394 years ago, famous astronomer Johannes Kepler discovered the 3rd and also last of his planetary laws, and concluded the general revolution of our celestial world that started with Nikolaus Kopernikus about 100 years earlier. And that made him rather popular as he still is today. Did you know that there is a Kepler crater on the Moon, a Kepler crater on Mars, a Kepler asteroid, a Kepler supernova, of course there has to be a space mission named after him, even an opera
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 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.
D. McComas, F. Allegrini, L. Bartolone, und et al.. Solar Wind 11/SOHO 16, Connecting Sun and Heliosphere, Volume 592 von ESA Special Publication, (September 2005)
J. Scheer, K. Bruning, T. Frohlich, P. Wurz, und W. Heiland. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 157 (1-4):
208--213(August 1999)