In 1834, Friedrich Bessel discovered that Sirius periodically deviates from its position, which could only mean one thing: the star is accompanied by an invisible companion. However, the telescopes of that time were not able to detect it. The big event occurred three decades later, in 1862, when the American optician Alvan G. Clark, an excellent telescope designer, discovered a faint star near Sirius while testing his new 460 mm refractor, later designated as Sirius B - also known as the "Pup" in Anglo-Saxon regions. However, it was not until 1915 that its true physical nature was determined, making it the first ever discovered white dwarf.