Alaalu
The single inhabited planet of a star located almost directly across the Milky Way galaxy from us in "Outer Arm Four", a sub-arm of the intragalactic Scutum Arm, "around Radian one-sixty" in the Galactic coordinate system used by wizards, and about sixty thousand lightyears away. The system primary, a small G0-type star, is about the same size as Earth's Sun. However, the star is hidden from Earth's view by the clouds of interstellar / intragalactic gas and dust between the Solar System and the Galactic core, so it has no name in Terran astronomical taxonomy. If it could be seen, it would be somewhere in the constellation Sagittarius.
Alaalu is the fourth planet out from its primary. It is a fairly large world, some thirty-six thousand miles in diameter, with almost ninety percent of its surface covered by water. The planet's orbit is close enough to its sun, and its axial tilt is shallow enough, to make for an extremely mild and pleasant climate for carbon/water-based life. There are only three main landmasses -- one crescent-shaped mass which may be the remnant of some very ancient meteoric impact, and two long island chains. The planet is low-density and relatively metal-poor, as is often the case with such large Earth-type worlds. The indigenous humanoid species is a tall, slender, brownskinned people.
Nita and Kit are sent to stay with a typical Alaalid family during their "student exchange" excursus in WH. At that time the Alaalid population is estimated to be about one billion -- and Nita and Kit are surprised to discover that a planet with such a population has only one wizard. (WH)