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Our Milky Way galaxy is the island of stars we call home. If you imagined it as a disk with spiral arms emanating from the center, our sun is about a third of the way from the center to the visible edge. Our solar system is located between two prominent spiral arms, in what astronomers once thought was a mere bridge of stars, gas, and dust clouds. In recent decades, research advances have revealed that we live in our very own spiral arm of the galaxy, albeit a relatively minor one. Our spiral arm is formally called the Orion-Cygnus Arm. It's also known simply as the Orion Arm or Local Arm, and you sometimes still hear the names Orion Bridge or Orion Spur.

Th Milky Way is a spiral galaxy. In fact, the Milky Way is a barred spiral galaxy, which means it has a central bar. There's still a lot we don't know about the structure of our galaxy. According to the best current knowledge, the Milky Way is about 150,000 to 200,000 light-years across, and about 2,000 light-years deep, and has 100 to 400 billion stars. There may be four primary spiral arms emanating from its center bar with an unknown number of smaller offshoot arms.

Where, within this vast spiral structure, do our sun and its planets reside? We're about 26,000 light-years from the center of the galaxy, on the inner edge of the Orion-Cygnus Arm.

It's sandwiched by two primary spiral arms, the Sagittarius and Perseus Arms. The artists' concepts above and below show the Orion-Cygnus Arm, the home spiral arm of our sun in the Milky Way galaxy.
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The Orion Arm of the Milky Way is thought to be some 3,500 light-years wide. Initially, astronomers thought it was about 10,000 light-years in length. A new study - published in 2016 - suggests it's more than 20,000 light-years long.

Astronomers are continuing to piece together the structure of the Milky Way by painstakingly measuring the positions and distances to many stars and gas clouds. Distances are determined from parallax measurements by telescopes on the ground and in space. One currently-operational space telescope, Gaia, is expected to provide a wealth of new information to better characterize the Milky Way's structure and size. In fact, it's Gaia's stated goal to provide a 3-dimensional map of our Milky Way.

The Orion Arm is named for the constellation Orion the Hunter, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of this constellation (Betelgeuse, Rigel, the stars of Orion's Belt, the Orion Nebula) are neighbors of sorts to our sun, located within the Orion Arm. That's why we see so many bright objects within the constellation Orion - because when we look at it, we're looking into our own local spiral arm.

Bottom line: The sun is about 1/3 the distance from the center of the Milky Way galaxy to its outer edges. It's located in a smaller spiral arm, between two large arms, called the Orion Arm.

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Which spiral arm of the Milky Way contains our sun? | EarthSky.org

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Our Milky Way galaxy is the island of stars we call home. If you imagined it as a disk with spiral arms emanating from the center, our sun is about a third of the way from the center to the visible edge.

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Detailed map of our place in the universe

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Detailed map of our place in the universe

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We know that the Earth and the solar system are located in the Milky Way galaxy. But how, exactly, does the Milky Way fit in among the billions of other galaxies in the known universe?

In a fascinating 2014 study for Nature, a team of scientists mapped thousands of galaxies in our immediate vicinity, and discovered that the Milky Way is part of a jaw-droppingly massive "supercluster" of galaxies that they named Laniakea.

This structure is much, much, much bigger than astronomers had previously realized. Laniakea contains more than 100,000 galaxies, stretches 500 million light years across, and looks something like this (the Milky Way is just a speck located on one of its fringes on the right):

Say hello to Laniakea, our local supercluster

It's hard to wrap one's head around how enormous this is. Each of those points of light is an individual galaxy. Each galaxy contains millions, billlions, or even trillions of stars. Oh, and this all is just our little local corner of an even broader universe. There are many other galaxy superclusters out there.

So how did the researchers figure out this structure existed - and how did they distinguish it from other superclusters?

