What is a Supercluster?
From the words “super” and “cluster,” we get the idea that galaxy superclusters are large groups of galaxies. But how large are they?
Superclusters are believed to span up to 200,000,000 light-years across or more. They usually consist of around ten to a dozen galaxy clusters. Each of these galaxy clusters is a concentration of hundreds to thousands of galaxies that are bound together by gravity. With that said, they are some of the largest structures in the cosmos and are believed to most likely fill about 10% of the volume of the universe.
A great example of a supercluster is our Local Supercluster—also called the Virgo Supercluster. Our Milky Way Galaxy, along with more than 45,000 other galaxies, is part of this supercluster.
Below are other useful terms that we might come across as we learn about the different structures of the Universe.
- Galaxy: a collection of dust and gas with billions of stars and their planets
- Galaxy Group: a concentration that typically consists of less than 50 galaxies
- Galaxy Cluster: a concentration of galaxies larger than a galaxy group and is usually made up of around 50–1,000 galaxies or more
- Galaxy Supercluster: a large group of galaxy groups and galaxy clusters
- Galactic Sheets and Filaments: very large groups of galaxy superclusters and are the largest structures in the known Universe
- Galactic Voids: vast spaces in the Universe that contain very few or no galaxies
- Dark matter: an invisible and mysterious form of matter that seems to hold the Universe together
Supercluster: A Cosmic Network
The Sun is the most important object in the solar system. This yellow main-sequence star makes life possible on Earth. Plants need sunlight to grow and make food. In turn, humans and animals need plants for oxygen and food consumption.
Without the Sun’s heat, our planet would become too cold to make life possible. While the Sun is the most massive object in the solar system, it is only one of the 100 to 400 billion stars in our galaxy, the Milky Way.
A galaxy is a gravitationally bound system of gas, dust, and millions to billions of stars. This might seem a lot but there are other much larger structures in the Universe. Galaxies belong in galaxy groups—a collection of typically less than 50 galaxies that are bound by gravity. Our Milky Way belongs to the Local Group. The Milky Way and the Andromeda Galaxy are the most massive members of this group.
Groups & Clusters
Galaxy groups are part of larger structures called galaxy clusters. These are larger groups of galaxies with hundreds to a few thousands of galaxy members. The closest cluster of galaxies to Earth is the Virgo Cluster.
Galaxy clusters and galaxy groups form an even larger structure called a Supercluster. The Local Group, where the Milky Way belongs, is part of the Local Supercluster. Our Local Supercluster is also called the Virgo Supercluster because its largest member is the Virgo cluster of galaxies, which is also located near the heart of this colossal structure.
What is the Virgo Supercluster?
- Diameter: 110 million light-years (33 megaparsecs)
- Mass: 10 quintillion Suns
- Number of member galaxies: ~100 galaxy groups and galaxy clusters
- Constellation: Virgo the Maiden
- Parent structure: Laniakea Supercluster
The Virgo Supercluster is a great concentration of galaxy groups and clusters to which the Local Group, and of course the Milky Way, belongs. It is also called the Local Supercluster. This colossal structure is just one of the ~10 million superclusters that make up the observable universe.
Superclusters are very large so defining their exact boundaries is a challenge. Another thing to consider is that since we are inside it, we cannot have an overall “aerial view” of the whole thing. However, estimates show that the Virgo Supercluster spans around 110 million light-years. This is the diameter that you get if you were to place around 1,000 Milky Ways together, end to end.
There’s Big, And Then There’s BIG
Our cosmic megacity is not only tremendously large, but it is also very massive. According to Astronomy.com, the mass of our Local Supercluster equals the mass of around 10 quintillion solar masses. That is 10 with 18 zeros or 10,000,000,000,000,000,000 Suns!
The Virgo Supercluster, located in the constellation Virgo, was named after its largest member, the Virgo Cluster, which lies near its center. There are at least 100 galaxy groups and galaxy clusters that make up this supercluster.
Though our Local Supercluster is quintillions of times more massive than the Sun, much of its mass is not luminous. This is because this cosmic structure is mostly filled with the ever mysterious dark matter, just like everything in the Universe.
Clusters Within Clusters
The Virgo Supercluster is part the bigger Laniakea Supercluster. This larger structure is home to the Milky Way, the Magellanic Clouds, the Andromeda Galaxy, and about 100,000 galaxies nearby. It is estimated to span 520 million light-years and is approximately as massive as 100,000 Milky Ways.
The name “Laniakea” has a Hawaiian origin which means “immense heaven” or “open skies.” It was discovered in 2014 and is centered on the Great Attractor. The Virgo Supercluster has become a subpart of this larger structure with other three superclusters namely the Hydra–Centaurus Supercluster, the Pavo–Indus Supercluster, and the Southern Supercluster.
The Virgo Supercluster and the larger Laniakea Supercluster are part of a larger galaxy filament called the Pisces–Cetus Supercluster Complex. Galaxy filaments consist of superclusters and walls and are the largest structures known in the Universe.
