Broad galaxy

The Milky Way is the galaxy to which the Earth and the Sun belong [1]. The bright band projected on the celestial sphere by its main part is named after the galaxy in China. The Milky Way is a disk-shaped star system consisting of more than 200 billion stars, thousands of clusters, and nebulae. The side of the Milky Way looks like a large disc with a center-drum. The entire disc is about 100,000 light-years across. The sun is located at 30,000 light-years from the center of the Milky Way. The bulging part is the heart of the silver heart, so I hope to go to the white. The Milky Way overlooks a huge vortex that has four spiral arms. The solar system is located in one of the spiral arms and rotates counterclockwise.

The Milky Way Galaxy is a spiral, with four spiral arms extending uniformly symmetrically from the center of the Milky Way. The center of the Milky Way and the four spiral arms are densely populated. There are 9.4608 trillion kilometers. The thickest part in the middle is about 12,000 light years. The sun is on a spiral arm called the Orion's arm, about 230,000 light years from the center of the Milky Way.

The discovery of the Milky Way has gone through a long process. After the invention of the telescope, Galileo first observed the Milky Way with a telescope and found that the Milky Way was composed of stars. Then, T. Wright, I. Kant, J. H. Lambert and others believe that the Milky Way and all stars may be assembled into a huge star system. Late 18th century, F. W. Herschel used a self-reflecting telescope to start the observation of the star count to determine the structure and size of the star system. He asserted that the star system was flat and the sun was not far from the center of the disk. After his death, his son J. F. Herschel continued his father's business and continued to conduct in-depth research to extend the work of star counting to the South. At the beginning of the 20th century, astronomers referred to the galaxy system with the galaxy as an apparent phenomenon as the Milky Way. J. C. The Kaputan method uses statistical parallax method to determine the average distance of stars, and combined with the star count, a model of the Milky Way is obtained. In this model, the sun is centered, the Milky Way is disc-shaped, with a diameter of 8 thousand seconds and a thickness of 2 thousand seconds. H. Shapley used the Zhouguang relationship of the Cepheid variable star to determine the distance of the globular cluster and study the structure and size of the Milky Way from the distribution of the globular cluster. The model he proposed was: The Milky Way is a lenticular star system, and the sun is not at the center. Shaplei concluded that the Milky Way is 80 kilometers in diameter and the sun is 20 kiloseconds away from the silver heart. These values ​​are too large because Shapley does not count for interstellar extinction when calculating distances. In the 1920s, after the discovery of the Milky Way rotation, Shapley's Milky Way model was recognized.

The Milky Way is a giant spiral galaxy, Sb type, with a total of 4 spiral arms. Contains one or two hundred billion stars. The Milky Way's overall rotation is relatively poor. The sun's rotation speed is about 220 km/s, and the sun is running around the silver heart for about 250 million years. The galaxy's visual absolute magnitude is -20. 5, etc. The total mass of the Milky Way is about 1 trillion times that of our solar mass, roughly 10 times the sum of all the stars of the Milky Way. This is a strong evidence of the existence of dark matter in our galaxy that extends far beyond the bright stellar disk. Regarding the age of the Milky Way, the current mainstream view is that the Milky Way was born shortly after the big explosion of the universe. Using this method, we calculate that the age of our Milky Way is about 14.5 billion years old, with an error of more than 2 billion. year. The scientific community believes that the "big bang" of the birth of the universe occurred about 13.7 billion years ago.

My feelings are: Universe = Milky Way * 10000, from which I feel the greatness of the universe, the data just estimated, so I think that only now can learn to open a new door between man and new.

Hongyuan Middle School, the first day: Yu Chao