On October 5, 1644 (or according to the old julian calendar September 25), Danish astronomer Ole Christensen Rømer was born. He is best known for making the first quantitative measurements of the speed of light.
On October 2, 1608, German-Dutch lensmaker Hans Lippershey applied to the States-General of the Netherlands on October 2, 1608, for a patent for his instrument "for seeing things far away as if they were nearby".
On March 28, 1749, French mathematician and astronomer Pierre Simon marquis de Laplace was born, whose work was pivotal to the development of mathematical astronomy and statistics. One of his major achievements was the conclusion of the five-volume Mécanique Céleste (Celestial Mechanics) which translated the geometric study of classical mechanics to one based on calculus, opening up a broader range of problems.