A.the star is going to die |
B.special tools are used on it |
C.other stars come close to it |
D.it is seen from the space telescopes |
A.A black hole can be very tiny but extremely heavy. |
B.The gravity of a black hole holds all light in its center. |
C.Scientists observe high-energy light through their own eyes. |
D.Some small black holes came into being as early as the universe. |
A.Every galaxy must have a black hole. |
B.A galaxy is the center of the universe. |
C.A galaxy consists of a large group of stars and planets. |
D.Earth’s galaxy is called the Milky Way. |
A.Neither the sun nor the earth is as heavy as a black hole. |
B.There is only one supermassive black hole at the center of the Milky Way. |
C.The supermassive black hole had existed before the Milky Way was formed. |
D.There is a reason why the large black holes are called “supermassive”. |
A.what a black hole is |
B.how black holes form |
C.how big black holes are |
D.how scientists know about black holes |