Universe Guide

UY Scuti, Largest Star in the Milky Way Galaxy Facts

UY Scuti Facts

  • UY Scuti is a supergiant star that can be located in the constellation of Scutum. The description is based on the spectral class.
  • UY Scuti is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (M4Ia-Iab) of the star, the star's colour is red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • UY Scuti has a radius that is 1,708.00 times bigger than the Suns. Radius
  • The star is calculated at being about 5070.16 light years away from us. Distance

Information on UY Scuti

UY Scuti is one of the largest giant stars in the milky way and possibly the known and unknown Universe. The unknown universe being the part of the universe that we can't see or know about because it is so far away. It is not as some might think, in our Solar System, it is the centre of its own Solar System. In fact, UY Scuti is located close to the supermassive black hole  Sagittarius A*, the centre of our galaxy a.k.a. Galactic Centre. However as we are unable to measure all the stars, we will not know if that is the case that it is the largest in Universe. To put it in context, if the centre of UY Scuti was where our Sun was, the star's radius would extend out to Jupiter or even as far as Saturn. Other super large stars that could compete for the title of the largest in the galaxy include NML Cygni and VY Canis Majoris. UY Scuti is marginally in the grand sphere of things bigger than NML Cygni and both if placed in our solar system, would stretch out further than the orbit of Jupiter. To put it another way, it is 1.708 times the Sun's radius with a variance of about +/i 192.ref:Aanda.

The star is pronounced as U Y Scuti or U Y Scoo-ti. UY are pronounced as individual letters rather than as a separate word.

The age of UY Scuti has not been calculated but it could be as young as few million years or as old as a few billion. In other words, we are uncertain to the age of the star. No ones lived as long as a star so no one knows for certain a stars age, its only a best guess estimation.

UY is a semi-regular variable star in that it expands and contracts on an irregular base. Other large stars such as NML Cygni and VY Canis Majoris are also variable stars and as such they grow larger than UY Scuti and then retract to a small size. UY Scuti roughly pulsates about every 740 days. The figure given for its radius is the mean size. ref:wiki Due to its size, it is not going to live as long as Alpha Centauri which the later is a smaller star but burns through its energy at a slower pace. It is currently fusing main helium, of what is left of its hydrogen reserves are small contained in its core. It will one day go supernova or more appropriately to say hypernova.

The location is an estimated location for the star but it gives you an idea where in the constellation's boundary that the star can be located. Even though the star is very large, it is faint in the night sky and you will not be able to see it unaided without the help of a pair of binoculars or telescope. UY Scuti was only discovered in 1860 by German astronomers at Bonn University during a night survey. Although, there is a star within the circle, I'm not saying it is UY SCUTI.

It has passed the Main Sequence stage of its life, that is when hydrogen is fused into helium. It is now converting helium into Carbon and Oxygen. As it has past the main sequence, it is growing because of the outward pressure exceeds the inward pressure of gravity.

It will go supernova one day but even though it is a large star, it will not go supernova in the next million years because it has to work through the elements in its core until it gets to Iron. After Iron, it will not be able to continue to fuse elements any further. It is expected to heat up and become a yellow hypergiant star and also most likely shrink as it is become a hypergiant. When it goes Supernova or even Hypernova, we'll be too far away for it to have any direct effect on our planet and whatever life is on the planet will be unaffected. Long before UY Scuti goes supernova, Betelgeuse will have gone supernova and its a smaller star. UY Scuti will either become a Neutron Star or a black hole. It is not a Black Hole now, just a very very large star nearing the end of its life.

UY Scuti might well be tiny compared to the largest star in the universe but as there are so many stars not just in this galaxy but others means we don't know and will never know if UY Scuti is the largest in the Universe. The largest star could be in the Andromeda Galaxy for example or even in IC1101, the currently recognised largest galaxy so far discovered in the galaxy, we just don't know.

UY Scuti's Size

If you're struggling to put UY Scuti's size into context, try this. If the Earth was 20cm, the Sun would be 22 meters across and UY Scuti would be 40 km. To give you another idea of how big it is, it would take a plane travelling at the speed of light, 14.5 seconds to travel round the Sun, it would take seven hours for the same object to travel round UY Scuti. Wiki (French)

You would be able to fit around 6,520,000,000,000,000 or six quadrillion, five hundred twenty trillion Earths into the same space that UY Scuti inhabits. The Quora page that gives the calculation gives two amounts which two different people have calculated but you get the idea, its enormous.