The Local Group and our Neighbor Galaxies
The Milky Way and the Andromeda Galaxy (Messier 31) are the most massive members of the Local Group. Both of them are spiral galaxies, characterized by their swirling arms. The third-largest member is the Triangulum Galaxy (Messier 33) which is also a spiral.
The Local Group has a diameter of approximately 10 million light-years and has more than 30 galaxy members. Most of its mass is concentrated around the Milky Way and the Andromeda Galaxy. Smaller companions called “satellites” are associated and gravitationally bounded with these two galaxies. Most of these satellites are smaller or dwarf galaxies, but sometimes they can also be very massive.
The Large Magellanic Cloud and the Small Magellanic Cloud are the most famous satellite galaxies of the Milky Way. Meanwhile, the Andromeda Galaxy has been imaged several times with its two satellites Messier 32 and Messier 110. Other notable galaxies in the Local Group are the Canis Major Dwarf, Sagittarius Dwarf, Barnard’s Galaxy, and Ursa Minor Dwarf, among others.
Groups of Galaxies in the Virgo Supercluster
Maffei 1 Group
The Local Group is just one of many other galaxy groups in the Virgo Supercluster. The closest group of galaxies in the Local Group is called the Maffei 1 Group. It was thought to be a part of the Local Group in the distant past but was expelled after a violent encounter with the Andromeda Galaxy.
Discovered in 1968, the largest members of this group are the elliptical galaxy Maffei 1 and the spiral Maffei 2 which are 10 and 16 million light-years away, respectively.
At around 12.7 million light-years distant, another relatively close group of galaxies is the Sculptor Group. It is named after its most notable member, the Sculptor Galaxy (NGC 253), which is an intermediate spiral galaxy. The galaxies in this group are weakly gravitationally bound so others also consider this cosmic structure a filament.
The M81 Group is also part of the Virgo Supercluster. It is located in the boundaries of Camelopardalis and Ursa Major some 12 million light-years from us. There are 34 known member galaxies in this group. The two most prominent large galaxies in the group, M81 and M82, are gravitationally interacting with each other which results in star formation. The M81, which is the largest galaxy in this group, houses a supermassive black hole at the center 70 million times more massive than the Sun.
Centaurus A/M83 Group
Another group of galaxies that lies within the Virgo Supercluster is the Centaurus A/M83 Group. Centaurus A is the most notable member of the group and is the nearest radio galaxy to us. Another distinguishable galaxy is the M83 galaxy, also known as the Southern Pinwheel galaxy.
Canes Venatici I Group and Canes Venatici II Group
Canes Venatici I Group or M94 Group is a loosely bound group located in the constellations of Canes Venatici and Coma Berenices. Located behind Canes Venatici I is the Canes Venatici II Group. It is located roughly 26 million light-years away. The largest and most famous member is M106. This spiral galaxy has a notable water vapor megamaser emission.
Another loose group in Virgo Supercluster is the M101 Group. Its largest member is M101 or the famous Pinwheel Galaxy. It is located in the Ursa Major constellation. The other members of this group are mostly satellites of the Pinwheel galaxy.
Discovery of Virgo Supercluster
Our understanding of the greater scale of the Universe has evolved as science and technology improved. The concept of large cosmic structures like the Virgo Supercluster only existed around the 1950s.
Just like how it was thought that the Earth was the center of the Solar System, there was also a time when it was thought that the Milky Way was the only galaxy out there. Telescopes before were not as advanced as they are now. So when William Herschel and his son John Herschel used one to study the sky around the 18th and 19th centuries, they saw a lot of unusual objects that they called “nebulae.”
At that time, the word “nebulae” was used to call rather fuzzy celestial objects that were not comets. It was also thought that these nebulae all lie within the boundaries of the Milky Way galaxy.
The Great Debate
The historical Great Debate of 1920 helped establish the nature of these so-called nebulae. This debate was between two astronomers, Harlow Shapley and Heber Curtis. Each of them had their own view on what these objects are which are useful in understanding the true scale of the universe.
The then called Andromeda Nebula was one of the subjects of this event. Harlow Shapley argued that the Milky Way is the whole of the universe and the nebulae like Andromeda are within it. Heber Curtis, however, pointed out that these nebulae were “island universes” or separate galaxies from the Milky Way. Years after, through Cepheid variable stars, Edwin Hubble was able to prove Curtis’s claim that Andromeda is a separate galaxy.
After it was established that many other galaxies exist, astronomers were left to reinterpret their previous findings. Earlier in the 1860s, John Herschel noticed the large concentration of galaxies in the area around the Virgo constellation. It was only about a century later, in the 1950s, that another great observation on these objects followed.
Years after the great debate, it was already understood that the concentration of nebulae around Virgo is actually individual galaxies. Astronomer Gérard de Vaucouleurs observed that these galaxies seemed to be close to each other and are moving from us at the same rate. In 1953, he called this concentration the Local Supergalaxy and changed it to Local Supercluster in 1958.
Where is the Virgo Supercluster Located?
