How Big Is the Biggest Star? The Answer Keeps Shrinking

For years, UY Scuti was listed as the biggest star in the universe: 1,708 times wider than the Sun. A few years later, the same star was listed at 909. Nothing happened to the star. It did not collapse or explode. One hidden number changed. That number is distance. Nobody can hold a ruler up to a star, so every star size depends on how far away the star is assumed to be. When the Gaia space telescope put UY Scuti much closer, it lost almost half its width on paper. The same problem hangs over every record holder, from Stephenson 2-18 to WOH G64, and the largest stars all seem to stop near the same ceiling of about 1,500 Suns. In this video: Earth, Jupiter and the Sun drawn to true scale, a passenger jet and a beam of light racing around the Sun, Betelgeuse and VY Canis Majoris placed where the Sun is, a star 140,000 times thinner than the air you breathe, how Gaia re-measured UY Scuti, the first close-up image of a star in another galaxy, and the Humphreys–Davidson limit. CHAPTERS 0:00 The star that shrank 1:06 From Earth to the Sun 2:35 The red supergiants 4:48 The number behind the number 6:40 So which star is the biggest? 9:27 Back to our Sun Absurd Scale explains the most extreme objects in the universe, drawn to real scale. Subscribe for the next one. #Space #Astronomy #BiggestStar