Cathy Sweeney, age 12, of Costa Mesa, California, for her question:

Does a star ever die?

We might say that a star lives as long as it continues to burn. Astronomers tell us that this life span may last less than a million years or longer than ten billion years. This depends on how fast a star burns up its burnable gas, which is hydrogen. At last, all its hydrogen fuel is burned to ash, which is mostly helium plus various solid substances. The blazing star dims and finally its fires go out. At this point we might say that the star dies.

Our starry sun is an old timer. It has been blazing away for some five billion years and still has enough hydrogen fuel to last at least another five billion years. But eventually, like all stars, it too will die. Astronomers predict that it will become a great ball of cold dark ashes    and travel on in the universe forever. Long before that happens, earthlings will pack up their belongings and space travel themselves to another suitable planet, orbiting around a younger sun.