Milky way galaxy Features + wonders

If you raise your head towards the sky, a wide and endless ceiling of countless beauties of the stars and the moon will caress your eyes. In every part of this vast sky, there are countless stars that watching and accessing them seemed attractive and of course impossible for mankind for a long time; But now there are fascinating images of the unknown and dark space that were taken by different telescopes. One of the most tangible elements of space is called the “Milky Way Galaxy”. A large and huge galaxy in which our solar system is located. In this article, we will travel to a corner of the secrets of this strange element of creation.

Everything you need to know about the Milky Way:

What is the Milky Way galaxy?

A galaxy, in its general sense, includes a large group of stars, gas, and dust that are bound together by gravity. In the boundless expanse of the sky, there are millions of galaxies, many of which are still unknown to us; But the galaxy of which planet Earth is a small part is called the Milky Way. This beautiful galaxy, which we consider our home, is a large spiral bar and has stretched its huge arms along the cosmos. Humanity has always sought its questions about the mysteries of this huge gas mass.

_{The Milky Way in the desert; Photo source: Wikimedia; Photographer: Chrdoerr}

Now, with the help of images taken by NASA’s Spitzer space telescope, scientists have discovered the existence of four arms around the Milky Way galaxy. In the past, it was thought that the Milky Way galaxy is dominated by two arms; But the new views, along with findings presented at the 212th meeting of the American Astronomical Society, show that more than two arms surround the galaxy. The two main arms are attached to the ends of the thick band at the center of the galaxy, and two much smaller secondary arms are located between these two main arms.

The main arms have the highest density of young and old stars, and the minor arms are mostly filled with gas. The Milky Way is about 13.6 billion years old and moves through the universe with its rotating arms. This galaxy can be thought of as a disk that is about 100,000 light-years in diameter and 1,000 light-years thick. The number of stars in our galaxy is estimated to be around 100 billion to 400 billion.

The reason for naming the Milky Way galaxy

If you look at the sky in the dark night sky and when there is no light pollution, the Milky Way galaxy is stretched like a milky band from one side of the sky to the other, and many stars are moving in the heart of it. According to Matthew Stanley, professor of the history of science, the first names referring to the Milky Way can be traced back to the ancient Greeks. Even Western astronomers used this term about 2,500 years ago; But it is not known who invented it and it is so old that its origin is now completely forgotten.

_{The Milky Way from Earth; Photo source: space; Photographer: getty}

The ancient Greeks have a legend and a story to name the Milky Way, which was immortalized by the great painter Tintoretto. According to this legend, the lion that Hera, the wife of the ancient god Zeus, gave to her child went to the sky and formed this galaxy in its place in the sky. In the past, the Milky Way was seen as a beautiful belt in the sky, and scientists realized that this galaxy has our home, the Earth, in its heart. For this reason, this galaxy had a special and important meaning for people, and such stories and legends were told about it. As time passed and telescopes progressed and images from the unreachable parts of space reached mankind, they realized that there are many more strange and giant galaxies throughout the galaxy. In this way, these galaxies were named after their discovery in the form of letters or abbreviated numbers.

Characteristics of the Milky Way

The first reliable measurement of the size of the Milky Way was made in 1917 by the American astronomer Harlow Shapley. At that time, Shapley realized that contrary to the previous idea that the Sun is at the center of a relatively small system, the galaxy we live in is very large and the Sun is located near the edge instead of the center. It was Shapley who estimated the diameter of the galaxy to be about 100,000 light-years and found that the Sun is about 30,000 light-years away from the center of the galaxy. The values ​​that he identified in those distant years have remained surprisingly constant.

_{A photo of the Milky Way from Earth; Photo source: NASA; Photographer: Telescope}

The most prominent part of the Milky Way galaxy is called “disk”; The disk extends between 75,000 and 100,000 light-years, and our galaxy, like other spiral systems, has a bright, flat structure of stars and gas clouds spread throughout the galaxy. The disk is the main body of the stars on which the arms of the galaxy are placed. Different parts of this disk have different thicknesses, with thicker parts containing older stars and thin parts containing younger stars.

Astronomers did not know until 1953 that the Milky Way has a spiral structure; Because the presence of interstellar dust and the inner position of the solar system made it difficult for the terrestrial observer to detect it. This type of spiral structure was detected by radio maps. The understanding of the spiral structure and the arms of the galaxy began to progress in the 50s and has grown significantly up to today; But still not all its dimensions have been determined. The interesting thing to note is that according to the calculations, this spiral pattern does not rotate with all the stars, but individual stars can enter and exit these arms as a result of rotation.

The Milky Way and the Solar System

The Milky Way galaxy is our home and for this reason we feel that our solar system and our huge sun are located in the heart of this galaxy. If we liken the center of the Milky Way galaxy to a city, the solar system and planet Earth are located somewhere on the outskirts of the city, at a distance of about 25,000 to 30,000 light years from the center.

_{Photo source: NASA; Photographer: Unknown}

Our life in the solar system flows in one of the two smaller spiral arms, which are located between the main arms of “Perseus” and “Carina”; The same place where the sun is seen in the photo below. In 2019, astronomers discovered that our solar system is immersed in a wave of interstellar gas 9,000 light-years long and 400 light-years wide.

As the Earth revolves around the Sun, the Solar System revolves around the center of the Milky Way Galaxy. The solar system moves at a speed of about 828,000 kilometers per hour and it takes approximately 230 million years to make a full circle around the center of the Milky Way galaxy, and this number shows the magnitude of our galaxy, which is currently a very gigantic galaxy compared to There are no other known galaxies.

