VENUS

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VENUS in transit
Robert Wielinga
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Venus
Evening star
Goddess of love and beauty
planet
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Utrecht, june 8th 2004, 05 h 20 m sunrise
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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
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Regularity in the occurance of transits of Venus
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When Venus meets the earth
Every the earth is overtaken
by Venus
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When Venus meets the earth
But the orbit of Venus is tilted slightly with
respect to orbit of the earth around the sun
(3,4o).
No transit
Usually when Venus overtakes the earth there is
no exact alignment
Exact alignment very rare!
Transit!
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2002
dec
1998
jan
nov
feb
oct
mar
sep
1999
2001
apr
aug
may
jul
jun
1996
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1996 2004 2012
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Jeremiah Horrocks observes the transit of 1639
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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
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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
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Captain James Cook
Voyage with the Endeavour
1769 Tahiti
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Captain James Cook
1769 Tahiti
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The unfortunate adventures of Guillaume-Joseph-Hya
cinthe-Jean-Baptiste Gentil de la Galaisière (Le
Gentil)
maart 1760
mei 1761
6 juni 1761
juli 1760
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The unfortunate adventures of Guillaume-Joseph-Hya
cinthe-Jean-Baptiste Gentil de la Galaisière (Le
Gentil)
okt 1771
mrt 1768
aug 1766
mrt 1770
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• Problems in 1761 / 1769
• Weather (Le Gentil)
• Longitude
• The BLACK DROP effect

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• 1874 / 1882
• New hope
• Photography
• Parallax of stars

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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
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Exhibition in Museum Observatory Sonnenborh
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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
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The atmosphere is is composed mostly of carbon
dioxide. There are several layers of clouds, many
kilometers thick, composed of sulfuric acid.
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Mikhail Lomonosov, june 5, 1761 discovered,
during a transit, that Venus has an atmosphere
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Magellan spacecraft
Launched from the Space Shuttle (1989)
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Venera 13
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A partial solar eclipse the moon covers the sun
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sunspot
Mercury in transit in may 2003
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Mirror projection
Eclipse glasses
Pinnhole projection
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Projection method safe and handy!
With binoculars (only use one half) or
telescope
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Links www.sonnenborgh.nl www.venusovergang.nl
(nog niet aktief) home.hetnet.nl/smvanroode/venu
stransit www.venusovergang.be www.vt-2004.org