However, near a black hole, gases and dust and stars encounter its tug. Some things may be hurtling by so fast they won't get pulled into the black hole. Other things may not be as swift. They will be drawn in.

Closer and closer, the tugging force gets stronger and stronger. Close enough, the black hole no longer acts like a whirlpool.

With a whirlpool, there's always a fast-enough fish—or a fast-enough something—that moves so quickly it won't be pulled all the way into the center.

Not so with a black hole! Within a certain distance the black hole's power is so strong, nothing is fast enough to zip away.

What is being compared or contrasted in this excerpt?

A comparison between the power of a star and the power of a whirlpool is being made.
A contrast between the power of a star and the power of a whirlpool is being made.
A comparison between the power of a black hole and the power of a whirlpool is being made.
A contrast between the power of a black hole and the power of a whirlpool is being made.