Black Hole

天文學家和科學家對宇宙中黑洞的成因和本質進行了長期的探索，在此過程中解釋了一系列宇宙現象，并加深了對浩渺宇宙空間的認識。

What is a black hole？ Astronomers and scientists think that a black hole is a region of space into which matter has fallen and from which nothing can escape. So we can’t see a black hole. A black hole exerts a strong gravitational pull and yet it has no matter. It is only space - - or so we think. How can this happen？

The theory is that some stars explode when their density increase to a particular point； they collapse and sometimes a supernova occurs. From the earth， a supernova looks like a very bright light in the sky which shines even in the daytime. Supernovae were reported by astronomers in the 17th and 18th centuries. Some people think that the Star of Bethlehem could have been a supernova. The collapse of a star may produce a White Dwarf or neutron star - a star， whose matter is so dense that it continually shrinks by the force of its own gravity. But if the star is very large （much bigger than our sun） this process of shrinking may be so intense that a black hole results.

Imagine the earth reduced to the size of a marble， but still having the same mass and a stronger gravitational pull， and you have some idea of the force of a black hole. Scientists have called the boundary area around the hole the \"event horizon.\" We know nothing about events which happen once objects pass this boundary. But in theory， matter must behave very differently inside the hole.