The Kant-Laplace hypothesis, IIRC, is the view that our solar system was at one point a vast disc-shaped cloud of dust, and that it gradually condensed into the several orbiting planets and the central star with which we are familiar.
The theory appears in "The Universal Natural History and Theory of the Heavens," pictured here, a pamphlet published in 1755. Here's the full text in English: http://records.viu.ca/~johnstoi/kant/kant2e.htm
Kant is of course better known for his Critical Philosophy, the great critiques that redefined epistemology, ethics, and aesthetics. He didn't even begin producing those great works until more than 20 years after he wrote the above pamphlet.
Kant, in a well known moment of self praise, said that he was producing philosophy's analog to the Copernican revolution. The praise has been much ridiculed, and I admit to my mind it seems perverse, since Kant's philosophy might at least as plausibly be seen as anti-Copernican, as a way of putting humans back at the center of the universe, from which point Copernicus had dislodged us.
Still, I find a good deal of wonderment in the fact that this Copernicus analogy comes from an intellectual descendant of Copernicus, a speculative astronomer of considerable significance in that field.
"Rudolph the Red knows rain, dear!"
And Kant knew his astronomy.
I expect to say something more about this hypothesis and its philosophical significance tomorrow.