How big is our Sun compared to the largest known star in the Universe? We’re currently working on the latest version of our Star Size Comparison, taking the visuals to a whole new level. Here’s a sneak peek comparing our Sun to Stephenson 2-18 — the largest known star. You’ll also see how their temperatures affect the color of each star. The color of a star is determined by its surface temperature, with hotter stars emitting more blue and ultraviolet light, and cooler stars emitting more red and