The UY Scuti is the largest star in the universe and measures 738,347,904 miles in radius. That is 1,700 times bigger than the sun! This star is located over 9,500 light years away and is classified as a “hypergiant” (after giant and megagiant). German astronomers at the Bonn Observatory discovered the UY Scuti in 1860. Later, other observers thought it had changed in brightness, making it a new variable star and giving the star its name. In a very clear night sky with no light pollution, UY Scuti can be viewed using binoculars or a small telescope and is recognizable by its red color.
The WOH G64 is another hypergiant star and has a radius of 665,723,520 miles. It makes up part of the Large Magellanic Cloud galaxy and is over 168,000 light years from Earth. Westerlund, Olander, and Hedin discovered the WOH G64 in the 1970’s. The astronomer’s initials gave the star its name. This star also emits a reddish hue.
The third largest star in the galaxy is the RW Cephei. Its radius measures 663,562,080 miles and is part of the Cepheus constellation. In Greek mythology, Cepheus is a king who holds down the Pole Star, Polaris, with his foot. This star is another hypergiant, 1,500 times bigger than the sun, and reflects an orange color. It would take 11,500 light years to reach the RW Cephei.
Number 4 on the list is the 661,400,640-mile radius Westerlund 1-26 red supergiant star. This giant was discovered in 1961 by Bengt Westerlund. It is over 11,500 light years away and requires a high-powered telescope for viewing due to space dust obscuring it.
Next, on the list is located in the Milky Way galaxy. The V354 Cephei star takes 5th place as one of the largest stars and is 657,077,760 miles in radius. Like the RW Cephei, this star makes up the Cepheus constellation only it is considered a megagiant. The V354 shines 38,000 times brighter than the sun, but at 9,000 light years away, requires a telescope for viewing.
VY Canis Majoris
Slightly closer than the other stars listed so far, the VY Canis Majoris is located 4,000 light years away. This 613,848,960-mile radius star is part of the Canis Major constellation in the Milky Way. In 1801, a French astronomer discovered and recorded its existence. Scientists estimate that this star has already burned off half its mass which now hangs around it in a nebula cloud. Because of this, predictions estimate that the VY Canis Majoris will explode in the next 100,000 years.
The KY Cygni star is 611,687,520 miles in radius and was discovered using an 84-inch telescope located at the Kitt Peak National Observatory in Arizona, USA. This star is a red supergiant variable star and located 5,000 light years away. The KY Cygni is losing its mass at one of the fastest rates recorded for a red supergiant and is therefore considered “cool.”
At 609,958,368 miles in radius, the AH Scorpii is the 8th largest star known. This star is located in the Scorpius constellation which is one of the zodiacs and found in the middle of the Milky Way. The AH Scorpii is another red supergiant variable star. In ancient time, Libra and Scorpius constellations were believed to be one.
This star is a pulsating variable and is located about 1,076 light years away. The VX Sagittarii has an impressive 583,588,800-mile radius and gives off a red glow. It is considered a cool star because it burns somewhere between 2,500K and 3,500K in temperature. It is most well-known for being part of the Sagittarius constellation.
HR 5171 A
The final star on the list is the HR 5171 A. This massive star is 568,458,720 miles in diameter. While it is not the largest on the list, it is the largest yellow hypergiant star known to exist. This color is very rare, and there are only around 12 recorded. The HR 5171 A is about 12,000 light years away and has a large, extended atmosphere due to its rapidly changing environment. Astronomers discovered this star by using the interferometry technique which combines light from various telescopes.