the field of a magnetic dipole with field values on the order of tens of micro Tesla. The magnetic field of a bar magnet also is essentially that of a magnetic dipole, so provided the bar magnetic creates a field that is also on the order of tens of micro Tesla, the field lines would look similar in length at given distances from the poles (not sure I understand what you mean by the width of field lines). There's a great image on the Wikipedia page for the magnetic field of the earth in which you can clearly see that the field looks very much like that of a magnetic dipole, especially away from its surface. One difference, however, is that since the magnetic field of the Earth is produced by molten iron whose motion is constantly changing its magnetic field, the magnetic field of a bar magnet is fixed.

share|cite|improve this answer
Now that I have yes answer my other questions are would it deflect solar radiation the same as the Earth? – Jitter Feb 6 '13 at 9:27
Could we change it to a strong magnet to deflect more solar radiation. Could we scale it down for a spacecraft. – Jitter Feb 6 '13 at 9:31
I'm not sure if I should make new questions or discuss it here? – Jitter Feb 6 '13 at 9:39
Would a magnetic rod through Mars shield it from solar radiation? – Jitter Feb 6 '13 at 9:40
Yes, as you noted, there is a component of the geomagnetic observed that is not described by the single dipole model (as much as 20% in some places.) This is due to the interaction of solar particles and ionosphere, rock-magnetism of the earth's crust, and the non-dipole components of the field generated in the outer core. – Mark Rovetta Mar 8 '13 at 19:57

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.