Twelve-year-old Nova Vezina, a mostly nonspeaking autistic girl who loves astronomy, has spent most of her life in foster care with her older sister Bridget, the only person who understood how intelligent she really was. But now Bridget has gone missing, and Nova has been placed with new foster parents Billy and Francine West. At her new school, Nova befriends her special ed classmates, who become her first social group. Meanwhile, she impatiently awaits the launch of the space shuttle Challenger, because Bridget said that she'd come back before it happened.
Planet Earth Is Blue contains examples of:
- Alliterative Family: Billy and Francine's adult children are named James, Joseph, John, and Joanie.
- Bitch Slap: Bridget disappeared after a fight with their last foster mother, when the foster mother slapped her in the face.
- Bittersweet Ending: Challenger explodes and Nova realizes that Bridget was Dead All Along and has to accept it. But Francine and Billy finally understand her and she’s starting to heal. The book ends with Francine and Billy planning to fully adopt Nova.
- Conspiracy Theorist: Nova and Bridget used to live with their mama, who believed that the moon landings had been faked and would watch TV static for secret government messages.
- Death Is a Sad Thing: Bridget and her boyfriend were killed in a car accident; Nova was in the car when it happened. At the hospital, she heard people saying she was the sole survivor, but she didn't know what "sole" meant and thought Bridget had run away with her boyfriend, as she had been planning to do before the accident.
- Deliberate Values Dissonance: Due to the lack of understanding of autistic children, especially nonverbal ones like Nova, she’s treated like a dunce and infantized at best and outright abused at worst. Even her current foster parents have trouble understanding her at first.
- Disappeared Dad: Nova and Bridget's father never returned home from Vietnam. Their mama thought it was because he knew the truth about the government's communist plot.
- First Friend: Nova decides that her special ed classmate Mallory is her first friend after two bullies insult Nova and Mallory says, "I don't let anybody be mean to my friends."
- Foster Kid: Nova and Bridget have been in the system since the former was five and the latter was eight.
- Hates Being Touched: Nova hates the feeling of anyone's skin on hers except Bridget's.
- Held Back in School: When Nova first starts classes at Jefferson Middle School, she's unhappy to learn that she'll be placed in sixth grade, even though she was already halfway through seventh.
- The Illegible: Nova is believed to be incapable of reading and writing. In fact, she can write, but Bridget is the only person who can read her handwriting. To everyone else, it looks like meaningless scribbles.
- Percussive Maintenance: On the day of the Challenger launch, the TV set shows only static. The teacher hits the side, and the image comes into focus.
- Potty Dance: On Nova's first day of school, a teacher asks her if she has to go to the bathroom after she starts squirming.
- Promoted to Parent: When Nova and Bridget still lived with Mama, Bridget was the most mature and responsible member of the family. After they were removed, Bridget took care of Nova all the years they were in foster care.
- Security Blanket: Nova's NASA Bear, which was given to her by her mother, and which she takes everywhere.
- Sensory Overload: Nova struggles with this. She covers her ears in the hallway on the way to class. Part of the reason she does so badly on every intelligence test is that the classroom noises distract her and make it hard to hear what the teacher is saying.
- Sore Loser: When Nova beats Mallory at Chutes and Ladders, Mallory swears, throws her game piece, and knocks the board on the floor.
- The Speechless:
- Nova can make approximations of one-syllable words, with effort. People usually don't understand her, and for the most part she doesn't find speech to be worth it.
- Buddy, a boy from her special ed class, can't talk but can make some signs.
- Margot, another kid from the class, sits in her wheelchair with her head tilted to the side, not talking.
- We Need a Distraction: During a baking elective, Mallory tells Nova to make a distraction by screaming. While everyone is looking at Nova, Mallory gets revenge on two bullies by turning their oven up to 450 degrees, ruining their cookies.
