Black holes don't emit any radiation (except for an insignificant amount of Hawking radiation). However, if matter falls onto a black hole, it will emit x-rays before it reaches the event horizon (the point of no return), as a result of an enormous acceleration.
Black holes emit so very little radiation they are hard to see. Many black holes lie at the center of galaxies and there they are hidden by stars and dust.
Due to light being unable to escape the black hole, we cann't see it! It's like trying to see in a dark room with a flashlight, that has dead batteries. You cann't see the light because their is none to reflect.
The whole idea of black holes is that nothing, not even light, can escape from them. However, there are several indirect ways to detect them.
You can't see a black hole.
You can't see a black hole.
Scientists can detect black holes by using x-rays and gamma rays. Black holes still can release matter, and black holes give off a lot off x and gamma rays.
Black holes are located throughout the universe, often at the centers of galaxies. They can also be found in binary systems with other stars. Some black holes are remnants of massive stars that have collapsed, while others are supermassive black holes at the center of galaxies like our own Milky Way.
Black holes are blavk because their gracity is so strong that light cannot escape for us to see.
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There is enough evidence for black holes - I don't see any problem there.
The assumptions are not quite correct.Scientists CAN see black holes. In fact, black holes are among the brightest objects in the Universe. Of course, light can't escape from WITHIN the black hole; rather, what we see is the accretion disk. Also, scientists are PRETTY SURE that black holes are real. As to why it is important: Black holes are fascinating objects by themselves. They also seem to play an important role in galaxy formation.
None. Black holes are completely black, making them invisible, so it would be pointless to put something you can't see in a constellation.