The largest known star in the universe is UY Scuti. It is a red supergiant located in the constellation Scutum, approximately 9,500 light-years away from Earth. UY Scuti is considered one of the largest stars ever discovered, although its exact size is still uncertain due to the challenges of accurately measuring distant celestial objects.
To provide some perspective, UY Scuti has a radius estimated to be around 1,700 times that of the Sun, making it approximately 2.4 billion kilometers (1.5 billion miles) wide. If UY Scuti were placed at the center of our solar system, it would extend beyond the orbit of Jupiter.
This massive star has a relatively low surface temperature of about 3,500 degrees Celsius (6,332 degrees Fahrenheit), which gives it a reddish hue. Its luminosity, however, is exceptionally high, estimated to be around 340,000 times that of the Sun. Despite its tremendous size and brightness, UY Scuti is quite far from Earth, making it challenging to study in detail.
It's important to note that our understanding of the universe is continually evolving, and new discoveries could potentially reveal even larger stars in the future.