The team of scientists, led by R. Brent Tully of the University of Hawaii, first studied the motion of some 8,000 galaxies in our neighborhood. By doing so, they could map out certain patterns. The universe overall has been expanding ever since the Big Bang. But the team also found that gravity was pulling some galaxies toward each other.

That helped them build the graph below, where galaxies moving away from us are shown in red, and the galaxies moving toward us in blue.

The galaxies around us are moving in identifiable patterns

That, in turn, let them create a map of the pathways along which all the galaxies are moving and demarcate some boundaries.

The map below shows some of the pathways within our broader supercluster of galaxies. There's an especially dense region called "The Great Attractor" (in red) that's slowly pulling the Milky Way and many other galaxies toward it:

Many galaxies in Laniakea are being pulled toward the "Great Attractor"

What's interesting is that this structure is much bigger than anyone had realized. Astronomers had long grouped the Milky Way, Andromeda, and other galaxies around us in the Virgo Supercluster, which contained some 100 galaxy groups.

But as Tully and his colleagues found, and as the map above shows, this Virgo Supercluster is just part of a much, much bigger supercluster - Laniakea. (The name, aptly enough, means "immeasurable heavens" in Hawaiian.)

So what happens when we zoom out? The paper notes that Laniakea borders another supercluster known as Perseus-Pisces. And the scientists defined the borders as where the galaxies are consistently diverging:

Laniakea borders another supercluster: Perseus-Pisces

What happens if we zoom out even further? Even Laniakea and Perseus-Pisces are just one small pocket of the much broader universe. That universe consists of both voids and densely packed superclusters of galaxies. It looks something like this:

And... zooming out to the broader universe

We still don't have detailed maps of every last galaxy supercluster out there. But we now have one for our own home supercluster - and that's certainly a start.

Further watching: There's an excellent video from Nature breaking down the team's findings. The stills above come from that video.

Further reading: Over at Slate, Phil Plait has a nice breakdown of the study, which was released in September 2014.

Why every picture of a black hole is an illustration

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This is the most detailed map yet of our place in the universe

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We know that the Earth and the solar system are located in the Milky Way galaxy. But how, exactly, does the Milky Way fit in among the billions of other galaxies in the known universe?

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Facts about Earth, including its location, size, rotation, physical features and more

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The Milky Way is just one galaxy located in a vast cluster of galaxies known as the Local Group. This group contains more than 50 galaxies (mostly dwarf galaxies). The total size of the Local Group is 10 million light-years across, and it's estimated to have a mass of 1.29 billion solar masses. The Local Group is just one collection of galaxies in the even bigger Virgo Supercluster.

The largest, most massive galaxies in the Local Group are the Milky Way, Andromeda and the Triangulum Galaxy.

Each of these galaxies has a collection of satellite galaxies surrounding them. For example, the Milky Way has Sagittarius Dwarf Galaxy, Large Magellanic Cloud, Small Magellanic Cloud, Canis Major Dwarf, Ursa Minor Dwarf, Draco Dwarf, Carina Dwarf, Sextans Dwarf, Sculptor Dwarf, Fornax Dwarf, Leo I, Leo II, and Ursa Major Dwarf.

Andromeda has satellite galaxies M32, M110, NGC 147, NGC 185, And I, And II, And III, And IV, And V, Pegasus dSph, Cassiopeia Dwarf, And VIII, And IX, and And X.

The Traingulum galaxy might be a satellite to Andromeda, and it might also have the Pisces Dwarf as a satellite.

The other members of the Local Group, not associated with another galaxy, include: IC10, IC1613, Phoenix Dwarf, Leo A, Tucana Dwarf, Cetus Dwarf, Pegasus Dwarf Irregular, Wolf-Lundmark-Melotte, Aquarius Dwarf, and Sagittarius Dwarf Irregular.

The first astronomer to identify the Local Group was Edwin Hubble, who called the collection the Local Group in his book, The Realm of Nebulae. Of course, at this time Hubble didn't know that they were distant galaxies, separate from our own Milky Way, so he called them nebulae.

