Read this excerpt from A Black Hole is NOT a Hole.

But you know what?

A black hole isn't a monster. It's not even alive. That means it can't lurk, eat, or belch. It has no dark, destructive desires.

Of course, you may have already figured this out. But you know what else?

A black hole is NOT a hole—at least not the kind you can dig in the ground or poke your finger through.

You can't just walk along and fall into one.

A black hole isn't a hole like that.

If a black hole is not a hole, then what in the universe is it?

In this introduction, the author clearly explains which purpose for her writing?

She will study black holes and define what they are.
She will study black holes and dig one in space.
She will study black holes and travel to see one.
She will study black holes and measure their depth.