[Richard_B]

Richard_B asked the Naked Scientists:

Hi naked people.
 
I just listened to a podcast in which it mentioned  how clever birds are and how scientists have proposed how birds can see the  earth's magnetic field due to a certain molecule in their eye and use this to  navigate their way across thousands of miles.
 
As the earth's magnetic field follows a north/south  direction, would birds only be able to navigate  using them if they are travelling north or south, e.g. following the 'lines'  that run from north to south?
 
Can birds use the earth's magnetic field if  travelling across the field lines, i.e. east to west. Surely all they would  see would be a series of lines going across their path and disappearing off to  the horizon to their left and right and this would give them no clue as to what  to head for.
 
Great work on the podcasts - amazing how you can  explain the most complex science questions in such easy to understand language.  
 
 Thanks,
 Richard Brown
 Norwich

What do you think?

[LeeE]

Whether birds can 'see' magnetic fields, or whether the magnetic fields affect another organ is, I think, still debatable.  Either way though, they probably rely upon the Dip angle.

http://en.wikipedia.org/wiki/Dip_angle
http://en.wikipedia.org/wiki/Dip_circle