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Calcular la altura con la que se verá el Sol desde la situación: l=22°57,0´N; L=160°36,0´W, el 30 de marzo de 2022 a las 18:00 UT. (EN EL EXAMEN SE LES FACILITARON DOS DATOS QUE FALTABAN: HORARIO 88º54,2' Y DECLINACIÓN +3º 57,9')Calculate the Sun's altitude from position l = 22° 57.0' N, L = 160° 36.0' W on 30 March 2022 at 18:00 UT (given GHA = 88º 54.2' and declination = +3º 57.9').
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Correct answer: b) 18° 23.3'.
Why it is correct
Being west, P = L − GHA = 160º 36.0′ − 88º 54.2′ = 71º 41.8′ E. Applying sin a = sin(22º 57′) sin(3º 57.9′) + cos(22º 57′) cos(3º 57.9′) cos(71º 41.8′) = 0.31545 gives a = 18º 23.3′.
Why the others are not
- a) That is the zenith distance (90º − 18º 23.3′ = 71º 36.7′), not the altitude.
- c) Subtracts the sine product when both latitude and declination are north.
- d) That is the complement of 21º 24.1′.
How to work it out in the exam
- Do not confuse altitude (arcsin) with zenith distance (arccos).
Where this question comes from
- Ministerio de Transportes (Madrid) · 2022 · Convocatoria de diciembre · CY Test 1 · question 12 Official paper · Official answer key
- Ministerio de Transportes (Madrid) · 2022 · Convocatoria de diciembre · CY Test 2 · question 19 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.