IAO 2012, Теория, старша възраст — Задача 1. Transit of Venus
XVII International Astronomy Olympiad — Theoretical round — Group β
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
Recently, on June 6, 2012, an infrequent astronomical phenomenon, transit of Venus across the solar disc, took place. The next transit of Venus will take place only in 2117. Calculate the date of that transit. (Answer without calculations will not be considered even as a partial solution.)
Решение
Any transit of Venus may occur only in configuration of inferior conjunction of Venus.
To calculate next inferior conjunctions we need first to find the synodic period of Venus:
where and are the sidereal periods of Venus and Earth respectively,
January 1, 2117 will be in days after June 6, 2012.
December 31, 2017, respectively, will be in days after that date.
It means that the close approach of Venus in 2117 will be after 66 synodic periods of Venus.
38538 days are 20 days earlier than the date 38558 that we calculated for December 31, 2117. Thus, 38538 days after June 6, 2012 corresponds to December 11, 2117.
Answer: The next transit of Venus will take place on December 11, 2117.
Basic criteria for examiners.
Transit of Venus may occur only in configuration of inferior conjunction of Venus — 2 pt.
Will be after integer number of synodic period of Venus — 1 pt.
Formula and calculation of synodic period of Venus — 2 pt.
Calculation of number of days till the inferior conjunction of Venus in 2117 — 1 pt.
Final answer — 2 pt.
Теми и трудност
Трудност: неоценена.
Небесна механика · Синодични периоди
Предпоставки: Разширена олимпиадна подготовка
Оригинал в Архива: betatheo.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