2023-10-27 23:40:36
Jongjin Park Countless stars twinkle in the night sky. Of course, there are planets in the solar system such as Mercury and Venus, but there are also galaxies, which are groups of stars. A galaxy is a collection of stars ranging from as few as 10 million stars to as many as trillions, but they are so far away that they look like a single star. The galaxy to which the star called the Sun belongs is called the Milky Way, and the closest neighboring galaxy to the Milky Way is the Andromeda Galaxy. There are regarding 400 billion stars in the Milky Way, and regarding 1 trillion stars are gathered in the Andromeda Galaxy. About 2 trillion such galaxies come together to form the universe. Whenever you open your mouth, the words ‘billion’ and ‘trillion’ come out, but these are units of measurement that we don’t usually use. That is why such large numbers are called astronomical numbers. It is said that it takes regarding 100,000 years to travel at the speed of light from one end of the Milky Way, where we belong, to the other. About 400 billion stars, including the sun, are bustling within it. About 2.5 million light-years away from the Milky Way is our neighbor, the Andromeda Galaxy. Andromeda’s diameter is regarding 220,000 light-years, making it twice the size of the Milky Way. The Andromeda Galaxy, which is so far away from us that it twinkles like stars in the night sky, was thought to be a collection of stars within our galaxy, or a nebula, until Edwin Hubble discovered the existence of an external galaxy, so it was also called the Andromeda Nebula. However, Hubble discovered that the nebula was an external galaxy outside our galaxy. It was a moment when the universe suddenly became hundreds of billions of times larger. The Andromeda Galaxy is 2.5 million light-years away from our galaxy, so even if you travel there at the speed of light, it would take 2.5 million years. If you think regarding common sense, the place we can never go to even if we die and wake up is the Andromeda Galaxy, which is said to be closest to the Milky Way. The part of the vast universe that the Milky Way belongs to is called the Local Group of galaxies, and there are only two galaxies of a certain size: Andromeda and the Milky Way. The rest are called satellite galaxies because they serve as bridesmaids. Our galaxy has dozens of satellite galaxies around it, so strictly speaking, the closest galaxy to the Milky Way is not the Andromeda Galaxy, but excluding such small satellite galaxies, it is the closest neighboring galaxy among independent galaxies with their own appearance. Among the satellite galaxies around the Milky Way, the Large Magellanic Cloud and the Small Magellanic Cloud are visible to the naked eye. The Andromeda Galaxy is the brightest galaxy among the 40 galaxies in the Local Group of galaxies that the Milky Way belongs to, and has a spiral shape like our Galaxy. It is 2.5 million light-years away from the Milky Way, so we are now looking at the Andromeda Galaxy as it was 2.5 million years ago. If you let go of the nail you are holding in your hand, it falls to the ground. This is because the Earth’s gravity pulls it. This time, if you place a magnet close to a nail that has fallen on the ground, it will stick immediately. This is evidence that electromagnetic force is much stronger than gravity. Even though gravity is so small, the situation is different in the macroscopic world. It is said that the Milky Way and Andromeda are attracted by each other’s gravity and are currently getting closer to each other at regarding 100 km per second, but in 4 billion years the two galaxies will collide and merge. Milkomeda Galaxy, a combination of the two names Milky Way (Milky Way) and Andromeda, is the name of a new galaxy that will be formed in 4 billion years. (Writer) Jongjin Park
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