English

Noun

sphaera recta ‎(singulare tantum)

1. (astronomy) An idealised conception of the celestial sphere in which the celestial equator is perpendicular to the local horizon and the Sun reaches the zenith at its highest point.
   • 1932, Sir Thomas Little Heath, Greek Astronomy, page 135

     There is a certain region lying to the south of us which is said to be under the equator, where the poles fall on the horizon, and the sphere of the universe stands straight up, as it were (sphaera recta).

   • For more examples of usage of this term, see Citations:sphaera recta.

Antonyms

• sphaera obliqua