All about the Milky Way

Our Sun (a star) and all the planets that orbit it are part of the Milky Way Galaxy. A galaxy is a large collection of stars, gas, and dust that are held together by gravity. They are available in a variety of shapes and sizes. 

 

The Milky Way Galaxy is a massive barred spiral galaxy. All of the stars visible in the night sky are part of our own Milky Way Galaxy. When viewed in total darkness, our galaxy is known as the Milky Way because it appears as a milky band of light in the sky.

 

Who Discovered the Milky Way?

 

The Milky Way appears to us on Earth as a band of diffuse light arcing across the night time sky. The English name comes from the Romans, who called it Via Lactea and imagined it as a band of spilled milk. 

 

Astronomers and philosophers debated the nature of the Milky Way until Galileo Galilei observed it with a telescope and discovered that the Milky Way's light comes from an infinite number of distant stars. The stars are too far away to see individually, but their combined light creates the familiar band.

 

Until the early 1900s, astronomers assumed that the Milky Way contained all of the universe's stars (either the Milky Way extended to fill the entire cosmos, or it was a finite size and surrounded by an infinite void). 

 

According to Britannica, astronomer Edwin Hubble made detailed observations of the Andromeda Nebula in the early 1920s, revealing that it was its own "island" of stars — a galaxy in its own right — located millions of light-years away from us.

 

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What is the Milky Way?

 

What exactly is the Milky Way? It is the name given to the entire galaxy we live in by astronomers, not just the part of it visible in the sky above us as that river of light. If all of this seems perplexing, we must acknowledge the importance of giving our galaxy a name. 

 

Many other galaxies are designated by catalog numbers rather than names, such as the New General Catalog, which was first published in 1888 and simply assigns each a sequential number. These galaxy names are unromantic, belying the dazzling beauty of the objects to which they are attached. 

 

However, other galaxies, particularly those brighter, closer galaxies that appear as more than just fuzzy smudges of light in a telescope, were given names based on their appearance by astronomers in the 17th and 18th centuries: the Pinwheel, the Sombrero, the Sunflower, the Cartwheel, the cigar, and so on. 

 

These names were given to galaxies long before there were systematic sky surveys that necessitated the use of numerical labeling systems due to the sheer number of galaxies discovered.

 

Our galaxy does not appear in any galaxy index. However, there was a need for a name to refer to it by. As a result, we refer to it as "The Milky Way" rather than "the galaxy" or "our galaxy."

 

Our galaxy, the Milky Way, is one of billions in the universe. Estimates of how many stars exist within the Milky Way vary greatly, but it appears to be between 100 billion and twice that number. Simply because counting the number of stars in the galaxy from our vantage point on Earth is so difficult. It's the same from our vantage point in the galaxy.

 

Because we couldn't see the structure of the Milky Way from our vantage point within it, we didn't even realize we were living inside a galaxy for most of human history. Indeed, we had no idea what a galaxy was: a vast city of stars separated from one another by even greater distances.

 

Most of the other galaxies in the sky were invisible without telescopes. The naked eye can only see three of them: from the Northern Hemisphere, we can only see the Andromeda galaxy, also known as M31, which is about two million light-years away and is the farthest object we can see with our eyes alone under dark skies.

 

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Size and Structure of Milky Way

 

Size

 

Harlow Shapley, an American astronomer, made the first reliable measurement of the size of the Galaxy in 1917. He calculated the size of globular clusters by observing their spatial distribution. Shapley discovered that, rather than being a relatively small system with the Sun near the center, as previously thought, the Galaxy is massive, with the Sun closer to the edge than the center.

 

 Assuming that the globular clusters outlined the Galaxy, he calculated that it has a diameter of approximately 100,000 light-years and that the Sun is located approximately 30,000 light-years from the center. (A light-year is the distance traveled by light in a year, which is approximately 9,460,000,000,000 km [5,880,000,000,000 miles].) His values have stood the test of time admirably.

 

The stellar disc of the Milky Way system is roughly as large as Shapley's model predicted, with neutral hydrogen being slightly more widely dispersed and dark (i.e., unobservable) matter possibly filling an even larger volume than expected. 

 

The system's most distant stars and gas clouds have been determined to be approximately 100,000 light-years from the galactic center, while the Sun's distance from the center has been determined to be approximately 25,000 light-years.
 

 

Structure

 

The structure of the Milky Way Galaxy is typical of a large spiral system. This structure is made up of six distinct components: (1) a nucleus, (2) a central bulge, (3) a disc (both thin and thick), (4) spiral arms, (5) a spherical component, and (6) a massive halo. Some of these elements blend together.

 

 

Formation and Evolution of Milky Way

 

The Milky Way began to evolve when clouds of gas and dust began to collapse, pushed together by gravity. The Milky Way Galaxy is about 13.6 billion years old. The evolution of the galaxy, on the other hand, remains a mystery.

 

According to ESA, Gaia measures the exact positions and distances of over 1 billion stars, as well as their light spectra, allowing scientists to understand the stars' composition and age. There is also evidence that the Milky Way collided with a number of smaller galaxies as it evolved.

 

A team of Dutch astronomers discovered a group of 30,000 stars moving in sync through the sun's neighborhood in the opposite direction as the rest of the stars in the data set in 2018. Even today, the Milky Way continues to devour smaller galaxies.

