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The history and science of the Transit of Venus
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The history and science of the Transit of Venus

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  • 1. 太白金星Venus Credit: Juan Manuel Pérez Rayego
  • 2. 全天第三亮 的天體 Fred Espenak Doug Zubenel (TWAN)
  • 3. 晨星/昏星 大距Venus Feb - Sep 2010 Cenk E. Tezel & Tunc Tezel
  • 4. 內行星 vs 外行星 上合合 西大距 衝東大距 下合
  • 5. 罕有的金星凌日 • 1631 December 7 • 1639 December 4 121.5 years • 1761 June 6 • 1769 June 4 105.5 years • 1874 December 9 • 1882 December 6 121.5 years • 2004 June 8 • 2012 June 6 105.5 years • 2117 December 11 Last chance in your life!
  • 6. 金星與 地球的 軌道 3.4° 夾角軌道周期: 地球與金星金星 224日 的會合周期:地球 365日 584日 (1.6年)
  • 7. Paper Plate Educationhttp://analyzer.depaul.edu/paperplate/
  • 8. 2012年6月6日 金星凌日 凌日階段 時間 太陽方向/方位角/仰角 日出 5時37分 東北偏東/065°/0° Ⅰ 凌始外切 6時11分 東北偏東/068°/6° Ⅱ 凌始內切 6時29分 東北偏東/069°/10° 不按比例 凌甚 9時31分 西北偏西/081°/51° 注意選擇適當的觀測地點 Ⅲ 凌終內切 12時31分 西北偏西/278°/88° Ⅳ 凌終外切 12時48分 西北偏西/274°/84°
  • 9. 哥白尼 Nicolaus Copernicus (1473-1543) 天體運行論, 1543 De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres)
  • 10. Thomas Digges, 1556 Thomas Trevelyon, 1608 "The true proportion of all the Planets"
  • 11. 第谷Tycho Brahe(1546-1601)
  • 12. 開普勒 Johannes Kepler (1571-1630)
  • 13. Kepler’s laws of planetary motion• Law of ellipses – the orbit of a planet about the sun is an ellipse with the sun at one focus• Law of equal areas – a line joining a planet and the sun sweeps out equal areas in a equal intervals of time• Law of harmonies – the square of a planet’s sidereal period around the sun is directly proportional to the cube of the length of its orbit’s semi-major axis, a
  • 14. The Rudolphine Tables by Johannes Kepler, 1627
  • 15. Kepler predicted the Transit of Mercury on Nov 7, 1631 and Transit of Venus on Dec 6, 1631
  • 16. 行星與太陽平均距離 (以天文單位計算) Copernicus Kepler 20th CenturyMercury 0.3763 0.389 0.387Venus 0.7193 0.724 0.723Earth 1.0000 1.000 1.000Mars 1.5198 1.523 1.524Jupiter 5.2192 5.200 5.202Saturn 9.1743 9.510 9.539 1天文單位 (AU, Astronomical Unit) = 太陽與地球的距離
  • 17. Pierre Gassendi (1592-1655)• French observed Transit of Mercury on Nov 7, 1631• name "Aurora Borealis"
  • 18. Angular size VS real sizea much bigger solar system!
  • 19. Jeremiah Horrocks (1618 - 1641) • British • predicted and observed the transit of Venus on Dec 4, 1639
  • 20. The only 2 people saw the Transit of Venus in 1639Jeremiah Horrocks William Crabtree
  • 21. Cosmotheoros by Christiaan Huygens, 1698
  • 22. 1 AU = ? When Who How 1 AU =3rd c BCE Aristarchos geometry 1,200 Earth Radius2nd c CE Ptolemy " " 1,160 Earth Radius1540 Copernicus " " 1,142 Earth Radius1600 Tycho picked value halfway between 1,150 Earth Radius Copernicus and Ptolemy1620 Kepler chose value 3,600 Earth Radius1672 Richer & measured parallax of Mars 21,000 Earth Radius, or Cassini 140,000,000 km
  • 23. Method 1 – a smarter(?) guess• Measure the apparent size of a planet with a telescope• Assume a physical size of the planet• Distance to the planet can be obtained from the ratio of physical size to the apparent angular size It is practically accessible, but theoretically no better than pure guess
  • 24. Method 2 – triangulation (parallax)• If a planet is observed simultaneously by two observers separated by large distances, then the apparent position of the planet among the background stars would be slightly different.• If we know the separation of the two observers, the distance to the planet can be calculated.• Difficulties: measure of the separation, the longitude problem, small angle, synchronization of the clocksIt is prefect in theory, but difficult toexecute 32
  • 25. 哈雷 Edmond Halley (1656 – 1742)• observed Transit of Mercury in 1677 St Helena island
  • 26. not to scaleParallax視差
  • 27. Two pictures of the transit of Venus were taken simultaneously from Essen in Germany and Uis in Namibia on 8 June 2004.
