IOAA Jr. 2022, Теория, тест с избираем отговор — Задача 2. The Sun on the Horizon
International Olympiad of Astronomy and Space Sciences for Juniors — Romania– Câmpulung Moldovenesc — October 31 - November 7 2022 — Theoretical Round — I. Multiple choice problems – 100 points · 31 октомври 2022 г.
I. Multiple choice problems – 100 points
For these problems, you have to choose only one correct answer. Please write your answer on answer-sheet. Don’t forget to write the number of the problem, i.e Grid 1. (c).
Условие
The astronomical refraction correction, , has the minimum value, , when the star is at the zenith of the Earth's surface observer , and has the maximum value, , when the star, whose light passes through the Earth's atmosphere, in order to reach the Earth's surface observer, is at the horizon , that is, when the star rises or sets.
It is known, that for an observer, atmospheric refraction raises the Sun in the moments of sunrise and sunset, that is, when it is below the horizon, approximately at its edge, by an apparent disk.
It is given: the radius of the Sun, the distance between the centre of the Earth and the centre of the Sun, .
The value of ,is:
a)
b)
c)
d)
Отговори
- d)
Решение
Atmospheric refraction raises the Sun above its horizon, at its limit, at sunrise and sunset, approximately, with an apparent disk, as shown in the drawing in Figure 1.
Therefore, in reality, the rising of the upper arc of the Sun's disk begins after the moment when we already see the entire solar disk above the horizon. We see the sunrise and sunset, later than they actually occur, which makes the day a little longer.
I mean, I see the disk of the whole Sun above the horizon, at its limit, but the Sun has not yet risen, it is still below the horizon !
I mean, the sun went down, it went down below the horizon, at the edge of it, but I still see the whole disk of it above the horizon !
Under these conditions, the astronomical refraction has the maximum value :
which proves that the value of the maximum astronomical refraction correction, , is approximately equal to the apparent angular diameter of the Sun, .
Оригинал в Архива: Multiple_Choice.pdf · официални решения: Grid_1.pdf · допълнителни данни: Grid_2.pdf · допълнителни данни: Grid_3.pdf · допълнителни данни: Grid_4.pdf · допълнителни данни: Grid_5.pdf · допълнителни данни: Grid_6.pdf · допълнителни данни: Grid_7.pdf · допълнителни данни: Grid_8.pdf · допълнителни данни: Grid_9.pdf · допълнителни данни: Grid_10.pdf