Hover or tap underlined Spanish terms to see their translation and exam tip.
El círculo máximo perpendicular al eje cenit-nadir, cuyo centro coincide con el centro de la Tierra y divide la esfera celeste en los hemisferios visible e invisible, se denomina:The great circle perpendicular to the zenith–nadir axis whose centre coincides with the centre of the Earth, dividing the celestial sphere into visible and invisible hemispheres, is called the:
Show the answer
Correct answer: d) True, Astronomical or Geocentric Horizon.
Why it is correct
The plane perpendicular to the observer’s vertical (zenith–nadir axis) passing through the centre of the Earth intersects the celestial sphere in a great circle called the true, rational, astronomical or geocentric horizon, dividing the sphere into visible and invisible hemispheres.
Why the others are not
- a) 'Geoidal horizon' is not the astronomical term for this great circle.
- b) The visible sea horizon is the small circle where lines of sight from the eye touch the sea.
- c) The sensible horizon is the plane parallel to the true horizon passing through the observer’s eye.
How to work it out in the exam
- True (astronomical/geocentric) horizon: great circle perpendicular to the zenith–nadir axis through Earth’s centre.
Where this question comes from
- Región de Murcia · 2026 · 2ª convocatoria · CY Tipo 1 · question 4 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.