The excerpt from "A Black Hole Is NOT a Hole" that helps readers understand the appearance of a black hole is: "If you could somehow take a close-up of a black hole, it wouldn't make for an interesting photo. It would be blank and black. Near the event horizon of a black hole, the energy of light propels it at high speeds, akin to a fish swimming near the edge of a whirlpool." As light travels toward the black hole's center, where gravity is stronger, it changes direction. Scientists identify a black hole by looking for distinct patterns in the X-rays' rise and fall, much as you recognize a song through its melody's fluctuations in pitch and volume.

The excerpt from "A Black Hole Is NOT a Hole" is aiming to help the readers visualize what a black hole might look like and how it can be detected by scientists. It begins by suggesting that a black hole wouldn't actually look like anything in a photograph because it does not emit light itself; instead, it is completely black. It then introduces the concept of the event horizon, which is the boundary surrounding a black hole where light can no longer escape due to the strong gravitational pull. The excerpt paints a picture where light is personified as a fish swimming near a whirlpool, struggling against the black hole's gravitational 'current.' As light moves closer to the center of the black hole (where gravity is the strongest), it is pulled in different directions, ultimately getting trapped.

The last part of the excerpt describes how scientists are able to detect and identify black holes. They can't directly see black holes, since no light can escape from them, but they can observe the effects of the black holes on nearby matter. One of the ways scientists can identify a black hole is by looking for patterns in X-ray emissions that arise when matter gets heated to extreme temperatures as it is pulled into the black hole. These rising and falling patterns in X-rays are compared to the fluctuations in pitch and volume of a melody to describe how distinctive they are, which allows scientists to "recognize" a black hole much like recognizing a song.