 

A galaxy called Sagittarius (not to be confused with the black hole) is currently orbiting close to the Milky Way and has most likely smashed through its disc several times in the last 7 billion years. 

 

Using Gaia data, scientists discovered that these collisions triggered periods of intense star formation in the Milky Way and may even be related to the galaxy's distinctive spiral shape.

 

 

Where is Milky Way Situated?

 

The Milky Way is home to two major satellite galaxies, the Large and Small Magellanic Clouds, as well as dozens of smaller satellites. The Andromeda galaxy, about 2.5 million light-years away, is our nearest neighbor. 

 

According to Swinburne University, the Milky Way, along with Andromeda and about 80 smaller galaxies, is a member of the Local Group, which is a group of galaxies about 10 million light-years across that are held together by their common gravity.

 

As per Durham University, the Local Group is part of a larger structure known as the Virgo Supercluster, which is surrounded by several large intergalactic voids. 

 

The Virgo Cluster, a massive collection of 1,000 to 2,000 galaxies located 54 million light-years away, is at the heart of this supercluster. The Virgo Supercluster is thought to be part of a larger structure known as the Laniakea Supercluster.

 

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Interesting Facts about Milky Way

 

Below are some weird facts about the Milky Way

 

1. The Milky Way Is (Mostly) Flat

 

Our galaxy is a hundred thousand light-years across but only a thousand light-years thick. The sun and its planets are embedded in a curving arm of gas and dust within this flattened (though slightly warped) disc, placing the solar system approximately 26,000 light-years away from the galaxy's turbulent core. 

 

A swath of dust and stars encircles the galactic center, resembling a dollop of whipped cream slathered on both sides of a pancake.

 

2. The Milky Way has an unnoticed Halo

 

Our galaxy is composed of approximately 90% dark matter, or matter that cannot be seen, and approximately 10% "luminous matter," or matter that can be seen with our eyes. 

 

This large amount of dark matter creates an invisible halo, as shown by simulations of how the Milky Way spins. If dark matter did not exist, the stars in the Milky Way would orbit much faster than observed.

 

3. Earth has been around for 18 Galactic Years

 

The solar system is traveling through interstellar space at approximately 500,000 miles per hour. Even at that rate, traveling once around the Milky Way takes about 250 million years. 

 

The last time our 4.5-billion-year-old planet was in this location, continents fit together differently, dinosaurs were just emerging, mammals had yet to evolve, and the Great Dying, the planet's most profound mass extinction, was in progress.

 

4. The Milky Way is distorted

 

The Milky Way is a disc about 120,000 light years across with a central bulge about 12,000 light years in diameter. The disc, however, is not perfectly flat; it is warped as a result of our neighboring galaxies, the Large and Small Magellanic clouds. These two galaxies have been tugging on our galaxy's matter like a tug of war.

 

5. Monster Black Hole in the Center of the Galaxy

 

The supermassive black hole, known as Sagittarius A*, weighs more than four million times the mass of the sun. We've never seen this object up close because it's hidden behind dense clouds of dust and gas. 

 

Astronomers, on the other hand, have been able to track the orbits of stars and gas clouds near the galactic center, allowing them to calculate the mass of the cosmic heavyweight hidden behind the curtain. 

 

Supermassive black holes are thought to be parked in the cores of most galaxies, and some are so greedy for nearby matter that they shoot out jets of powerful radiation visible from millions of light-years away.

 

6. Milky Way is on the Move

 

The Milky Way, like everything else in space, is moving. The Earth orbits the Sun, the Sun orbits the Milky Way, and the Milky Way travels through space. 

 

The Cosmic Microwave Background radiation, which was left over from the Big Bang, is used as a reference point to calculate the velocity of objects in space. The Milky Way galaxy, which is part of the Local Group of galaxies, is estimated to be moving at 600 km/s or 2.2 million km/hr!

 

7. The Galaxy is a solitary island in a sea of stars

 

The Milky Way devours galaxies that approach too closely. Over the years, scientists studying the galaxy's outskirts have discovered about two dozen faint streamers of stars that are the remnants of previous galaxies. 

 

When the Milky Way's more powerful gravity ripped apart smaller galaxies, glittering strands of leftovers were left behind. The Dark Energy Survey team announced at the AAS meeting that it had discovered 11 more of these streamers, some of which have been given Aboriginal names.

 

8. We Socialize With Ancient Stars

 

The Milky Way is also surrounded by more than 150 ancient star clusters, some of which are among the universe's oldest. These primordial stellar conglomerates, known as globular clusters, live in the Milky Way's halo and orbit the galactic center. Each one is densely packed with hundreds of thousands of stars. 

 

There are dozens of satellite galaxies orbiting the Milky Way; most of these are difficult to see, but the Small and Large Magellanic Clouds glisten each night in the southern sky.

 

The Milky Way is made up of a bar-shaped core region that is surrounded by a warped disc of gas, dust, and stars. The Milky Way Galaxy is the one in which we live. It is a spiral-shaped galaxy with hundreds of billions of stars, including our Sun. It is approximately 100,000 light-years across and 10,000 light-years thick.

 

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Our galaxy is known as the Milky Way because it appears as a milky band of light in the sky when viewed in complete darkness. From our vantage point within the galaxy, counting the number of stars in the Milky Way is extremely difficult.