If the amount of Earths that can fit into UY Scuti is a bit too high to comprehend, maybe the number of Suns that can fit into UY Scuti could be easier to understand. The number of Suns that can fit into UY Scuti is 5.1 Billion. Quora

You might think that because the star is a massive star, its temperature would match its size. The actual truth is far from that, UY Scuti's temperature is about 3,000 kelvin based on the Hertzsprung-Russell diagram. Size does not normally equate to temperature, its the colour that dictates the temperature. The more blue, the less red it is, the hotter the temperature is. The Sun is both hotter and smaller than UY Scuti.

Extrasolar Planets in Orbit

There is at yet no Extrasolar Planet (Exoplanet) discovered in orbit round the planet although possible, is probably most unlikely. A planet would be tiny compared to the star and detecting a planet from a wobble would be an immense challenge. When a planet orbits a star, it causes the planet to wobble but a planet would have to be extremely large for it to cause the star to wobble. Another method to detect planets would be if a planet transited in front of the planet. Again, a planet would have to be large to be seen transiting the planet. At present, its regarded as planetless.

UY Scuti's Alternative Names

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-12 5055.

More details on objects' alternative names can be found at Star Names .

Location of UY Scuti

The location of the supergiant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For UY Scuti, the location is 18h 27m 36.5334 and -12 ° 27` 58.866 .

Radial Velocity and Proper Motion of UY Scuti

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -1.60 ± 1.60 milliarcseconds/year towards the north and 1.30 ± 1.70 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 18.33000 km/s with an error of about 0.82 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of UY Scuti

UY Scuti Colour and Temperature

Based on the star's spectral type of M4Ia-Iab , UY Scuti's colour and type is red supergiant star. Based on the star's spectral, the stars temperature is between 2,400.00 and 3,700.00 degrees kelvin.

UY Scuti Radius

UY Scuti Radius has been calculated as being 1,708.00 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,188,426,400.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.

UY Scuti Mass

The UY Scuti's solar mass is 7.00 to 10.00 times that of our star, the Sun. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

UY Scuti Apparent and Absolute Magnitudes

UY Scuti has an apparent magnitude of 11.20 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 0.24 Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to UY Scuti

The Parallax of the star is given as 0.64330 which gives a calculated distance to UY Scuti of 5070.16 light years from the Earth or 1554.48 parsecs. It is about 29,805,571,222,100,612 miles from Earth.

The star is roughly 320,632,281.82 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Travel Time to UY Scuti

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A3807364,619,746,749.58
Speed of Sound (Mach 1)767.2694,431,475,281.41
Concorde (Mach 2)1,534.542,215,734,752.88
New Horizons Probe33,000103,034,351.75
Speed of Light670,616,629.005,070.16

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Additional UY Scuti Facts and Figures

Visual Facts

Primary / Proper / Traditional NameUY Scuti
Alternative NamesBD-12 5055
Spectral TypeM4Ia-Iab
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
GalaxyMilky Way
Visual / Apparent Magnitude11.20
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)18h 27m 36.5334
Declination (Dec.)-12 ° 27` 58.866
Distance from Earth0.64330 Parallax (milliarcseconds)
 5070.16 Light Years
 1554.48 Parsecs
 320,632,281.82 Astronomical Units
Proper Motion Dec.-1.60000 ± 1.60000 milliarcseconds/year
Proper Motion RA.1.30000 ± 1.70000 milliarcseconds/year
Radial Velocity18.33000 ± 0.82 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)1,708.00 (1,516.00 - 1,900.00)
Calculated Temperature Range2,400.00 - 3,700.00
Mass Compared to the Sun7.00 - 10.00

Location of UY Scuti in Scutum

UY Scuti Location in Scutum

The map was generated using Night Vision, an awesome free application by Brian Simpson.

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Comments and Questions

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ParimalTuesday, 5th April 2016 5:03:44 PM
Thanks it helped and I would appreciate if you try to put more pics of it and how to locate it in night sky plz it would be super helpful
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