What’s the Biggest Star in the Universe

The age old question of does size matter really comes to life when thinking about it in terms of stars. When you’re wondering what the biggest star in the universe is, you have to understand how to envision its scale.

Our brains can’t even begin to conceive what this scale of size is like, largely because we don’t think in this scale or interact with objects of these sizes in our daily lives.

Imagine the biggest thing you interact with each day, probably the ground you walk on; meaning the Earth. It’s tough to even imagine the size of the Earth because we’re on it and only observing a small spec of it at any given time. But trying to compare a basketball to the size of a massive star is a waste of everyone’s time.

Introduction to Star Scaled Measurements:

The Earth’s circumference is 24,902 miles, meaning the distance around its equator at the surface level. That’s massive! The definition of a circumference of a circular object is the distance around the edge of a circular object.

The Earth’s radius (radius is the unit used to measure the size of stars) is 3,959 miles. The definition of a radius of a circular object is the distance from its center to any point on the edge of the object.

Now that you have a sense of how large the Earth’s radius is, you’re going to be amazed to find out how big our Sun’s radius is.

The Sun’s radius is 432,450 miles! It’s critical to note that this number represents what Astronomers refer to as a single “Solar Radius“. The solar radius is the measurement used to determine the size of other stars, which is used as a comparison point to our own star, the Sun.

Now take a look at the Earth and the Sun when compared to one another. Don’t miss the lower left corner, that’s the little rock you live on.



Photo by NASA Goddard Space Flight Center https://flic.kr/p/d6mHnY


So What’s the Biggest Star Out There?

Well, the Universe is so dang massive we’re still making our way through it to determine what the biggest star in the universe actually is. However, we’ve done a lot of searching and have a pretty good list of stars so big they’ll blow your mind.

Before we jump into the list of the biggest stars in the universe, check out this video to get a better visualization of the various size comparisons of objects throughout the Universe.



Now that you have a sense of how big various sizes of scale are throughout the Universe, let’s take a look and see what the biggest stars are in our Universe.


Name of Star

Solar Radius

Rank of Size

AH Scorpii



KY Cygni



VY Canis Majoris



VV Cephei A



VX Sagittarii



Westerlund 1-26






RW Cephei



NML Cygni



UY Scuti





“Comparison of planets and stars (sheet by sheet) (Apr 2015 update)” by Jcpag2012 – Own work. Licensed under CC BY-SA 4.0 via Wikimedia Commons – https://goo.gl/F1P3vP


The Biggest Star in the Universe is: UY Scuti:

We have a winner… so far. This could change with the discovery of a new star in some distant part of the Universe that we haven’t explored (via telescope) yet. UY Scuti is massive, in every form of that word. It’s radius is 1,708 times the size of our solar system’s Sun.

So Who is this UY Scuti you Speak About?

UY Scuti is a super awesome and bright red supergiant AND pulsating variable star, it’s so cool it’s included in 2 types of star characteristics. UY Scuti is located in the Constellation of Scutum, roughly 9,500 Light Years from our local solar system.

UY Scuti has a diameter of 1,500,000,000 miles, a radius of roughly 750,000,000 miles and a circumference of roughly 4,712,388,980 miles.

If we replaced our local Sun with this star, it would eat up Jupiter and might even swallow Saturn!

UY Scuti was first observed in 1860 by German Astronomers. If the conditions are just right, UY Scuti can be seen with a high quality set of binoculars, which is INSANE to think about. This massive star is 9,500 Light Years or equivalently 55,846,941,045,244,273.443092 Miles away and you can observe it with a set of nice binoculars your grandma gave you for your birthday!



“UY Scuti size comparison to the sun” by Philip Park – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – https://goo.gl/o0tj67


Something to Stick to the Roof of Your Mouth:

It’s truly amazing to think of how large these massive stars are compared to our local Sun. When you start to think of how far things are from your home or how far away your loved ones are; it’s nothing when compared to the distances, sizes and scales of objects in the universe.

If you were to travel at the speed of light, which is 669,600,000 miles per hour; it would take you over 7 hours and 2 minutes to fly around UY Scuti.

To put it into perspective, it would take a little more than 14.6 seconds to fly around the Sun’s surface traveling at the speed of light.

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  1. Claude Hubert

    I’m just a admirer of astronomy.. love to watch the night sky with binoculars,, ( too much city light to have a telescope..
    I love your Web page.. this is really the best for reference, it explain every thing in a way that I can understand..
    Keep it alive please…


    • Hey Claude,

      Thank you so much for your kind words, they mean a lot!

      Let us know if you ever have any specific questions or topics you’d like us to cover.

      Take Care and happy holidays!

  2. Chris

    It’s always wonderful to look up at the night sky and wonder about the things that I have read in your pages. Don’t stop doing such a marvelous job.

    • Thanks Chris, the Universe is an amazing and mysterious place. That’s one of the reasons I feel in love with astronomy and try to keep current with reading and posting what I learn. I hope you learned something and gained a little more appreciation for astronomy.

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