... The most spectacular view however is from space, where large areas of aurora can be observed simultaneously, even the entire polar cap. ... Such pictures often show a continuous ring of aurora around the polar cap (picture above), caused mostly by electrons leaking out along magnetic field lines, from the plasma sheet of the Earth's magnetic tail. ... Field lines from the auroral oval are believed to lead to the plasma sheet. ... A near-Earth circular polar orbit has many uses. ...

... The most spectacular view however is from space, where large areas of aurora can be observed simultaneously, even the entire polar cap. ... Such pictures often show a continuous ring of aurora around the polar cap (picture above), caused mostly by electrons leaking out along magnetic field lines, from the plasma sheet of the Earth's magnetic tail. ... Field lines from the auroral oval are believed to lead to the plasma sheet. ... A near-Earth circular polar orbit has many uses. ...

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 . ...

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,