The Discovery of the Galilean Satellites . ... Probably the most significent contribution that Galileo Galilei made to science was the discovery of the four satellites around Jupiter that are now named in his honor. Galileo first observed the moons of Jupiter on January 7, 1610 through a homemade telescope. He originally thought he saw three stars near Jupiter, strung out in a line through the planet. ... Galileo's Observations of Jupiter's Moons . ... Jupiter . ...

The Earth's own magnetic field is probably created in the Earth's core, believed to contain molten iron, by a "fluid dynamo" . ... During that one hour the Earth rotates by a rather small angle, 15 degrees, and if "open" field lines in the lobes connect it to the solar wind, those lines might become twisted by about 15 degrees. ... Therefore, our average view of the magnetosphere, and most pictures in these files, draw the Earth's magnet as perpendicular to the solar wind. ...

... The planets differ greatly in size and properties, and their fields differ too. ... In 1959, after the Earth's radiation belt had been discovered, Frank Drake observed Jupiter and concluded from the relative intensities in a range of wavelengths that the signal was probably emitted by electrons trapped in a strong magnetic field. Then in 1973 the space probe Pioneer 10 passed by Jupiter and found there, sure enough, an enormous planetary magnetic field and a very intense radiation belt. ...

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,