There were http://www.imperial-library.info/content/pocket-guide-empire-third-edition-magic-aetherius, IIRC, and a space colony on one of the moons.
And let's not forget KINMUNE.
Visit to Aetherius occur even less frequently than to Oblivion, for the void is a long expanse and only the stars offer portal for aetherial travel, or the judicious use of magic. The expeditions of the Reman Dynasty and the Sun Birds of Alinor are the most famous attempts in our histories, and it is a cosmic irony that both of them were eventually dissolved for the same reason: the untenable expenditures required to reach magic by magicka. Their only legacy is the Royal Imperial Mananauts of the Elder Council and the great Orrery at Firsthold, whose spheres are made up of genuine celestial mineral gathered by travelers during the Merethic Era.