Venus Transit Finished

KjetilK writes "Venus is just about to cross the solar disc. Direct from the control room in the Frogner Park in Oslo, I'm pleased to inform you that we have a great webcast, and as far as we know, it is the only webcast that still stands upright... Slashdotters, do your worst! ;-) A Venus transit is one of the most unique astronomical events in our time, in fact, no living person has witnessed it before today. And today, more people have seen it from the park where I'm sitting that in the rest of human history. Also, it had tremendous importance for the development of science, as it gave the first absolute measurements of distances in the solar system. Especially in 1769, a transit made science take huge leaps forward. And BTW, New Zealand and Australia were 'discovered' in the process" Some nice photos from the UK, photos from vt-2004.org, and if you missed it, it'll be eight short years till you can try again.

Comments

Another article

[Mz6]

For those insterested, the poster really didn't leave any links to explain some of his claims about distances and the discovery of NZ and Australia.. This article I found explains most of it in detail.

Snippet:

How transits can determine distances:

In 1716, Edmond Halley was the first astronomer to suggest transits could be used to work out how far away the Sun is - also known as AU. Once this was known, the distances to all the other planets in the Solar System could be calculated.

If the transit was measured from several different places on earth, Halley reasoned, there should be a slight difference in the visible track across the sun. But this shift is so slight it is difficult to measure directly. Instead, the time at four different points during the transit can be noted down. These are: the first moment when Venus touches the Sun's disc, the moment when it is completely inside the disk, the moment when it makes contact with the other side of the disk on its way out, and the last moment of contact.

Astronomers can then compare these four timings as seen from different locations, a known distance apart. Using some fairly simple geometry the distance between the Earth and the Sun can be calculated.