June 8: watch the Venus transit live
In the morning of June 8, 2004 - visible in the whole of Europe - we can witness a rare astronomical event: the passage of Venus in front of the Sun. This is indeed rare: the last passage took place in 1882 and was only seen partially in Europe.
Nederlandstalige versie / Version franaise reminder: Never look at the Sun without eye protection! Posted June 1, 2004
From 5u19 UT (7:19 local time) onwards, the planet Venus shall be visible as a moving black dot in the lower part of the solar disk. Venus will appear on the left and will glide away on the right at 13:23 UT, at the west side. During that period, the planet is located on one line with the Sun and the Earth. In 8 years from now on, they will be in the same configuration. After that, we have to wait until 2117...

The picture of the Sun on the left is taken by the Ukkel solar telescope in H-alpha. The picture on the right is the Sun in white light, the dark dots are the sunspots as they appear in the photosphere. Watching these pictures, you can witness the passage of Venus in real time. Click on the pictures to see an enlargement, they will be automatically refreshed every 60 seconds.

Back in 1761 and 1769, the passages of Venus were crucial for determining the distance between the Earth and the Sun, i.e. 1 Astronomical Unit (AU), the basis of all astronomical distances. Later, it turned out that these measurements were not so accurate as expected. The culprit was the black drop (gutta negra) effect that manifests itself at the moment Venus touches the solar disk. The value then obtained for the AU, which can now be determined with much higher precision using modern techniques, was however a reasonable guess.
You can catch a movie of
Have a look at a website, Dutch/ French offering an overview of activities organised by the planetarium and the Royal Observatory of Belgium in the framework of the Venus Transit.