Alvan Graham Clark, an American astronomer and telescope maker, discovered Sirius B, the companion star to Sirius, using an 18.5-inch (47 cm) refracting telescope. Positioned at Northwestern University, this telescope was one of the largest of its kind in its time, and Clark's expertise in lens crafting played a crucial role in this landmark achievement. The discovery of Sirius B was significant because it was the first time a white dwarf was identified, providing evidence for theories about stellar evolution and the life cycle of stars. Sirius, often referred to as the Dog Star, is the brightest star in the night sky, part of the constellation Canis Major. Its binary companion, Sirius B, is much dimmer and was not seen easily without advanced telescopes. The successful observation came after Clark meticulously fine-tuned the telescope for optimal clarity and sensitivity, enabling him to glimpse this faint star that eluded others. The techniques and technology developed during this process laid groundwork for future discoveries in astronomy, reshaping our understanding of star classifications and their various lifecycles.