... In the 1800s it was already evident that the Earth's magnetic field was involved: auroral rays seemed to follow the Earth's magnetic field lines, and the frequency with which aurora was observed depended on the distance from the magnetic pole, not from the geographic one. ... That is the beginning of the ionosphere , a layer with enough free electrons (and ions) to play an important role in radio communications. ... The simplest atom is the one of hydrogen, with just one electron. ...

... Field Lines . ... Charged particles--ions and electrons--can be trapped by the Earth's magnetic field. ... A fast rotation (or "gyration") around magnetic field lines, typically thousands of times each second. ... A slow drift around the magnetic axis of the Earth, from the current field line to its neighbor, staying roughly at the same distance from the exis. ... Electrons and ions, of the energies commonly encountered in the magnetosphere, tend to circle around magnetic field lines. ...

Hubble Finds Oxygen Atmosphere On Jupiter's Moon Europa . Astronomers using NASA's Hubble Space Telescope (HST) have identified the presence of an extremely tenuous atmosphere of molecular oxygen around Jupiter's second moon, Europa . ... Europa's oxygen atmosphere is so tenuous that its surface pressure is barely one hundred billionth that of the Earth," said Principal Investigator Doyle Hall, of Johns Hopkins. ... The oxygen gas slowly leaks into space and must be replenished continuously. ...

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,