[Yeade]

Thanks for all the information, Nerwen, Galadriel55, and Legate of Amon Lanc! I really appreciate the help!

Though the Elves clearly journeyed across the other known lands of Middle-earth in addition to Beleriand on their way from Cuiviénen to Aman, I'm afraid that's just not going to be possible in my sci-fi adaptation. I've got my heart set on the Valar being the source of the general technological upgrade, which in turn means nobody can take off as interplanetary explorers until the Noldor return in pursuit of Melkor and their scientific knowledge has a chance to disseminate.

So, Anor and Isil are binary stars separated by, say, a mean distance of 200-500 AU (astronomical unit), with Beleriand and later Númenor in orbit around the latter. Elves, Men, and Dwarves can travel between the two planetary systems throughout the First Age, perhaps to escape the ravages of Morgoth, and for most of the Second Age before the Downfall of Númenor renders hyperspace inaccessible except for the Straight Road. I rather like that this gives the Elves and Númenórean exiles an additional reason to honor Isil in their iconography. Isil, while still visible as the brightest star in the night sky, and the worlds of their origins are forever lost to them by the Third Age.

A couple more questions:

The mearas or their ancestors are supposedly brought to Middle-earth by Oromë, right? I've brainstormed some preliminary ideas for the Rohirrim already and need to work out how their most famed horses fit in. Another alien species?

Are there any canon descriptions of the Havens of Umbar? The harbor must be deep and wide enough to stage a fleet of warships, and there are presumably extensive quays, upon which Aragorn as Thorongil fights the Corsair captain. A poster over on LJ mentioned that there's a white pillar with a shining crystal globe set at the top--a sort of lighthouse, I guess? I admit I've never heard of any such thing. Is this maybe referenced in The Silmarillion ("Akallabêth"?), HOME, or elsewhere, like Tolkien's letters?