  • 28. A的時間短於B的時間 B 比 A 早見凌始 但 A 比 B 早見凌終
  • 29. I recommend it therefore again and again tothose curious astronomers who (when I amdead) will have an opportunity of observingthese things, that they would remember thismy admonition, and diligently applythemselves with all their might in making thisobservation, and I earnestly wish them allimaginable success: in the first place, that theymay not by the unseasonable obscurity of acloudy sky be deprived of this most desirablesight, and then, that having ascertained withmore exactness the magnitudes of theplanetary orbits, it may redound to theirimmortal fame and glory.
  • 30. Map of theSolar System,AtlasCoelestis ofJohannDoppelmayr.Published in1742.
  • 31. The red dots represent expeditions of 1761 and 1769.Location: Expedition leader, Nationality1 = Cape of Good Hope : Mason & Dixon, British (1761)2 = St. Helena : Maskelyne, French (1761)3 = Rodrigues Island : Pingré, French (1761)4 = Tobolsk, Russia : Chappe, French (1761)5 = St. John’s, Newfoundland : Winthrop, British (1761)6 = Tahiti : Cook, British (1769)7 = Pondicherry, India : Le Gentil, French (1769)8 = Cabo San Lucas, Mexico : Chappe, French (1769)9 = North Cape, Norway : Bayley, British (1769)10 = Haiti : Pingré, French (1769)11 = Hudson Bay, Canada : Dymond, British (1769)
  • 32. 經度問題
  • 33. Sketch of the 1761 transit as seen by Nicholas Ypey.
  • 34. 1 AU = ? When Who How 1 AU =3rd c BCE Aristarchos geometry 1,200 Earth Radius2nd c CE Ptolemy " " 1,160 Earth Radius1540 Copernicus " " 1,142 Earth Radius1600 Tycho picked value halfway between 1,150 Earth Radius Copernicus and Ptolemy1620 Kepler chose value 3,600 Earth Radius1672 Richer & measured parallax of Mars 21,000 Earth Radius, or Cassini 140,000,000 km James1761 Transit of Venus 125.3 -154.8 million km Short
  • 35. Captain Cook
  • 36. Samuel Dunn (d. 1794)"A Determination of the exactMoments of Time when thePlanet Venus was at externaland internal contace with theSuns Limb…,". Philosophicaltransactions of the RoyalSociety of LondonLondon: Lockyer Davis, 1771.Volume LX (1770)
  • 37. 1 AU = ? When Who How 1 AU =3rd c BCE Aristarchos geometry 1,200 Earth Radius2nd c CE Ptolemy " " 1,160 Earth Radius1540 Copernicus " " 1,142 Earth Radius1600 Tycho picked value halfway between 1,150 Earth Radius Copernicus and Ptolemy1620 Kepler chose value 3,600 Earth Radius1672 Richer & measured parallax of Mars 21,000 Earth Radius, or Cassini 140,000,000 km1761 James Short Transit of Venus 125.3 -154.8 million km Richard1769 Transit of Venus 148.1 – 154.8 million km Proctor Reanalysis the data of Transit of1822 Johann Encke 153,300,000 km Venus
  • 38. A new size of the solar system• From the transit of Venus on June 3, 1769, the AU was measured to 10% accuracy.• The size of the solar system turned out to be 100 times larger than Ptolemy’s estimate.• Once the absolute scale (AU) is fixed, then the size and distances to the planets can be determined.• The physical size of the solar system is finally known. Estimates of the size of Earths orbit, 1 AU = 149,598,000 kilometers A.D. 100 - 1769 Coming of Age in the Milky Way, Timothy Ferris
