These transits - the view of the planet Venus crossing the face of Sun - happen more than a century apart, with pairs of transits separated by eight years; the last was in 2004, and the current one happens on 5th-6th June. There are at least two good websites: see transitofvenus.org and transitofvenus.nl. The latter, the Dutch one, is particularly informative.
A few mildly relevant links: Mercury Transits The Sun, a cool scene from the movie Sunshine (which I mentioned in the 2009 post To the Sun); and Mr Meeson's Will, another previous post concerning the 1888 Rider Haggard novel, part of whose action involves a shipwreck on Kerguelen Island and refers to the expedition to observe the 1874 transit of Venus.
"What is Kerguelen Island?" asked Augusta.And then there's Jacob Abbott's 1852 didactic novel Cousin Lucy Among The Mountains (Internet Archive cousinlucyamong00abbogoog), in which the lead character goes trekking while being lectured on natural phenomena including astronomy:
"Oh! it is a desert place where nobody goes, except now and then a whaler to fill up with water. I believe that the astronomers sent an expedition there a few years ago, to observe the transit of Venus : but it was a failure because the weather was so misty — it is nearly always misty there. Well, I must be off, Miss Smithers. Good night ; or, rather, good morning.
Their first care was to go up to the huts and examine them, with a result that could scarcely be called encouraging. The huts had been built some years — whether by the expedition which, in 1874, came thither to observe the transit of Venus, or by former parties of shipwrecked mariners, they never discovered — and were now in a state of ruin. Mosses and lichens grew plentifully upon the beams, and even on the floor ; while great holes in the roof let in the wet, which lay in little slimy puddles beneath.
- Mr. Meeson's will (H Rider Haggard, 1888, Internet Archive mrmeesonswill00hagguoft),
"Sometimes it happens," said her mother, that, while Venus, after having been behind the sun, is passing round this side of it to go before it, that it goes exactly between us and the sun, and so we can see it pass across his face."I must check out Jacob Abbott - he was seriously prolific.
" How does it look ? " said Lucy.
"It looks like a little black spot," said her mother — "a little, round, black spot, moving across the face of the sun."
"What makes it look so black?" said Lucy.
"Why, it is only the side which is turned towards the sun tliat is bright, and the part that is turned towards us, when it passes between us^and the sun, will, of course, be dark. Besides,'' she continued, " I suppose that, strictly speaking, we don't really see Venus in that case at all. We are only prevented from seeing a part of the sun. Venus stops all the rays from that part of the sun which is exactly opposite to her, from coming to us ; and it causes the appearance of a small, round, dark spot, moving along over the face of the sun. That is called a transit of Venus. But a transit of Venus happens very seldom,"
"I should think it would happen every time Venus comes round," said Robert.
"So should I," said Lucy.
"No," said her mother.
"Because, you see," said Lucy, "that she must go by the sun every time."
"Yes," said her mother ; " that is true. But then sometimes she goes above the sun, and sometimes below it. It is very seldom that she goes across, exactly opposite to him; and it is only then that there is a transit."