银河系（Galaxy）.docVIP

银河系（Galaxy） Galaxy Definition: the galaxy where the earth and sun lie. The Great Southern Star system is the Milky Way the Milky Way Department of the solar system, including one hundred and twenty billion stars and a large number of star clusters, nebulae, and various types of interstellar gas and interstellar dust. It is about more than 100000 light-years across and has a central thickness of about 12000 light-years, with an edge of about 3000~6000 light-years. The total mass is 140 billion times the mass of the sun. The Milky Way system is a spiral galaxy, with a vortex structure, that is a center and two arms, arms 4500 light-years apart. The sun lies on the arm of the Milky Ways Orion Arm, about 26000 light-years from the center of the galaxy. The Milky Way center distance of about 26 thousand and 400 light-years, counterclockwise (the sun around the galactic rotation about 250 million years). The suns rotation speed of about 220 km / sec, the sun around the Galactic operation a week for about 250 million years. The total mass of the Milky way is about 1 trillion times the mass of our sun, roughly 10 times the mass of all stars in the Milky way. The galaxy was born shortly after the big bang, and our Milky Way galaxy is about 14 billion 500 million years old, with up to about 2000000000 years of error. The scientific community believes that the big bang occurred about 13 billion 700 million years ago. The galaxy is about 80 thousand light-years across. Thorium has a half-life of about 14 billion years. The first generation of stars in the Milky way have very large masses, more than 100 times the mass of the sun. These first formed stars have died and disappeared for a long time. From the big bang, the universe is about 14 billion years old. The age of the galaxy is estimated to be about 13 billion 600 million years old, almost as old as the universe. It is estimated that globular clusters are about 134 or 800 million years old, so the galaxy is no less than 136