... Le t?lescope" Hubble ", en orbite. ... la lumi?re visible, mais absorbe la plupart "des radiations ?lectromagn?tiques", pourtant de m?me famille que la lumi?re: une partie des infrarouges (IR), tous les ultra-violet (UV), les rayons X et gamma. ... Le t?lescope " Hubble ", ( Hubble telescope ) en orbite basse autour de la terre, surmonte ces limites dans la gamme du visible et en partie dans l'UV. ... distance par les astronomes depuis la terre, comme un observatoire bas? au sol. ...

Different types of satellite orbits have different uses: while the synchronous orbit is best for communication satellites, Lagrangian point orbits help monitor the solar wind before it reaches Earth. A low altitude polar orbit is widely used for monitoring the Earth because each day, as the Earth rotates below it, the entire surface is covered. ... A different choice was made for MAGSAT, orbited 1979-80 to survey the Earth's own magnetic field near its surface. ...

Helene . Saturn XII - 1980S6 . Helene was discovered by P. Laques and J. Lecacheus in 1980 through ground based observations. Helene is called a Dione Trojan satellite because it shares the same orbit as Dione at about 60 degrees ahead of its larger companion. ... 1980 . ... Mean density (gm/cm^3) . Mean distance from Saturn (km) . ... Rotational period (days) . Orbital period (days) . ... Mean orbital velocity (km/sec) . ... Credit: Calvin J. Hamilton) . Saturn Dione Rhea . ...

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,