We have written many articles about galaxies for Universe Today. Here's an article about a dwarf galaxy falling into the local group, and here's an article about how the Universe doesn't seem to be expanding evenly.

If you'd like more info on galaxies, check out Hubblesite's News Releases on Galaxies, and here's NASA's Science Page on Galaxies.

We have also recorded an episode of Astronomy Cast about galaxies - Episode 97: Galaxies.

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What is the Local Group? - Universe Today

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The Milky Way is just one galaxy located in a vast cluster of galaxies known as the Local Group. This group contains more than 50 galaxies (mostly dwarf galaxies). The total size of the Local Group is 10 million light-years across, and it's estimated to have a mass of 1.29 billion solar masses.

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If you're on a dark countryside hill some night, look up at the sky. Arcing overhead, a faint band of light may appear that looks like milk spilled across the sky. The ancient Romans called the band via lacteal, which means "milky road" or "milky way."

The band of light that you see isn't actually milk, of course-it's a galaxy. A galaxy is a huge bunch of stars clustered together in space. Our solar system-which includes the sun, Earth, and seven other planets-is part of this galaxy, called ... you guessed it ... the Milky Way.

The Milky Way contains hundreds of billions of stars like our sun. (And like our sun, most of these stars have at least one planet orbiting them.) Earth is located about halfway between the center of the Milky Way and its outer edge.

Light at the galaxy's center takes 25,000 light-years to travel from Earth. (A light-year is the distance light travels in one year.) So that means if you could see the core of the Milky Way, you'd be observing light that possibly left Earth before humans first settled in North America.

At the center of the Milky Way is one of the strangest and deadliest things in the universe: a black hole. Black holes are born when a giant star runs out of energy. The star implodes, causing an explosion called a supernova. The star's heart collapses under its own weight. It's squashed into a tiny dot you can't see.

Scientists suspect a black hole lurks at the center of most galaxies. The Milky Way's black hole is called Sagittarius A*. (A* is scientist-code for "A-star.") Its gravity, or attractive force, is so strong that it pulls in anything that gets too close, including stars. So we're lucky that Earth is located far away from the center!

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

Beyond Mars is the asteroid belt - a region populated by millions of rocky objects. These are left-overs from the formation of the planets, 4.5 billion years ago.

On the far side of the asteroid belt are the four gas giants - Jupiter, Saturn, Uranus and Neptune. These planets are much bigger than Earth, but very lightweight for their size. They are mostly made of hydrogen and helium.

Until recently, the furthest known planet was an icy world called Pluto. However, Pluto is dwarfed by Earth's Moon and many astronomers think it is too small to be called a true planet.

An object named Eris, which is at least as big as Pluto, was discovered very far from the Sun in 2005. More than 1,000 icy worlds such as Eris have been discovered beyond Pluto in recent years. These are called Kuiper Belt Objects. In 2006, the International Astronomical Union decided that Pluto and Eris must be classed as "dwarf planets".

Even further out are the comets of the Oort Cloud. These are so far away that they are invisible in even the largest telescopes. Every so often one of these comets is disturbed and heads towards the Sun. It then becomes visible in the night sky.

Last modified 07 August 2014

Related articles

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

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It's time to expand your mind and consider the largest structures in the Universe: vast collections of galaxies known as superclusters. There's really nothing bigger in the Universe. The supercluster we live in is known as the Virgo Supercluster. It's an enormous collection of more than a million galaxies, stretching across a region of space 110 million light-years across.

Our Sun is just one member of the Milky Way, and the Milky Way is part of a collection of galaxies known as the Local Group. This contains three large spiral galaxies: the Milky Way, Andromeda, and the Triangulum Galaxy, as well as a few dozen dwarf galaxies. The Local Group is just one member of the Virgo Cluster. This is a collection of 1200-2000 galaxies that stretch across 15 million light-years of space. And then, the Virgo Cluster is just one cluster in the Virgo Supercluster.