The orientation of the solar system is different from the orientation of the galaxy. As in the image below, the farther we get from the sun and the closer we get to the edge of the galaxy and look at the solar system from afar, we see that the solar system is placed in front of the nebulae of the galactic core and the galactic equator can be seen horizontally behind it. According to this image, the plane of the solar system is tilted at an angle of 60 degrees to the plane of the galaxy and it rotates around the galaxy by maintaining this angle.

The orientation of the solar system with respect to the galaxy appears to be slightly different. As you can see in the image below, a little bit of the sun moves towards the edge of the galaxy and we look at the position of the solar system from a distance, which is placed in front of the nebulae of the galactic core and the galactic equator is also visible horizontally behind the image. The plane of our solar system is tilted at an angle of about 60 degrees to the plane of the galaxy. The plane of the solar system remains fixed while orbiting the galaxy and rotates around the galaxy at the same angle.

_{Photo source: oikofuge; Illustrator: Guillermo Abramson}

How many planets does the Milky Way have?

The planet we live in is a tiny speck in the vast Milky Way galaxy. This galaxy has a vast expanse to explore. Scientists cannot physically count every planet. Of the 800 billion to three trillion planets that may exist in the Milky Way, perhaps only about 5,000 have been physically documented so far.

About a decade ago, NASA estimated that there are 100 billion stars in the Milky Way, and on average there is at least one planet orbiting each star. However, further research showed that the number of stars can be doubled, and in the same way, the number of planets is also overestimated; However, we know that the solar system has 8 planets at one point of this big galaxy.

_{Photo source: worldatlas; Illustrator: Unknown}

The largest star in the Milky Way

The universe and the space we are talking about can have millions of millions of stars and huge planets that are even strange for our minds to imagine; But here we want to talk about the biggest star in our galaxy. This star is beyond our imagination. The star “UY Scuti” (UY Scuti) is one of the largest stars discovered in the universe and the largest star discovered in the Milky Way galaxy, which is more than 1,700 times larger than the Sun.

If we want to describe the mass of the star “Yo Y Scotti” in a way that is easier for our minds, you can fit more than five billion suns in this star. There is an interesting point and that is that this star, despite its huge size, is only 10 times the mass of our sun and 100 thousand times brighter; Because this star is in the final years of its life and stars expand at the end of their life and will explode at the end. This star also turns into a neutron star with a black hole after the explosion.

The black hole of the Milky Way galaxy

According to the research of scientists and astronomers, there is a huge black hole in the center of the Milky Way galaxy. This black hole is called “Sagittarius A” and in Persian language “Kaman-e” and it is also known by the same name because it is located in the constellation of “Sagittarius” or the bow from the point of view of an earthly observer. This black hole cloud is about four million times the mass of the Sun and about 23.5 million kilometers wide. Many things about this black hole are still unknown; Like how it was formed and the reason for its fast and uncoordinated rotation compared to the rest of the galaxy; But scientists and astronomers are not strangers to this black hole.

_{Photo source: space; Photographer: Hubble}

In 2022, telescope data recorded the first image of this black hole. The data also gave us a clue that the present-day “arc” was born from a catastrophic merger with another supermassive black hole billions of years ago, and the effects are still visible. Scientists think that this supermassive black hole, like other black holes, was created by the collapse of a supergiant star and then fed on everything that came close to it. A black hole like this one can feed on other galaxies or black holes after they grow bigger.

According to older studies, the bulges and twists of the galaxy indicated that the arc probably collided with at least 12 galaxies during the last 12 billion years; But scientists were still not sure whether the black hole of the galaxy was also fed by other black holes or it reached these dimensions only by consuming gas and dust. After studying the evidence obtained from the Event Horizon Telescope data, researchers found that our galaxy’s black hole formed about 9 billion years ago after merging with the Gaia-Enceladus galaxy and its black hole. , income in today’s form.

The wonders of the Milky Way

• Randomness on a spatial scale: One of the strange events that doesn’t add up to our age, but even knowing it is exciting and a little scary, is the collision between our galaxy and the neighboring galaxy “Andromeda” about four billion years from now. Currently, both of these galaxies are approaching each other at a speed of about 400,000 kilometers per hour.
• The invisible gas giant: It may be hard to believe; But everything we have ever seen, heard or read about the Milky Way applies to only 10% of the galaxy, and the remaining 90% of our galaxy is invisible. The findings give the possibility of the existence of density and matter that has volume; But it does not shine at all and we cannot see it; That is why it is called “dark matter”. Still no one knows what this substance is and what its components are.
• Real photo of the Milky Way: Every photo or image you see of the outer entirety of the Milky Way galaxy is either made by artists or belongs to another galaxy; That’s because we haven’t been able to photograph the outside of our own galaxy yet because we’re inside it. Maybe years from now, with ever-increasing progress, telescopes will be able to go out and take pictures of the galaxy.
• The origin of the Milky Way in Farsi: The name of the galaxy in Farsi is derived from the word “strawman” and it compares the galaxy to a strawman that is going away and the stars and dust of the Milky Way spilled out from inside and formed the present galaxy.
• The giant Milky Way is a corner of a larger universe: The Milky Way galaxy, in the heart of which our solar system is considered as a grain of sand in a large and vast desert, is itself a part of a larger structure that includes neighbors such as Andromeda. Our galaxy is part of the “Virgo Supercluster” along with 50 other galaxies.

_{Photo source: Wikimedia; Photographer: Y. Beletsky}

Your experience of observing the galaxy and stars is interesting for us. Please share your experiences of seeing the Milky Way with us.

_{Cover photo source: britannica; Photographer: Unknown}