IAO 2012, Теория, младша възраст — Задача 5. Venus and Earth
XVII International Astronomy Olympiad — Theoretical round — Group α
Бележка
General note. Maybe not all problems have correct questions. Some questions (maybe the main question of the problem, maybe one of the subquestions) may make no real sense. In this case you have to write in your answer (in English or Russian): «impossible situation – ситуация невозможна». Of course, this answer has to be explained numerically or logically.
Data from the tables (Planetary data, stars, constants, etc.) may be used for solving every problem.
The answers «Да-Yes» or «Нет-No» have to be written in English or Russian.
Planetary data
Элементы орбит. Физические характеристики некоторых планет, Луны, Солнца и Эриды
Parameters of orbits. Physical characteristics of some planets, Moon, Sun and Eris
| Небесное тело, планета / Body, planet | Среднее расстояние от центрального тела / Average distance to central body, in astr. units | in km | Сидерический (или аналогичный) период обращения / Sidereal period (or analogous), in tropical years | in days | Наклон орбиты / Orbital inclination, | Эксцентриситет / Eccentricity, | Экваториальн. диаметр / Equat. diameter, km | Масса / Mass, kg | Средняя плотность / Av. density, g/cm³ | Ускор. своб. пад. у пов. / Grav. accelr. at surf., m/s² | Наклон оси / Axial tilt | Макс. блеск, вид. с Земли / Max. magn. From Earth **) | Альбедо / Albedo |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Солнце / Sun | 1392000 | 1989000 | 1,409 | ||||||||||
| Меркурий / Mercury | 0,387 | 57,9 | 0,241 | 87,969 | 0,206 | 4 879 | 0,3302 | 5,43 | 3,70 | 0,06 | |||
| Венера / Venus | 0,723 | 108,2 | 0,615 | 224,7007 | 3,40 | 0,007 | 12 104 | 4,8690 | 5,24 | 8,87 | 177,36 | 0,78 | |
| Земля / Earth | 1,000 | 149,6 | 1,000 | 365,2564 | 0,00 | 0,017 | 12 756 | 5,9742 | 5,515 | 9,81 | 23,44 | 0,36 | |
| Луна / Moon | 0,00257 | 0,38440 | 0,0748 | 27,3217 | 5,15 | 0,055 | 3 475 | 0,0735 | 3,34 | 1,62 | 6,7 | 0,07 | |
| Марс / Mars | 1,524 | 227,9 | 1,880 | 686,98 | 1,85 | 0,093 | 6 794 | 0,6419 | 3,94 | 3,71 | 25,19 | 0,15 | |
| Юпитер / Jupiter | 5,204 | 778,6 | 11,862 | 4 332,59 | 1,30 | 0,048 | 142 984 | 1899,8 | 1,33 | 24,86 | 3,13 | 0,66 | |
| Сатурн / Saturn | 9,584 | 1433,7 | 29,458 | 10 759,20 | 2,48 | 0,054 | 120 536 | 568,50 | 0,70 | 10,41 | 26,73 | 0,68 | |
| Эрида / Eris | 68,05 | 205 029 | 43,82 | 0,435 | 2 326 | 0,0167 | 2,52 | 0,7 | 0,96 |