Although astronomers recognized that we were in a supercluster of galaxies in the 1950s, it wasn't until the 1970s that astronomers actually mapped out the Virgo Supercluster's shape; it has a flattened disk, somewhat like our galaxy itself. Our Virgo Cluster is actually an outlying group of the Virgo Supercluster.

The Virgo Supercluster is just one of millions of superclusters across the Universe. From the largest scales, they're arranged in long filaments and walls surrounding even large voids of space where there are almost no galaxies at all.

We have written many articles about galaxies for Universe Today. Here's an article about how the Universe isn't expanding uniformly.

If you'd like more info on galaxies, check out Hubblesite's News Releases on Galaxies, and here's NASA's Science Page on Galaxies.

We have also recorded an episode of Astronomy Cast about galaxies - Episode 97: Galaxies.

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caption] It's time to expand your mind and consider the largest structures in the Universe: vast collections of galaxies known as superclusters. There's really nothing bigger in the Universe. The supercluster we live in is known as the Virgo Supercluster. It's an enormous collection of more than a million galaxies, stretching across a region of ...

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What is a supercluster & the Virgo supercluster

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What is a supercluster & the Virgo supercluster

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Now that you already know so much about the universe, the big bang, our place in the universe, galaxies and how it all works, now we are going to discover amazing things in the universe that are made up of galaxies and other amazing stuff. Called a 'Super Cluster' or 'Super Clusters'

Super clusters are made up of many different galaxies. Some hundreds, some thousands, some hundreds of thousands. Galaxies are not spread out in the universe at random, but more packed together in groups based on where in the universe they started to form.

But we don't know if these clusters are exactly altogether like the way they look, as we don't really know if gravity keeps these clusters together. We like to put these together and call them groups and clusters to try make sense of it all. Confused!! We will explain further below.

So what you would know now is that while there are billions of stars and billions of galaxies, there are also great big spaces of nothing between all of these things.

So when scientists are observing the universe and galaxies they see large empty spaces and then clusters of stars. This makes for looking at space, kind of like looking at a sponge in your kitchen for washing up. Well, try and see, and you will get the picture.

From what we can see in the 'Observable Universe' we know of around a massive 10 million or so super clusters. These are great big clusters of galaxies that are as far as 100 million light - years away.

What makes galaxies super clusters is that over a very long period of time, galaxies collide to form these super clusters. One of the largest known super clusters in the universe is called the Sloan Great Wall.

This is one of the largest known things in the whole universe. This structure alone is a massive 1.4 billion light - years across.

# 1. The Milky Way galaxy is part of the super cluster called 'Virgo'

# 2. The largest super cluster ever discovered is 60 times largest than the Milky Way.

Q. What super cluster does the Milky Way galaxy belong to?

Q. How much larger is the largest known super cluster compared to the Milky Way galaxy?

Q. How many light years across is the Sloan great wall?

Q. What are super clusters made up of?

Q. How many super clusters are there that are known currently?

Download questions about super clusters here: super clusters (answers are on this page)

For further reading and more information on super clusters visit https://wiki.kidzsearch.com/wiki/Supercluster

Key Vocabulary Universe. Big Bang. Galaxies. Super. Clusters.

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Now that you know already so much about the universe, The Big Bang, Our Place in the Universe, Galaxies and how it all works, now let's talk about an amazing thing in the universe that is made up of galaxies and matter. Called 'Super Clusters'

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The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist.

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Astronomers map out Earth's place in the universe

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Astronomers map out Earth's place in the universe

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Astronomers map out Earth's place in the universe among 'Council of Giants'

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We live in a galaxy known as the Milky Way - a vast conglomeration of 300 billion stars, planets whizzing around them, and clouds of gas and dust floating in between.

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Where in the universe is the earth? Learn this and other facts at The Physics of the Universe.