国产热热热精品,亚洲视频久久】日韩,三级婷婷在线久久,99人妻精品视频,精品九热人人肉肉在线,AV东京热一区二区,91po在线视频观看,久久激情宗合,青青草黄色手机视频

If you put enough matter (1) in one small place, it creates a black hole(2), a gravitational field (3)so intense that nothing, not even light, can escape from (4) it.

A black hole is an extremely weird object. Its intense gravitational field changes space and time in fundamental ways. Each black hole has only three measurable properties (5) : mass (6), electrical charge (7), and rotational momentum (8).

Most astronomers now believe that there is a stupendously huge black hole in the inner core of our galaxy, billions of times heavier than the sun. It spins (9) in the center of a rotating whirlpool (10) of hot gas and dust, slowly sucking (11) it in.