Summing up the unique Venus Transit 2004 (VT-2004) programme


Vast public education project is an outstanding success

On June 8, 2004, Venus - the Earth's sister planet - passed in front of the Sun. This rare event - the last one occurred in 1882 - attracted the attention of millions of people all over the world.

In a few days' time, on November 5-7, 2004, about 150 educators, media representatives, as well as amateur and professional astronomers will gather in Paris (France) at the international conference "The Venus Transit Experience" to discuss the outcome of the related Venus Transit 2004 (VT-2004) public education programme ( This unique project was set up by the European Southern Observatory (ESO), together with the European Association for Astronomy Education (EAAE), the Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE) and the Observatoire de Paris in France, as well as the Astronomical Institute of the Academy of Sciences of the Czech Republic. It was also supported by the European Commission in the framework of the European Science and Technology Week, cf. ESO PR 03/04.

The VT-2004 programme successfully exposed the broad public to a number of fundamental issues at the crucial interface between society and basic science. It ensured the most comprehensive real-time coverage of the event via an extremely dynamic Central Display that was updated a short intervals. Thanks to the prior establishment of hundreds of mirror sites, the VT-2004 website was easily accessible all through the transit, even though it experienced about 55 million webhits during a period of 8 hours.

The VT-2004 programme established a wide international network of individuals (including school teachers and their students, amateur astronomers, interested laypeople, etc.) and educational institutions (astronomical observatories, planetaria, science centres, etc.), as well as 25 National Nodes with their own websites about the Venus Transit in as many local languages. It collected a large number of photos and drawings.

It also included an international Video Contest, inviting all interested parties to expose a theme around the transit, e.g., preparations for the event and the actual observations, as well as conveying the personal impressions. A professional jury has now selected the laureates among the many excellent entries (see the list below) who will present their videos at the Paris conference this week, competing for one of the top prizes, including a trip by the winning team to the ESO Paranal Observatory (Chile), home of the Very Large Telescope.

The "Venus Transit Experience" Conference

The Venus Transit Experience conference will take place at "Le Carré des Sciences" at the French Ministry of Research in Paris. It brings together the main participants in this project from many different European countries. A main aim is to discuss the impact of the project, identifying possible differences from country to country and showing how to share good practices in the future.

The VT-2004 programme provided an exciting field test for the execution of large-scale public activities relating to a particular, scientific event with strong operational constraints, including the requirement to act in real-time as this event progressed. Much valuable experience was gathered for future continent-wide activities involving the same mechanisms and carried out under similar conditions. Thus, the overall outcome of this unique public education project is clearly of very wide interest, not just in the field of astronomy.

The Distance to the Sun Remeasured

A central feature of the VT-2004 programme was the VT-2004 Observing Campaign , aimed at re-enacting the historical determination of the distance to the Sun (the "Astronomical Unit") by collecting timings of the four contacts made by participating observers and combining them in a calculation of the AU.

A large number of groups of observers registered; at the end, there were 2763 all over the world. Among these were almost 1000 school classes, demonstrating the large interest among students and teachers to participate actively in this unique celestial event.

As expected, not all groups delivered timing observations of the transit. In some places, the weather did not co-operate, some observers may have had instrumental problems, e.g., with the time signals, and others may not have felt confident to send in their measurements. Still, the resulting database is very comprehensive: before the stipulated deadline on July 10, 2004, no less than 4550 contact timings were received from 1510 registered observers!

The impressive outcome of this unique project is now available in a number of reports, accessible via the "VT-2004 Observing Campaign Results" webpage ( Following extensive analysis of this large material at Institut de Mécanique Celeste et de Calcul des Ephemerides (IMCCE; Paris), the resulting distance from the Earth to the Sun, based on the extensive observational data is:

1 AU = 149 608 708 km +/- 11 835 km
Difference from the "true" value of 1 AU: + 10 838 km

This result is only 0.007% larger than the currently accepted value, as determined by radar measurements (1 AU = 149 597 871 km), a splendid outcome of a truly unique international collaboration! A comparison with the results obtained by transit observations in past centuries shows that the above determination of the distance to the Sun in 2004 is the "best" in terms of accuracy, despite the relative lack of experience of most of the observers and notwithstanding a random distribution of the observing sites, caused by the absence in 2004 of any specific planning as this was done in earlier centuries. This success is undoubtedly due, above all, to more accurate timings and better known geographical locations, better optics in the telescopes, digital image recording and advanced image processing software.

In fact, even if we had not known the distance to the Sun before the Venus Transit 2004, we would have been able to measure it with an accuracy of one hundredth of a percent by means of the observations made on this occasion by the many participants all over the world!

The full text of this press release, with all weblinks, is available at:

Appendix: List of VT-2004 Video Laureates

Here is the list of Video Laureates (in alphabetic order) who will present their films at the "Venus Transit Experience" conference in Paris (November 5-7, 2004):

  • ...121 ans après - Dourbes, Belgium
  • The Big Black Dot - Poznan, Poland
  • Millennium Transit - Torun, Poland
  • Venus in Sole Visa - Praha, Czech Republik
  • Venus, the transit - Epinay-sous-Senart, France
  • Venus-Transit - Dresden, Germany
  • Venus Transit 2004 - Pisek, Czech Republic
  • Venus Transit 2004 - Teplice, Czech Republic
  • The Venus Transit in the Golden Valley - Hereford, UK
  • What's happening in Bialkow? - Wroclaw, Poland
  • The winners of the prizes will be announced at the VT-2004 website on Monday, November 8, 2004.

    Source: Eurekalert & others

    Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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