Have you ever wondered how you would answer if an alien asked you where you live?Your first reaction might be the name of the street where you live. You might also tell me where you are from.
If you're on vacation, you might even clarify which state or country you're from. If you answer Earth, they may not even have a concept of Earth.
That way, you might have to tell them which galaxy you live in. Have you ever considered yourself a resident of a galaxy? No doubt, you are a resident of the galaxy.
1. The origin of the name of the Milky Way
You probably see pictures of the Milky Way from time to time. None of these images were captured by real photography because we've never sent a spacecraft out of the Milky Way. However, special telescopes allow astronauts to learn more about the Milky Way.
And its name comes from its fuzzy, creamy white appearance. Most of the stars in the Milky Way are so far away from the Earth that on a clear and moonless night, they appear as a whitish band of light, commonly known as the Milky Way, the Milky Way or the Milky Way.
2. The composition of the Milky Way
The Milky Way is a huge celestial system composed of more than 200 billion stars (including the sun) and other substances. Basically shaped like an oblate disk, its diameter is about 80,000 light-years and its mass is about a trillion suns.
90% of the mass of the Milky Way is stars. There are many kinds of stars. According to their physical properties, chemical compositions, spatial distribution and motion characteristics, stars can be divided into five star groups.
The youngest extreme population I stars are mainly distributed in the spiral arms of the galactic disk; the oldest extreme population II stars are mainly distributed in the galactic halo. Stars often clump together.
3. The two companion galaxies of the Milky Way
The Milky Way has two companion galaxies (satellites): the Large Magellanic Cloud and the Small Magellanic Cloud. Galaxies opposite the Milky Way are called extragalactic galaxies.
The Milky Way, Andromeda and Triangulum are the three main galaxies in the Local Group of galaxies. There are about 50 galaxies in the Local Group of galaxies, and the Local Group of galaxies is a member of the Local Supercluster of galaxies.
4.The weight of the Milky Way
In 2020, an international research team used NASA's Hubble Space Telescope and the European Space Agency's "Gaia" probe to carry out the most accurate "weighing" of the Milky Way to date, arguing that the Milky Way has a mass equivalent to about 1.5 trillion suns. quality.
Of the total mass of the Milky Way, about 200 billion stars and a supermassive black hole at the center of the Milky Way account for only a small proportion, and most of the mass comes from dark matter. This invisible, mysterious substance acts like the "scaffolding" of the universe, holding stars in place in galaxies.
With the continuous development of science and technology in the world, people can use higher-tech space telescopes to explore and travel the vast galaxy, and human beings' understanding of the galaxy is also deepening step by step.
I believe that in the near future, we humans will find that we are not alone in the Milky Way or other galaxies in the universe! The universe is so big, let's go and see it together!
