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What are the Biggest Stars in the Universe?



Since the first men were born they have been looking up at the sky and naming stars. And though we now know that stars are actually entire balls of gas which have nuclear explosions on their surface due to nuclear fusions between atomic nuclei, the romanticism attached with stars has never gone away.

What has changed is the catalogue of stars that we have today and the number of stars that we know of in the universe. We now know of some of the biggest stars in the universe and how much they weigh compared to our sun.

This is made possible by the huge Hubble Telescope as well as the other large telescopes on earth and floating around in space that are capturing information from all corners of the sky. Massive stars and other celestial objects are identified all the time, and the catalogueis updatedon a regular basis. The biggest stars weigh more than a hundred times our own sun.

It’s natural to think that the sun is one of the largest stars in the universe, but it only appears that way since it’s the star that’s the nearest to our planet. On a stellar level, the sun is quite an average star depending on the catalogue that we’ve collected over the period of many hundreds of years. The largeststar known to us is UY Scuti. Thisis a hypergiant that has a radius that’sabout 1700 times the size of the sun. However, it’s hardly alone in dwarfing the sun.

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The Largest Stars in the Universe

The masses of stars are measured in solar masses, which is just a unit that is derived from the mass of our own sun. It’s one in a long series of units that are designed to measure the literally astronomical objects in space. These include the light year and the parsec, which are both massive units of distance, the orbital period (derived from the time that it takes for the earth to go round the sun), and solar radius (the radius of the sun) etc.

UY Scuti

UY Scuti may have been named the largest star very recently, but it was first discovered in 1860 by German astronomers. The observations were made at the prestigious Bonn Observatory. It was first named BD-12 5055. When it was detected for the second time, astronomers noticed that it grew dimmer and brighter over the period of 740 days.It is nearly 9500 light years away from earth and is situated in the center of our galaxy, the Milky Way.

UY Scuti is a hypergiant which areextremely rare stars. They are bigger than giants and supergiants.High intensity stellar winds proceed to take away significant portions of their mass.

The estimates for all stellarobjects are just that, estimates. They are based on measurements taken from incredible distances since no instrument has been known to travel further than the Oort cloud other than the Voyager spacecraft which were not meant to stay in contact with Earth forever.

Most stars have diffuse edges, making it difficult to pinpoint the boundary between the gas and vacuum. Hence, there really is no clear dividing boundary between space and the star itself.

Hence, the boundary is placed where the photons leave the star, which called the photosphere. This is the surface of the star as far as astrophysics is concerned.

This also means that since UY Scuti is a variable star, it varies in radius as well as brightness. It has a margin of error of about 192 solar radii.


This measures at around 1504 to 1730 solar radii and is a red hypergiant situated within the Large Magellanic Cloud. It is also a variable star similar to UY Scuti. Its variable brightness has put the upper estimate of its radius at 3000 solar radii. The differences that arise can be due to galactic dust. This affects how bright the star appears to telescopes and hence shortens its radius.

RW Cephei

Through the name, you may be able to surmise that this star exists within the Cepheus constellation. This orange hypergiant has an approximate radius of 1535 solar radii.

Westerlund 1-26

This star measures at nearly 1530 to 2550 solar radii. If the upper bound of the measurement is believed to be correct, it would be large enough to engulf Saturn if placed where our Sun is. Its temperature does vary, however, there are no variances when it comes to its brightness.

KY Cygni

The radius of KY Cygni varies from 1420 to 2850 solar radiiand it’s a red supergiant which is in the Cygnus constellation. The upper bound of this measurement is considered to be an error due to observational discrepancies. The lower bound, however, is considered a more accurate measurement due to the consistency with other stars that lie in the same sample. This estimate also agrees with several current stellar evolution models.

VY Canis Majoris

This is the star that held the top spot for the longest time. It has a radius of nearly 1300 to 1540 solar radii and is a red hypergiant. The upper bounds of its measurement first lay in the 1800 to 2200 solar radii neighborhood. However, observations conducted at a later time have brought the size of the star down considerably. Despite this, there are still sources that claim that the VY Canis Majoris is the largest in the list. Stars will continue to be discovered around the universe and we will continue to have bigger and bigger stars discovered in the furthest reaches of the observable universe. The biggest stars tend to be giants which are swelling and are not safe for any planet to inhabit the vicinity of. This is due to the fact that their behavior is unpredictable and because they can explode at any moment.

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