.

William Gilbert . The north-south pointing property of the compass needle was discovered in China around the year 1000, and in 1600 William Gilbert in London showed that this could be explained by the entire Earth being a huge magnet. As a model for the magnetic Earth he used a spherical magnet, which he called "terrella" , the "little Earth." He moved a small compass over the surface of the terrella and demonstrated that it always pointed towards its magnetic poles. ... Magnetic Fields . ...

... Jupiter's icy moon Europa has a metallic core and layered internal structure similar to the Earth's , while the heavily cratered moon Callisto is a mixture of metallic rock and ice with no identifiable central core, according to new results from NASA's Galileo mission . In addition, recent plasma wave observations from Galileo show no evidence of a magnetic field or magnetosphere around Callisto, but do hint at the prospect of a tenuous atmosphere. ... Jupiter Galileo . ...

Cosmic Research, Vol. 42, No. 5, 2004, pp. 435­488. Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 5, 2004, pp. 453­508. Original Russian Text Copyright © 2004 by Veselovsky, Panasyuk, Avdyushin, Bazilevskaya, Belov, Bogachev, Bogod, Bogomolov, Bothmer, Boyarchuk, Vashenyuk, Vlasov, Gnezdilov, Gorgutsa, Grechnev, Denisov, Dmitriev, Dryer, Yermolaev, Eroshenko, Zherebtsov, Zhitnik, Zhukov, Zastenker, Zelenyi, Zeldovich, Ivanov-Kholodnyi, Ignat'ev, Ishkov, Kolomiytsev, Krasheninnikov, Kudela,