The famous American astronomer Brian Marsden said that for an ordinary person, the Solar System consists of three objects: planet Mars, the rings of Saturn, and Halley's Comet.
Edmond Halley studied and taught at Oxford, was the Director of the Royal Observatory at Greenwich, Newton’s friends, and the first publisher of Newton’s works. It was Newton who advised Halley to research comets. And he did. While before his time, people, depending on how educated they were, believed comets to be God’s wrath or wanderers in the Universe, Halley was the first to have calculated the orbits of 24 comets and noticed similarities in parameters of several heavenly wanderers observed in previous centuries. He predicted that a comet would appear in 1758-59. But he did not live to see his brilliant forecast confirmed. Apart from the comet named after him, Edmond Halley did a lot of other useful things, e.g., and devised an ingenious method to estimate the acreage of English counties. He did not measure or calculate it – there were no formulas to calculate the surface area of a shape at his time. He simply weighted them – not the counties themselves, of course, but their images cut out of maps. Then he compared the cutouts to the weight of the full map of England – its acreage was known.