Largest Star In the Universe - UY Scuti

Largest Star In The Universe? Facts About UY Scuti

So you found yourself pondering, what is the largest star in the universe? Well get ready, because we are about to reveal what the largest star in the universe is, and give you all the juicy facts about this behemoth of a star.

So what is the largest star in the known universe? The answer is UY Scuti. This star is over 1,700 times the radius of our own sun, yet only weighs 30 times our sun’s mass. UY Scuti is classified as a red supergiant and is referred to as a pulsating variable star – a star whose light fluctuates when viewed from Earth.

This hypergiant star, with an estimated radius larger than the orbit of Jupiter, stands out in the night sky as one of the most massive stars. Its fundamental properties and atmospheric structure, explored through techniques like VLTi AMBER spectro interferometry, have intrigued scientists, contributing valuable insights to astronomy and astrophysics.

UY Scuti’s physical size, larger than many stars in the Milky Way, emphasizes its significance in the study of the universe’s largest objects. The star’s estimated radius, when compared to other big stars like Vy Canis Majoris, showcases the incredible diversity of stellar radii within our galaxy.

Image of UY Scuti which is a hypergiant star.

How Big is UY Scuti?

It’s difficult to say just how big the largest star in the universe is due to its distance. It is believed that it is approximately 7 AU (Astronomical Units) in diameter or a radius of 3.5 AU. One AU is the distance from the Earth to our Sun, or approximately 150 million kilometers or 93 million miles.

So to put that into perspective, if we were to drop UY Scuti directly in the middle of our solar system where our sun currently resides, guess what??? The Mercury, Venus and Earth would be no more. In fact, UY Scuti would swallow up Mars, Jupiter and most likely Saturn…it is that immense!

This YouTube video below does a pretty good job putting a list of the biggest stars from our own sun right up through to the largest star in the universe, UY Scuti.

How Heavy is UY Scuti?

The precise mass of UY Scuti is challenging to determine accurately due to the limitations of observational techniques. Estimates suggest that UY Scuti is a massive star, likely in the range of 7 to 10 times the mass of our Sun.

UY Scuti is classified as a red supergiant, and its immense size and luminosity are characteristic of stars in advanced stages of their life cycle. While the exact mass remains uncertain, it is undoubtedly one of the heaviest stars known to astronomers.

Ongoing research and advancements in astronomical technology may provide more accurate measurements in the future, further enhancing our understanding of this colossal celestial object.

How Far Away is UY Scuti?

UY Scuti is located a whopping 9,500 light years away! This means, if you were traveling at the speed of light (299,792,458 m/s or approximately 300,000 km/s or approximately 186,000 mi/s) it would take you 9,500 years to get there. That’s an incredible distance.

Is UY Scuti Visible from Earth?

UY Scuti, despite being one of the largest known stars, remains elusive to the naked eye from Earth. The dimness inherent to UY Scuti further complicates its direct observation without the aid of telescopes or other astronomical instruments.

For amateur astronomers or sky enthusiasts keen on glimpsing UY Scuti, it is crucial to refer to astronomical charts and utilize telescopes equipped with suitable filters and magnification to enhance visibility. Keep in mind that factors like atmospheric conditions and light pollution can also influence the star’s visibility, making careful planning essential for a successful observation.

Power Tip!

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When was UY Scuti Discovered?

Image of an astronomer peering into the night sky with the milky way galaxy in the background.

UY Scuti was discovered back in 1860 by German astronomers at the Bonn Observatory. At that time, advancements in telescopic technology allowed astronomers to explore and catalog celestial objects with increasing precision. The discovery of UY Scuti, nestled in the constellation Scutum, was a notable milestone in the 19th-century efforts to map and understand the vastness of our night sky.

This red supergiant star, with its immense size and unique characteristics, became a subject of interest and scrutiny for astronomers seeking to classify and comprehend the diverse array of stellar objects in the universe. The observations made in 1860 set the stage for subsequent studies and paved the way for the inclusion of UY Scuti in the broader context of astronomical research.

Over the years, as technological advancements continued to improve our ability to study distant celestial bodies, astronomers have gained deeper insights into the fundamental properties and behaviors of UY Scuti.

Its discovery more than a century ago represents a foundational piece in the puzzle of understanding the cosmos and continues to contribute to our knowledge of stellar evolution and the extreme conditions within the universe.

When it was discovered is was cataloged BD-12 5055, the 5,055th star between 12°-13° South.

Where is UY Scuti Located?

It is located in the constellation Scutum. Its massive size, often compared to the solar system’s dimensions, makes it a red hypergiant and a subject of fascination for astronomers studying massive star formation.