  • 39. The blue dots represent expeditions of 1874 and 1882.Location: Sponsoring nations1 = Vladivostok, Russia : United States, Russia (1874) 13 = Rodrigues Island : Britain (1874)2 = Nagasaki, Japan : United States (1874) 14 = St. Paul’s Island : France (1874)3 = Beijing, China : United States, Germany, Russia, France (1874) 15 = Campbell Island : France (1874)4 = Kerguelen Island : United States, Britain, Germany (1874) 16 = Yokohama, Japan : France, Mexico (1874)5 = Tasmania : United States (1874) 17 = Calcutta, India : Italy (1874)6 = New Zealand : United States (1874, 1882), Britain (1874) 18 = Tashkent, Uzbekistan : Russia (1874)7 = Chatham Island : United States (1874) 19 = Reunion Island : Netherlands (1874)8 = Auckland Islands : Germany (1874) 20 = South Africa : United States, Britain (1882)9 = Mauritius : Britain, Germany (1874) 21 = Santa Cruz, Argentina : United States (1882)10 = Isfahan, Iran : Germany, Russia (1874) 22 = Santiago, Chile : United States (1882)11 = Cairo, Egypt : Britain, Russia (1874) 23 = Algeria : France (1882)12 = Hawai’i : Britain (1874) 24 = South Georgia : Germany (1882)
  • 40. 1874 北京 - James Craig Watson
  • 41. 1 AU = ? When Who How 1 AU =3rd c BCE Aristarchos geometry 1,200 Earth Radius2nd c CE Ptolemy " " 1,160 Earth Radius1540 Copernicus " " 1,142 Earth Radius1600 Tycho picked value halfway between 1,150 Earth Radius Copernicus and Ptolemy1620 Kepler chose value 3,600 Earth Radius1672 Richer & measured parallax of Mars 21,000 Earth Radius, or Cassini 140,000,000 km1761 James Short Transit of Venus 125.3 -154.8 million km Richard1769 Transit of Venus 148.1 – 154.8 million km Proctor Reanalysis the data of Transit of1822 Johann Encke 153,300,000 km Venus1874 David Todd Transit of Venus 148,098,000 km
  • 42. 4 ways of calibrating AU using ToV1. Observing the different apparent paths of Venus across the face of the Sun seen from different widely spaced latitudes2. Measuring the rate (angular velocity) at which Venus crosses the face of the Sun. The rate is the vector sum of the orbital angular velocity of Venus and the Earth and the angular velocity of the observing site due to the Earth’s daily rotation.3. Comparing the absolute times of Venus’s contact with the Sun’s limb, seen from different places on Earth (Delisle’s method).4. Comparing the total time for Venus to cross the Sun as seen from different latitudes, which depends on both the curvature of the Sun’s limb and the distance moved by the observer due to the Earth’s rotation (Halley’s method).
  • 43. 警告:太陽觀測活動必須注意安全不正確觀測太陽會導致永久失明
  • 44. 智能手機 計時 apps
  • 45. Two coming historical events 5月21日日環食 香港可見 : 日出至 07:16 環食: 06:07 – 06:10
  • 46. 2012年6月6日 金星凌日 凌日階段 時間 太陽方向/方位角/仰角 日出 5時37分 東北偏東/065°/0° Ⅰ 凌始外切 6時11分 東北偏東/068°/6° Ⅱ 凌始內切 6時29分 東北偏東/069°/10° 不按比例 凌甚 9時31分 西北偏西/081°/51° 注意選擇適當的觀測地點 Ⅲ 凌終內切 12時31分 西北偏西/278°/88° Ⅳ 凌終外切 12時48分 西北偏西/274°/84°
  • 47. 講座系列 時間:下午3時-4時30分 地點:香港太空館演講廳 第一講:金星凌日的科學與歷史 日期:2012年5月13日(星期日) 講者:張師良先生(香港大學理學院科學導師)第二講:金星凌日及日環食現象及觀測日期:2012年5月20日(星期日)講者:余惠俊先生(香港天文學會外務副會長) 第三講:金星 日期:2012年5月27日(星期日) 講者:張師良先生(香港大學理學院科學導師)第四講:太陽系外的凌日現象日期:2012年6月2日(星期六)講者:李文愷博士(香港大學物理系副教授)
  • 48. 6月6日觀測活動 • 尖沙咀星光大道 • 06:00 - 13:00 • 小型觀測站在網頁公佈 • 網上直播www.facebook.com/transitofvenushktransitofvenus.hkhk.space.museumroadshow.science.hku.hk

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