Epilogue 2004 |
| Importance |
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| What importance has the Venus transit today? From the scientist's look it's zero. Most important on this phenomenon is its rarity and magnificence.
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| How did we measure |
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Work on observational device wasn't easy and without problems. In unison we decided to use method of regressive projection - picture from telescope is projected on white surface (eg. piece of clean white paper). The phenomenon isn't recorded directly from the Sun but from this projection. Its main advantage is that you can throw away doubts about damaging the cameras. Also you don't need any filters. This method is quite difficult in matter of building the apparatus.
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| How did we work |
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In school physical store we found old telescope. Unfortunately it was the best we could find, so we started preparations with it. As a tripod we used pedestal from projector extended with 50 cm long metal bar. This way we got the telescope some 150 cm high.
Then came the worse part of the work. We had to attach projecting screen to telescope and make sure that its position will be in one line with the telescope.
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| First success |
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Then the leader of project came with first photographies of regressive projection. "It really works", we were satisfied. These pictures were taken during 30 seconds of direct sunshine (It was a cloudy day). "It was quite easy," he says. In one hand he held a binocular and in the other hand he had a digital camera. He projected the Sun first on white screen and then on a black one. It was quite an important experience and we gained many pieces of knowledge for further work.
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| How did it look like? |
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For optimal size of the disk, we decided for about 20 cm. Projecting screen itself was on bottom of the carton box, which was about 60 cm deep. This box was placed on metal bars (connected with telescope) about 120 cm far from the lens. Whole telescope was covered by 'sail', so we got larger contrasts.
Observation took place on meteorological observatory on hill Milesovka (836,6 meters above sea). Thanks to our place, we had perfect sight to each direction. Projection was recorded with two digital cameras and two video cameras. All records were then adjusted and redrawn with help of computers. Because of ability of digital cameras to catch even almost unrecognizable sunbeam, we were able, after the color correction, to get surprising results.
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| What happened on 8th June |
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Whole transit of Venus lasted for about 6 hours, the most interesting things happened during first and last twenty minutes. Venus appeared at lower edge of the Sun circle at 7 hours 19 minutes and 49 seconds (daylight-saving DST). Let us add that these times are from our own measuring and they can slightly differ from correct time.
Venus overlaid the Sun at 7 hours 39 minutes and 34 seconds. In this time we had chance to see black droplet effect. Black shape was whole on the Sun disc but we could see some black joint coming from the shape towards the edge of the Sun - it's the combination of unstable Earth atmosphere and curving effects in telescope.
Next few hours Venus traveled over the Sun towards the right edge. In that time we were able to see the planet even without a telescope. Her angle diameter, which is about 1 minute, guarantees that Venus will be visible without any optical help. For whole time the Venus was visible as a black dot.
At 13 hours 3 minutes and 38 seconds, Venus made its third contact, inner contact with the right Sun edge. At first, the black droplet appeared once again and then the Venus disappeared for good. That was at 13 hours 23 minutes and 4 seconds.
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| And what in the future? |
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Next transit will happen at 6th June 2012 and then in December 2117. Let us add that all times used are for Czech Republic. In other parts of the Earth, the contact times may differ by several minutes.
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;Prologue
