It was shortly after this appointment that Halley would make his mark on history for good, though we cannot talk of Halley's comet without involving the mercurial Isaac Newton, whose work would become intertwined with Halley's own.
In 1684, Halley was discussing the problem with noted physicist Robert Hooke and the architect Christopher Wren in a London coffeehouse. Stymied, Halley paid a visit to Isaac Newton to discuss the matter with him. It was at this meeting that Newton revealed that he had already worked out a solution a few years before for another comet, but had set the matter aside.
He would be long dead by then, he knew, but using Newton's laws of motion, he was able to calculate the orbit of the comet with incredible precision and staked his reputation on his – and by extension, Newton's – figures. The problem was that no one had any idea how big the sun actually was. If the sun were the size of the moon, Earth could be orbiting at a distance of just 238,900 miles, while Jupiter, Mars, Venus, and Mercury could be much smaller and much nearer, relatively speaking.know how large the Earth was.