Everything is relative when we talk about locations in the Universe. So the best way to determine the location of the Virgo Supercluster in the observable universe is by starting with the Earth. Our home planet can be found deep within the complex system of the much larger Virgo Supercluster.
The Virgo Supercluster is made up of many galaxy groups and galaxy clusters. The most notable of which is the Virgo Cluster which is approximately 65 million light-years away, lying at the center of the Virgo Supercluster.
Using the diagram above, we start by looking at Earth, our planet, then the larger Solar system which is part of the Solar Interstellar Neighborhood or the stars around the Sun’s neighborhood in the Milky Way. Our galaxy, in turn, is part of the Local Group which is made up of other nearby galaxies.
Scales Of Magnitude
The Local Group of galaxies is part of the Virgo Cluster which is part of the Virgo Supercluster (Local Supercluster). It was found out that the Virgo Supercluster is just a part of the bigger Laniakea Supercluster of galaxies. The Laniakea Supercluster is part of the much bigger Pisces–Cetus Supercluster Complex.
Interestingly, it is estimated that there are about 10 million superclusters in the observable universe alone. The observable universe is the only part of the Universe that we have seen based on the oldest light that has reached us. However, the entire Universe is believed to be at least 250 times the size of the observable universe.
With all that said, we can only determine the location of the Virgo Supercluster based on the structures and systems that it is made up of. Since we are inside it and have never seen it from the outside, we cannot fully see how it fits in the much larger structure of the observable universe. Still, knowing about our location within these different structures is an important step in uncovering the truth about our local universe.
The Hydra-Centaurus Supercluster is the nearest neighbor to our very own Virgo Supercluster. The Centaurus Cluster (Abell 3526) and the Hydra Cluster (Abell 1060) are the two most notable clusters that make up this large cosmic structure. The Hydra-Centaurus Supercluster is now part of the larger Laniakea Supercluster, which the Virgo Supercluster is also a part of.
The Coma Supercluster, located around 300 million light-years from us, is another nearby supercluster. It consists of the Coma Cluster (Abell 1656) and the Leo Cluster (Abell 1367), among others.
The Perseus-Pisces Supercluster lies roughly 250 million light-years away from Earth. Its two most important clusters are Perseus Cluster (Abell 426), Abell 262, and Abell 347. This supercluster lies near the Taurus Void.
The Pavo-Indus Supercluster stretches around the constellations of Pavo, Indus, and Telescopium. It has a wall or filamentary structure that spans about 215 million light-years across. It is part of Laniakea Supercluster.
Interesting Facts About Superclusters and the Universe
- Do you want to know your complete cosmic address? Well, here it is: (country), (continent), Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster, Pisces–Cetus Supercluster Complex.
- The Sloan Great Wall and the Hercules–Corona Borealis Great Wall or simply, Great Wall, are the largest known cosmic structures. The Sloan Great Wall is believed to make up about 1/60 of the entire diameter of the observable universe. The Great Wall, on the other hand, has a diameter of 93 billion light-years.
- The Laniakea Supercluster is dissolving. This is not a new thing, however, since superclusters and other structures in the Universe are only apparent structures. They are not completely bound to each other because of dark energy. Because of the expansion of the Universe, they will eventually dissociate.
- Compared to the much bigger scale of the Universe, the entire human race would actually just fit in the size of a sugar cube. That is because 99.99% of ordinary matter, or the things that we are made up of, is empty space.
- We only know about 5% of the Universe. Most of it is invisible and made up of dark energy and dark matter. The word “dark” here does not have anything to do with their colors. They are called so because they are unknown and invisible forms of matter and energy, leaving us in the dark about their true nature.
What is a Supercluster?: https://upload.wikimedia.org/wikipedia/commons/4/46/Superclusters_atlasoftheuniverse.gif
What is the Virgo Supercluster?: https://www.universetoday.com/wp-content/uploads/2014/12/201103_VirgoGCM_andreo.jpg
The Local Group and our Neighbor Galaxies: https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Local_Group.svg/683px-Local_Group.svg.png
Maffei 1 and Maffei 2: https://upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Maffei_1_and_2.jpg/1024px-Maffei_1_and_2.jpg
Centaurus A: https://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/ESO_Centaurus_A_LABOCA.jpg/800px-ESO_Centaurus_A_LABOCA.jpg
M101 Group: https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/M101_hires_STScI-PRC2006-10a.jpg/1024px-M101_hires_STScI-PRC2006-10a.jpg
William Herschell: https://upload.wikimedia.org/wikipedia/commons/thumb/3/36/William_Herschel01.jpg/800px-William_Herschel01.jpg
John Herschel: https://upload.wikimedia.org/wikipedia/commons/6/62/John_Herschel_1846_%28cropped%29.png
Where is the Virgo Supercluster Located?: https://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/Earth%27s_Location_in_the_Universe_SMALLER_%28JPEG%29.jpg/1200px-Earth%27s_Location_in_the_Universe_SMALLER_%28JPEG%29.jpg?20160309032437