If you enjoy stargazing, or are often fascinated by the cryptic night sky, you sure would be interested in learning more about stars and the Milky Way.
If that’s so, you are definitely in the right place. Here, we have gathered some mind-blowing information about the Milky Way galaxy and the countless stars that it contains.
For those of you who often wonder how many stars are out there, the answer would be 150 billion. Or perhaps 300 billion. Or maybe 400 billion. The thing is, that even after years of research, scientists don’t know the answer for sure. Why?
Well, to begin with, stars can be hard to identify. Not every star shines brightly, which means that even with the most sophisticated technology, it can be difficult to spot stars, especially if they have a low mass or are far more distant than others. Plus, if you really understood how tremendously vast our galaxy is, you will automatically understand why it’s impossible to count the number of stars within the Milky Way.
What Is the Milky Way?
Milky Way, the galaxy in which the Earth and thus, the solar system that we know of, resides, is an enormously large collection of interstellar gas, dust, and billions of stars held together by a central force of gravity.
From observations, scientists believe that it is approximately 100,000 lightyears wide. To give you a fair idea, one lightyear is almost equal to 10 trillion km (or about 6 million million miles).
The whole galaxy is surrounded by a huge hot-gas halo that is almost as massive as the billions of stars and planted contained within it.
If you could view the Milky Way from the outside, it would look like a large spiral with four distinct arms, two big and two small. The major arms are called Sagittarius and Perseus. Our solar system can be found in one of the two minor spurs, known as the Orion–Cygnus Arm, Local Spur, Orion Bridge or simply, Orion Arm. This arm alone is about 3,500 lightyears wide and approximately 10,000 lightyears long.
In the middle where these arms join is the ‘central bulge.’ It is a tightly packed group of stars that is nearly spherical in shape. The Milky Way Galaxy also has a supermassive black hole in the middle. It provides the gravitational pull that keeps all the galactic bodies floating in the form of a cluster.
The Belt of Stars That We See
You have seen it in movies and have come across breathtaking images online (if not directly outside your window) – the broad swath of heavenly light speckled with millions of stars shining like silver sand. That indeed is the Milky Way galaxy.
The term Milky Way comes from the Greek word galaxias, which means milky circle. The band has been visible since the beginning of time and was described by the ancients as a ‘river of milk.’ It appears like a ribbon because we are viewing it from within.
As we mentioned earlier, our solar system is located on one of the arms of the Milky Way. This means that the intriguing line of light that we see is basically the center of our galaxy.
On a really dark and clear night, in areas that are virtually free of pollution, you can even see clouds of interstellar dust that surround the spangled stars. However, it’s hard to see across the dense center of the galaxy – not just for us, but even for the scientists.
This is mainly because the galactic bulge in the middle is so heavily populated with space bodies that even the most powerful telescopes cannot see through it.
Stars and the Milky Way
It might surprise you to know that Galileo Galieli was the first to resolve the band of light into individual stars using his telescope in 1610. Almost three centuries later, scientists believed that the Milky Way was the only galaxy to contain all the stars. But in 1920, Edwin Hubble made a breakthrough observation that the Milky Way was, in fact, only one of the many galaxies out there.
Now it’s easy to ask how many stars are in the Milky Way galaxy, but difficult to answer it. It’s pretty much like trying to figure out how many grains of sand are there on a given beach – you can never actually count them. However, scientists’ ‘educated guess’ is that there about 10^11 stars in our galaxy. The interesting part is that there is almost the same number of galaxies in the Universe.
So, if you want a ballpark figure for the total stars in the Universe, that would be about 10^22 (i.e., one sextillion or one thousand trillion stars in the observable Universe).
Keep in mind though that astronomers are continuously discovering new stars every day.
The Biggest Stars in the Milky Way
Twinkle twinkle little star…?
Trying to picture the actual size of these stars in the Milky Way that will put the centuries-old rhyme to shame.
V838 Monocerotis is the ninth-largest star in our galaxy, at a distance of almost 6,100 lightyears from Earth. It has a diameter of almost 500 million km and is about 380 times bigger than the sun.
Antares is a bright red supergiant star in the constellation of Scorpio. At 550 lightyears, it is relatively close to our planet than most of the other noteworthy stars in the galaxy. It is more than 800 times bigger than the sun.
Betelgeuse is slightly bigger than Antares but appears relatively smaller in the constellation of Orion as it is further away from the Earth (643 lightyears while Antares is only 550 lightyears away).
KW Sagittarii is a thousand times larger and about 7,800 lightyears away from the sun. It is found in Sagittarius, which is a constellation.
This star is an irregular variable, meaning that its diameter ranges between 690 and 1,520 times that of the sun. It is almost 9,000 lightyears away from our planet and is known as one of the most luminous stars in the Milky Way.
VY Canis Majoris
VY Canis Majoris is type of star known as a red hypergiant. This star is incredibly huge and bright (luminous), and it is believed to be the biggest galactic body in our Milky Way galaxy. It is more than 2000 times the diameter of our sun and is approximately 3,900 lightyears away. It is so massive that its own light takes eight earth hours to travel around its equator.
Spiraling Towards the End
The planets, gases, stars and the Milky Way itself are in constant motion. The galaxy is believed to be hurtling through space at a speed of approximately 600 km per second!
On the other hand, its nearest neighbor, the Andromeda Galaxy is spinning towards the Milky Way at a speed of 110 km per second. Scientists predict that in around 4 billion years, the two galaxies will collide with each other. However, the result won’t be as catastrophic as you might imagine.
A few million stars will be destroyed but our local solar system, or at least the sun and the earth, will survive. The newly formed mega-galaxy will then have millions and billions of more stars that will offer a truly mesmerizing night skyscape far more ethereal than what we see today. Too bad we won’t be here to witness that.
On a clear night, you can easily see a few hundred, if not thousands of stars shining in the sky. With the aid of a decent telescope, numerous more will come into view. All of them are part of the galaxy we call ‘The Milky Way.’
Scientists have been studying space for decades. But even after years of meticulous research, what they know about stars and the Milky Way is only a small fraction of what is really out there.
We hope that you made some intellectual discoveries while reading this article but as astronomers struggle to explore the hidden realms of our galaxy, all we can do for now is look into the night sky and admire the enigmatic view that is simply out of this world – quite literally!