Exactly 1yr, 1month & 1day after Mercury, on the morning of Tuesday 8th June 2004 the planet Venus (pictured left) took its turn to be in transit (or passage) across the face of the Sun. Because Venus goes round the Sun much more slowly than Mercury, transits of Venus are among the rarest of planetary alignments: only six such events have occurred since the invention of the telescope (1631, 1639, 1761, 1769, 1874 & 1882) and no living person had seen one before this. Transits occur in pairs separated by 8yrs, with pairs recurring at intervals of 121.5 and 105.5yrs, so if you missed this one you had a chance to redeem yourself in 2012 though the full duration was not visible in the UK. It's a very long wait after that, however!
The transit was due to start at about 6:20BST in England, be of maximum extent at around 9:20 and end by 12:25. Experience with the Mercury transit had indicated that the only convenient viewing position for my refractor telescope suffered from obscuration by trees, but due to the higher position of the Sun in the sky this would clear at about 8:30am. Conversely, due to the longer duration of this transit, the house roof would come into play before the end! This would still give an adequate viewing period though so I decided to persist with the projection method but this time used a translucent screen supported on music stands (necessity being the mother of invention!) in an attempt to avoid many of the distortions experienced when photographing the Mercury transit.
Since the previous transit I had been experimenting with astro-photography using a digital web-cam through my recently-acquired 114mm reflector, so I was intending to use this instrument as well as the refractor. The web-cam connects to a laptop computer which has to be in shade to see anything on the screen so I blacked out the garage and passed the lead in through the window. I had marked out a number of viewing locations with chalk dots (the reflector has an equatorial mount, which needs correct alignment, so marking the required position of the tripod legs well before the event saved a lot of time!) and hoped to view almost the entire event as the trees weren't so much of a problem (not after a bit of surreptitious pruning, anyway!). Whether I would be able to capture the passage of Venus onto the Sun's disc (1st & 2nd contact) was not certain though as the garden wall threatened to intrude: only time would tell!
Rising at 5:45am I was relieved to see a cloudless sky, and luckily this persisted throughout the morning with only a few wisps of high cloud. My preparations all proved to have paid dividends and I was very glad to see the shadow of the garden wall clear the reflector tube at around 6:10am. Bearing in mind the relatively slow progress of Venus across the Sun I had decided to take one photo every 10mins with each of the cameras, offset by 5mins relative to each other. This meant I was dashing from the house to the garage and back almost continuously for over 3hrs in the hot Sun! The web-cam didn't always behave itself but on the whole I was pleased with the outcome. The projection screen worked very well and I was able to take a good set of well-aligned shots with few difficulties. In both cases little computer manipulation was required apart from contrast adjustment and image rotation, but due to the number of images taken (about 125 in total) it all took rather a long time! For further details as to how I achieved all this, see the Technical Info page.
Although the next transit after this one was actually on 6th June 2012, only the very end was visible at sunrise from England. The same will be true in 2117 so if you missed the 2004 event I'm afraid you've blown it, as your next opportunity to see a full transit won't be until 8th December 2125!
 | Pictures of the Transit | | Technical Info |
| Animations | |||||||
| Venus entering the Sun's disc |
| Venus crossing the Sun (naked-eye view) |
| Venus leaving the Sun's disc |
||
As mentioned above, the next transit after 2004 was in 2012 - at dawn on Wednesday 6th June, to be precise. Only the last part would be visible in the UK but even this would be worth observing so I began making my plans early.
Because the transit would be in progress as the Sun rose and end when it was less than 10degrees above the horizon, I needed a high vantage point in order to get a clear view. The obvious choice was the church tower, but getting all the equipment up there was not going to be easy! In addition, there was no source of power for the camera or laptop. I thus took advantage of a clear evening a couple of days prior to "transit day" to deploy a long extension lead inside the tower and move everything up as high as I could - to the bell-chamber in fact! I then aligned the equatorial mount in a number of alternative sites on the roof and marked the positions of the legs with chalk so I could quickly set things up on the day. On the evening of the 5th I packed a rucksack with camera, tripod, laptop, torches, solar filters and power supplies; laid out warm clothing; set my alarm for 4am, and headed for bed!
Unfortunately, the weather forecast for dawn was not promising, with a band of rain and cloud predicted to be lying across East Anglia until mid-morning. I had hoped it might move through more quickly than forecast, but in fact it slowed somewhat so we had rain through the night. While this had almost stopped by the time I was climbing the 112 narrow steps up the tower, all my chalk marks had been washed away! However, this didn't really matter as the entire sky was obscured with thick grey cloud, making it highly unlikely I would see anything at all. In fact, conditions didn't get any better for several hours so by the time the transit ended just after 5:50am I hadn't even been able to deduce where the Sun was in the sky, let alone notice whether it had a black dot on it! I thus abandoned my vigil and began the strenuous task of moving everything back down to ground level again - a spot of vigorous exercise I could well have done without at that time in the morning!
I thus had to console myself with the thought that at least I had had perfect conditions for the full transit in 2004 when few in the UK were so lucky. However, a few hours later this time would have made all the difference! Still, that's the British weather for you. I also considered the fact that we in Laxfield had a beautiful day for our excellent Diamond Jubilee Street Party on Monday 4th, an event which is actually more unusual than a transit of Venus! The last one was way back in 1897, all of 115yrs ago, whereas the average interval between pairs of transits is 113.5yrs!! Looking on the bright side is, of course, another famous British trait.
