Hover or tap underlined Spanish terms to see their translation and exam tip.
¿Qué diferencia hay entre el ángulo sidéreo y el ángulo horario de una estrella?What is the difference between the sidereal hour angle and the local hour angle of a star?
Show the answer
Correct answer: d) Sidereal hour angle is measured from the First Point of Aries and local hour angle from the observer’s upper meridian.
Why it is correct
Both Sidereal Hour Angle (SHA / AS) and Local Hour Angle (LHA / HL) are measured westward along the celestial equator from 0° to 360°, but from different origins: SHA is measured from the First Point of Aries (♈), whereas LHA is measured from the observer’s upper meridian.
Why the others are not
- a) They have different origins: Aries for SHA and the observer’s meridian for LHA.
- b) Both are measured westward.
- c) The coordinate measured eastward from Aries is Right Ascension, not Sidereal Hour Angle.
How to work it out in the exam
- SHA vs LHA: both measured westward, but SHA from Aries and LHA from the observer’s upper meridian.
Where this question comes from
- Junta de Andalucía · 2023 · 1ª convocatoria · CY Módulo de navegación · question 3 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.