If you’re on a dark countryside hill some night, 【小题1】 (look) up at the sky. A band(束) of light may appear that looks like milk spilled(洒落) across the sky. The ancient Romans called the band via lacteal which means "milky road" 【小题2】"milky way."
The band of light that you see isn’t actually milk, of course—it s a galaxy(星系). A galaxy can contain many millions of stars held together by the force of gravity. Our solar system, 【小题3】 includes the sun. Earth, and other planets, is part of this galaxy called the Milky Way.
The Milky Way 【小题4】 (make) up of hundreds of billions of stars like our sun. And like our sun, most of these 【小题5】(star) have at least one planet moving around 【小题6】(they). Earth is located about halfway between the center of the Milky Way and its outer edge.
At the center of the Milky Way is one of the 【小题7】(strange) and deadliest things in the universe: a black hole. 【小题8】 (scientist) believe a black hole lies at the center of most galaxies. The Milky Way’s black hole is called Sagittarius A*. Its gravity is 【小题9】strong that it pulls in anything that gets too close, including stars. So we’re 【小题10】 (luck) that Earth is located far away from the center!
