O CAMPO MAGNÉTICO DA TERRA

http://www.youtube.com/watch?v=9SyLGsBBdVE

http://www.youtube.com/watch?v=s0RSYieEa_Q

http://www.youtube.com/watch?v=GzDRBgJtm9E

http://www.youtube.com/watch?v=3HNpAw15t7Y

http://www.youtube.com/watch?v=b-PpUjLZvlY

http://www.youtube.com/watch?v=KDN4Ff-QNCk