Expert: Jayendra Upadhye - 2/19/2005

Question
meaning of black hole

Answer
Hi rose,
It would help if you told me your grade, so i could decide how simple or complicated an answer to give.
A black hole is the remnant of a large star that was, in its youth,  4-5 times the mass of the sun.
In its death, it leaves behind a "cinder" that is so small, made small by self gravity, that it becomes a true "point".

This happens because large stars of that size have very strong gravity anyway.

In such cases, light is unable to escape the "point source" remnant and so it is called a "black hole".

The boundary from where this starts to happen is much larger than the "point" discussed above, and is called the "event horizon".
Is this much info good enough?

Ver large black holes (not size wise, but mass wise) reside in centers of most spiral galaxies, including our one!
Jayen