1. VENUS in transit Robert Wielinga

2. Venus Evening star Goddess of love and beauty planet

3. Utrecht, june 8th 2004, 05 h 20 m : sunrise

4. Utrecht, june 8th 2004, 07 h 19 m : a black dot passes in front of the sun I : first contact at 07 h 19 m II: seccond contact at 07 h 39 m III: third contact at 13 h 03 m IV : fourth contact at 13 h 23 m A transit of Venus: a mini solar eclipse

5. 1631 1639 1761 1769 1874 1882 2004 2012 2117 2125 88888 121 ½ 105 ½ Regularity in the occurance of transits of Venus

6. months 00030609 12151819 When Venus meets the earth Every the earth is overtaken by Venus

7. No transit Transit! But the orbit of Venus is tilted slightly with respect to orbit of the earth around the sun (3,4 o ). Usually when Venus overtakes the earth there is no exact alignment Exact alignment: very rare! When Venus meets the earth

8. jan dec feb mar apr may jun jul aug sep oct nov 1996 1998 1999 2001 2002

9. 19962004 2012

11. Jeremiah Horrocks observes the transit of 1639

12. William Crabtree (friend of Horrocks) is the seccond person to observe the 1639 transit “I beseech you, therefore, with all my strength, to attend to it diligently with a telescope and to make whatever observation you can….” Horrocks, in a letter to Crabtree

13. A A B B The path of Venus acros the sun by observers A and B as seen from the earth Halley (1656-1742) proposed a method to measure the ‘immense distance to the sun’ by international coordinated observations during the transit of 1761.  

15. Voyage with the Endeavour Captain James Cook 1769: Tahiti

16. Captain James Cook 1769: Tahiti

17. The unfortunate adventures of Guillaume-Joseph-Hyacinthe-Jean- Baptiste Gentil de la Galaisière (Le Gentil) maart 1760 juli 1760 mei 1761 6 juni 1761

18. mrt 1768 mrt 1770 okt 1771 aug 1766 The unfortunate adventures of Guillaume-Joseph-Hyacinthe-Jean- Baptiste Gentil de la Galaisière (Le Gentil)

19. Problems in 1761 / 1769: - Weather (Le Gentil) - Longitude - The BLACK DROP effect

20. CairoRodriguez Is.MauritiusNew Zealand 1874 / 1882 New hope: - Photography - Parallax of stars

21. Members of the Dutch expedition in 1874 in front of their accommodation in St. Denis, Réunion Observation camp of the Dutch expedition 1874: Dutch participation !

22. Exhibition in Museum Observatory Sonnenborh

23. VENUS Distance to the sun: 108 million km 0,72 AU Diameter: 12.104 km (0,95 x earth) Massa: 4,7 x 10 24 kg (0,80 x earth) Temperature (surface): 490 °C Pressure (surface): 90 atmosphere

24. The atmosphere is is composed mostly of carbon dioxide. There are several layers of clouds, many kilometers thick, composed of sulfuric acid.

25. Mikhail Lomonosov, june 5, 1761 discovered, during a transit, that Venus has an atmosphere

26. Magellan spacecraft Launched from the Space Shuttle (1989)

30. Venera 13

31. A partial solar eclipse: the moon covers the sun

32. Mercury in transit in may 2003 sunspot

33. Eclipse glasses Pinnhole projection Mirror projection

34. Projection method: safe and handy! With binoculars (only use one half) or telescope

35. Links: www.sonnenborgh.nl www.venusovergang.nlwww.venusovergang.nl (nog niet aktief) home.hetnet.nl/~smvanroode/venustransit www.venusovergang.be www.vt-2004.org