To find the largest star in the universe you’ll need to aim your telescope towards the Eagle Nebula. This nebula is often referred to as the “Pillars of Creation” or “The Hand of God”. You can see from the image below why it gets this name. It is thought that stars are born here.

Image of massive star formation, and other stars in the Eagle Nebula.


The Eagle Nebula is easily visible through a good pair of binoculars, or a low-powered telescope. That said, UY Scuti, while extremely luminous, is only a 9th magnitude star when viewed from Earth. Wait a minute, what do I mean by magnitude?

A star or stellar magnitude refers to the apparent brightness of the celestial object when viewed from Earth. This means, the farther the star or object is from Earth, the higher its apparent magnitude will be (higher number means not as bright). Of course, this doesn’t diminish the actual brightness, or, luminosity, of the star or object. It just means it doesn’t appear as bright from Earth…phew…okay, I’m glad we cleared that up!

Locating the red hypergiant UY Scuti in below the tail of Aquilla

While UY Scuti is the largest star in the universe and it’s incredibly luminous, it doesn’t appear that way from Earth due to its shear distance (9,500 light years away). So with a low-mid powered telescope, such as the NexStar 4SE on Amazon, UY Scuti is located about 2° north of 5th-magnitude Gamma (γ) Scuti and 4° southwest of 4th-magnitude Alpha (α) Scuti just below the tail of Aquila.

Are there Planets Orbiting UY Scuti?

There is no confirmed planets orbiting UY Scuti. However, it’s important to note that the discovery of exoplanets and detailed studies of distant star systems are continually evolving fields in astronomy.

If there were planets could they sustain life?

This is a tricky question to answer, and of course we don’t know for sure. However, to answer this question we would need to look at the region about UY Scuti, known as the Goldilocks Zone. This is the region around a star that is that to be habitable because the temperature is just right – not too hot and not too cold.

While it is only an estimate, it is thought the Goldilocks Zone for UY Scuti is between 700 to 1300 AU. That’s an extremely large distance, roughly 150 billion kilometers if we took the average of these two numbers. That means it would take the light of UY Scuti approximately 40 days to reach a planet in the habitable zone.

While it’s not impossible to consider planets orbiting this zone around UY Scuti, the likelihood that they are sustaining life is minimal. Currently, UY Scuti is fusing helium at its core, meaning it has since exhausted hydrogen – we know this because it is a red supergiant. At this stage of a stars fusion process the star is heading towards its inevitable demise.

Once it exhausts its helium energy it will move on to consume higher level elements such as carbon, oxygen, lithium, neon, and silicon. It will consume these elements quite rapidly, a million years or so (not long in astronomical terms).

Once it exhausts all these elements it will begin to produce iron, and it will eventually collapse on itself. When a star collapses it is referred to as going Supernova. When a star goes supernova it is one of the most destructive acts of nature. The energy and explosive force that is released is unparalleled. It will be quite a fireworks show!

Exploring UY Scuti’s Orbital Neighbors

Image showing supermassive stars and other stars with an exoplanet.

While the focus on UY Scuti often centers on its colossal size, astronomers also cast their gaze beyond the star itself in the pursuit of potential exoplanets. This subheading delves into the ongoing exploration of UY Scuti’s orbital neighborhood, aiming to uncover any celestial companions that may orbit this massive star.

The quest for exoplanets around UY Scuti involves meticulous observations and analyses, with astronomers utilizing advanced technologies to detect any subtle signs of planetary presence. As our understanding of distant star systems evolves, the search for exoplanets around UY Scuti adds an exciting dimension to the broader field of exoplanetary science.

This exploration goes beyond the largest known star, delving into the mysteries of its potential planetary companions and contributing to the ever-growing catalog of exoplanets discovered in our vast universe.

Ongoing Studies Involving UY Scuti

The intrigue surrounding UY Scuti persists. Current studies are focused on delving deeper into the fundamental properties and atmospheric structure of this colossal star. Researchers employ advanced techniques, including VLTi AMBER Spectro Interferometry, to extract valuable insights that contribute to our understanding of massive stars and their evolution.

As the scientific community continues to explore the depths of UY Scuti, the potential for groundbreaking discoveries remains high. Future prospects include refining measurements, uncovering new details, and expanding our knowledge of the extremes that exist within the universe.

The ongoing investigation of UY Scuti stands as a testament to humanity’s relentless curiosity and the ever-evolving nature of astronomical exploration.


In the tapestry of astronomical exploration, UY Scuti emerges not only as the largest known star in the universe but also as a symbol of our relentless quest to comprehend the cosmos. As we peer into the night sky, UY Scuti beckons us to ponder the enormity of space, the diversity of celestial bodies, and the infinite possibilities that await discovery.