European Southern Observatory (ESO)European Association for Astronomy Education (EAAE) Observatoire de ParisInstitut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE)Astronomical Institute of the Academy of Sciences of the Czech Republic The Venus Transit 2004 European Science & Technology Week 2004Visit the websites of the VT-2004 organisers

The Venus Transit 2004

... How to Participate Actively!

A unique opportunity!

On the day of the Venus Transit, Tuesday, June 8, 2004, you will be able to follow on the the web live observations of the event, as recorded with large professional and smaller amateur telescopes . A selection of real-time images will be available via the central VT-2004 display page .

The VT-2004 website will help you to enjoy this event even more, by providing you with information and possibilities for active participation. For instance, you may:

  • learn more about the background of the Venus Transit from the numerous Brief and Extended InfoSheets
  • do your own observations
  • participate in the Video Contest and possibly win one of the prizes
  • submit a drawing for the Art Gallery (mostly for younger people)
  • register officially with the VT-2004 observing campaign and participate in the measurement of the distance between the Earth and the Sun (see below)

Whatever you choose to do, we wish you much fun and not least, clear skies at the time of Venus Transit on June 8, 2004!

The VT-2004 observing campaign

Many interested individuals and groups in different geographical regions will do their own observations. They will thereby have the exciting opportunity to join the VT-2004 Observing Campaign and to participate actively in this programme . On the present page, you will find more information on how this is possible.

We strongly urge you to consider taking part in this unique, modern re-enactment of a famous historical observation which was used by observers in the 17th, 18th and 19th centuries to measure the distance between the Earth and the Sun . By establishing a large network of active VT-2004 observers, it will become possible to illustrate this extraordinary international collaboration directly on a dedicated webpage and also to provide a running estimate of the resulting value of this distance. Details will be posted in due course on the VT-2004 "Central Display" page.

You will find a map with the geographical positions of the observers that have registered so far on this page. It also shows how many there are in different categories (schools, clubs, inidividuals, etc.).

How to participate actively in the VT-2004 observing campaign

If you find this opportunity interesting and would like to join the VT-2004 observing campaign - here is how you should proceed. Please read on.

1. What kind of observation am I supposed to do?

The goal of each observer is to measure the time(s) when Venus crosses the border(s) of the solar disk. You should this as accurately as your equipment allows. Detailed instructions are available on the observations' page .

Since it is important that you "use the correct time", we suggest that you familiarize yourself with the VT-2004 InfoSheet about "Universal Time" . Irrespective of your observing method, you will have to deliver the times you determine in Universal Time !

Moreover, whatever equipment and whatever observing method you use, we urge you to read the Safety Instructions!

2. Preparations for the observations

You should decide where you intend to do the observation on June 8, 2004 . From your backgarden? In (or near) which town? At a remote site?

Then you should determine the geographic longitude and latitude of your observing site. There are various ways of doing this, e.g.:

  • If you have access to a GPS (Global Positioning System) device, place yourself at the observing site and read the values indicated on the display. You may learn more about Navigation and GPS here.
  • Look at a local map on which the geographical longitude and latitude are indicated. Try to measure the position of your observing site with a reasonable accuracy.
  • Consult the website to find the geographical longitude and latitude of the (nearest) town. This database is very large - it contains accurate positions of over 2 million towns, so the chances that you will find your place are quite good. Please note that you will have to register (with username and password) in order to access this site.

Note that for longitude, "East" means east of the Greenwich meridian - most locations in Europe and Africa, and all in Asia and Australia therefore have eastern longitudes.

What equipment and observing method are you going to use? Will you project an image of the Sun on a screen? Will you use a camera? Is it already available or will you have to build (buy) it?

3. Registration with the VT-2004 observing campaign

In order to join officially the VT-2004 observing campaign, you must now register on the VT-2004 observing campaign interface page . Please follow the link below. You will be asked about:

  • your identification
  • your observing site (with the longitude and latitude you have already determined - this is very important!)
  • your observing method

Note that if you (and your group) intends to use more than one instrument, you must make one registration for each observing instrument. This is because each registration will allow you to later provide the central site with one observation. Use the button below (and then register via "Join the VT-2004 Campaign"). Information about the privacy policy is available at that site.

Your registration will be confirmed. Once registered, you will receive a progress report at regular intervals from the VT-2004 central site. You may edit your registration data at any time by logging in again.

Join the VT-2004 Observing Campaign

4. Delivery of the observations

On the day of the Venus Transit (June 8, 2004), you will perform the timing observations, as indicated on the observations' page .

Once they are ready, you should send your results (timings) as soon as possible to the central VT-2004 computer. This should be done via the VT-2004 Interface webpage . You will find the necessary instructions there.

The receipt of your observation(s) will be immediately confirmed and you will receive additional information about the accuracy you achieved, etc. You will be able to follow on the special webpage, how observations from observers in many different geographical regions are delivered and how they all contribute to the computation of the distance to the Sun. Information about how this will be done is available here.


We look forward to receiving your registration soon. We will provide information about the number of registrations etc. from time to time via the Latest News page (and on the VT-2004 top page).

If you have questions in this connection, you may contact the organisers via email at