**) Для Луны – в среднем противостоянии.
**) For Moon – in mean opposition.
Константи
Некоторые константы и формулы / Some constants and formulae
| Скорость света в вакууме, c (м/с) | 299 792 458 | Speed of light in vacuum, c (m/s) |
| Гравитационная постоянная, G (Н·м²/кг²) | Constant of gravitation, G (N·m²/kg²) | |
| Солнечная постоянная, A (Вт/м²) | 1367 | Solar constant, A (W/m²) |
| Параметр Хаббла, (км/с/МПк), среднее значение | 71 | mean value, Hubble parameter, (km/s/Mpc) |
| диапазон значений | 50-100 | diapason of values |
| Постоянная Планка, h (Дж·с) | Plank constant, h (J·s) | |
| Заряд электрона, e (Кл) | Charge of electron, e (C) | |
| Масса электрона, (кг) | Mass of electron, (kg) | |
| Соотношение масс протона и электрона | 1836.15 | Proton-to-electron ratio |
| Постоянная Фарадея, F (Кл/моль) | 96 485 | Faraday constant, F (C/mol) |
| Магнитная постоянная, (Гн/м) | Magnetic constant, (H/m) | |
| Универсальная газовая постоянная, R (Дж/моль/К) | 8.314 | Universal gas constant, R (J/mol/K) |
| Постоянная Больцмана, k (Дж/К) | Boltzmann constant, k (J/K) | |
| Постоянная Стефана-Больцмана, (Вт/м²/К⁴) | Stefan-Boltzmann constant, (W/m²/K⁴) | |
| Константа смещения Вина, b (м·К) | 0.002897 | Wien’s displacement constant, b (m·K) |
| Лабораторная длина волны Hα (Å) | 6562.81 | Laboratory wavelength of Hα (Å) |
| Длина тропического года, T (сут) | 365.242199 | Tropical year length, T (days) |
| Стандартная атмосфера (Па) | 101 325 | Standard atmosphere (Pa) |
| Ослабление видимого света земной атмосферой в зените (минимально) | Visible light extinction by the terrestrial atmosphere in zenith (minimum) | |
| Показатель преломления воды при 20°C, n | 1.334 | Refractive index of water for 20°C, n |
| Момент инерции шара | Moment of inertia of a solid ball | |
| Площадь сферы | Area of sphere | |
| π | 3.14159265 | π |
| e | 2.71828183 | e |
| Золотое сечение, φ | 1.61803399 | Golden ratio, φ |
Data of some stars
Данные о некоторых звёздах / Data of some stars
| RA | DEC | S C | масса / mass | |||||
|---|---|---|---|---|---|---|---|---|
| Солнце | Sun | G2 | ||||||
| Альдебаран | Aldebaran | α Tau | K5 | |||||
| Альтаир | Altair | α Aql | A7 | |||||
| Антарес | Antares | α Sco | M1+B4 | |||||
| Арктур | Arcturus | α Boo | K1 | |||||
| Ахернар | Achernar | α Eri | B3 | |||||
| зв.Барнарда | Barnard’s star | Oph | M4 | |||||
| Бетельгейзе | Betelgeuse | α Ori | M1 | |||||
| Вега | Vega | α Lyr | A0 | |||||
| Денеб | Deneb | α Cyg | A2 | |||||
| Канопус | Canopus | α Car | F0 | |||||
| Капелла | Capella | α Aur | G5+G0 | |||||
| Полярная | Polaris | α UMi | F7 | |||||
| Процион | Procyon | α CMi | F5 | |||||
| Ригель | Rigel | β Ori | B8 | |||||
| Сириус | Sirius | α CMa | A1 | |||||
| Спика | Spica | α Vir | B1 | |||||
| Альфа Центавра | Alpha Centauri | α Cen | ; | G2 ; K1 | ||||
| Бета Центавра | Beta Centauri | β Cen | B1 | |||||
| Эпсилон Эридана | Epsilon Eridani | ε Eri | K2 |
Note for jury and team leaders
The proposed sketches are not full; the team leaders have to give more detailed explanations to students. But the correct solutions in the students’ papers (enough for 8 pts) may be shorter.
Basic criteria for examiners — Note
The given sketches are not full; the team leaders have to give more detailed explanations to students. But the correct solutions in the students’ papers (enough for 8 pts) may be shorter.
Условие
At what maximum distance from the Venus ecliptic the Earth can be visible in the sky from Venus (actually, from a point outside the Venus atmosphere)? Orbits of the planets may be considered circular.
Решение
The maximum space distance from the Earth to the Venus ecliptic is (see figure)
where is radius of the Earth orbit (1 AU), and is the orbital inclination of the terrestrial orbit to the plane of Venus ecliptic, which is evidently equal to the orbital inclination of the Venus orbit to the plane of the Earth’s ecliptic, i.e. .

In the Venetian sky, the Earth in such position can be visible at the maximum distance at the configuration of opposition, when the distance between Venus and Earth is minimal and equals to
(all angles are small and we do not take into account the inclination in these calculations). The maximal distance in the sky (angle ) may be found from the equation
Basic criteria for examiners.
Understanding the configuration, picture (may be not drawn but explained) — 3 pt.
Taking for solution correct values from tables — 1 pt.
Calculation of necessary distances — 2 pt.
Final result — 2 pt.
Теми и трудност
Трудност: неоценена.
Слънчева система · Планетни конфигурации
Предпоставки: Разширена олимпиадна подготовка
Оригинал в Архива: alphatheo.pdf · официални решения: theosol1.png · допълнителни данни: theosol2.png · допълнителни данни: theosol3.png · допълнителни данни: theosol4.png · допълнителни данни: theo_cr_1.png · допълнителни данни: theo_cr_2.png