VENUS in transit Robert Wielinga Venus Evening star

VENUS in transit Robert Wielinga

Venus Evening star Goddess of love and beauty planet

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

Utrecht, june 8 th 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

Regularity in the occurance of transits of Venus 1631 1639 8 1761 1769 121 ½ 8 1874 1882 105 ½ 8 2004 2012 121 ½ 8 2117 2125 105 ½ 8

When Venus meets the earth Every 19 months the earth is overtaken by Venus 00 03 06 09 12 15 18 19

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

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

1996 2004 2012

Jeremiah Horrocks observes the transit of 1639

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

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

Captain James Cook Voyage. Tahiti 1769: with the Endeavour

Captain James Cook 1769: Tahiti

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

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

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

1874 / 1882 New hope: - Photography - Parallax of stars Cairo Rodriguez Is. Mauritius New Zealand

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

Exhibition in Museum Observatory Sonnenborh

VENUS Distance to the sun: 108 million km 0, 72 AU Diameter: 12. 104 km (0, 95 x earth) Massa: 4, 7 x 1024 kg (0, 80 x earth) Temperature (surface): 490 °C Pressure (surface): 90 atmosphere

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

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

Magellan spacecraft Launched from the Space Shuttle (1989)

Venera 13

A partial solar eclipse: the moon covers the sun

sunspot Mercury in transit in may 2003

Eclipse glasses Pinnhole projection Mirror projection

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

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