The Andromeda Observatory

The Event:

A report and images of the Transit of Venus recorded from Sheffield City Centre Peace Gardens on June 8th 2004.

It was an amazing day from start to finish as some 5,000 people came in person and over 65,000 joined in on the web with many more listening in live on BBC Radio Sheffield. With a grant provided by South Yorkshire Key Fund , we were able to set up in the Peace Gardens in Sheffield city centre to watch the planet Venus transit the Sun for the first time in 122 years.

Two large TV screens were set up inside a marquee to safely show the public the view of the planet crossing the Sun's disc. Images came live from cameras attached to the back of several telescopes and were also transmitted directly onto the Internet. It wasn't long before large queues began to form as people waited eagerly to catch a glimpse of the unfolding spectacle. Visitors were kept entertained both inside and outside the marquee by the attendant astronomers who were explaining what was going on.

By mid-morning the queueing times had reached some 20 minutes or so but despite temperatures of almost 30°C in the shade the enthusiasm didn't wane. Our guest of honour, the Lord Mayor of Sheffield, Diane Leek arrived at 9am and was quick to praise our efforts.

The event had already been promoted in a Sheffield Hallam University press release but we had a further, unexpected, boost. We received a great deal of coverage by the national media, including announcements of our presence on morning television and the crowds continued to gather right the way through to the end of the transit. The excellent coverage meant that numbers dropped off rapidly after Venus had disappeared but replays of the event were provided until mid-afternoon for any latecomers.

As registered members of the European Southern Observatory VT-2004 Observing Campaign , our observations of the transit times have been passed on and added to other results worldwide. This effort has resulted in a remarkably accurate value for the Earth-Sun distance of 149,605,264km, within 0.005% of the accepted figure.

All in all, the day was a complete success and most of all we were able to bring a great deal of enjoyment to thousands of people around the world.

And our favourite comment from the guestbook...

"The best transit of Venus I have ever seen" - priceless!

The Technology:

Because of the inherent dangers of looking at the Sun, the decision was taken from the start to provide views of the transit on screens via cameras attached to the back of the telescopes. As the idea developed it became more and more complicated as several cameras would need to be controlled with only one view being shown on screen at any given time. Since there were no guarantees that the transit would actually be visible due to cloud cover the Internet was introduced as another source to provide images from elsewhere if needed. Once the Internet had been introduced into the equation we then decided to transmit our own pictures on the web too.

The challenge was to be able to provide all this from a marquee in a park in the centre of Sheffield.

Web cameras were used to take the images from the telescopes, with each one requiring its own PC to control it. Just to add to the variety a number of cameras were also dotted about overlooking the event itself. To show the image from a particular camera, all thes PCs were connected together over a local area network. Another PC was then employed as a server to coordinate the images and determine which one would be output to yet another PC controlling the main view screen. The server was also used to send the selected image to the Internet. Sites on the web providing images were treated as just another camera by the software.

The Internet connection was important mainly because it would allow the transit to be viewed whatever the weather. To be able to connect at all required a large radio transceiver on the outside of the marquee linked to one of the local University computer networks. All that was needed then was some software to control it all.

The system was developed by James O'Neill and myself. The hardware was dealt with by James whilst I was responsible for the software. Several test runs were carried out leading up to the event, the most notable being a dress rehearsal during the annual Mayfield Open Day. That enabled many potential problems to be identified and contingencies drawn up.

On the day, the whole set up worked flawlessly. Images from Switzerland and Portugal were shown on the main screen very early on as cloud blocked the view from Sheffield. The weather soon improved though and for the rest of the transit our own pictures were shown both to the Sheffield public and many thousands of others around the world on a number of sites on the web.

In Pictures: