Genre Definition and Recommendation is a feature where I will define a genre and a sub-genre definition and the make some recommendations.
Science Fiction - Definition found on Wikipedia
Science Fiction- is a genre of fiction dealing with imaginary but more or less plausible (or at least non-supernatural) content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities.
Space Opera (Space Travel) Definition found on Wikipedia
It's a night like any other on board the Icarus. Then, catastrophe strikes: the massive luxury spaceliner is yanked out of hyperspace and plummets into the nearest planet. Lilac LaRoux and Tarver Merendsen survive. And they seem to be alone.
Lilac is the daughter of the richest man in the universe. Tarver comes from nothing, a young war hero who learned long ago that girls like Lilac are more trouble than they’re worth. But with only each other to rely on, Lilac and Tarver must work together, making a tortuous journey across the eerie, deserted terrain to seek help.
Then, against all odds, Lilac and Tarver find a strange blessing in the tragedy that has thrown them into each other’s arms. Without the hope of a future together in their own world, they begin to wonder—would they be better off staying here forever?
Everything changes when they uncover the truth behind the chilling whispers that haunt their every step. Lilac and Tarver may find a way off this planet. But they won’t be the same people who landed on it.
Starglass by Phoebe North
Terra has never known anything but life aboard the Asherah, a city-within-a-spaceship that left Earth five hundred years ago in search of refuge. At sixteen, working a job that doesn't interest her, and living with a grieving father who only notices her when he's yelling, Terra is sure that there has to be more to life than what she's got.
But when she inadvertently witnesses the captain's guard murdering an innocent man, Terra is suddenly thrust into the dark world beneath her ship's idyllic surface. As she's drawn into a secret rebellion determined to restore power to the people, Terra discovers that her choices may determine life or death for the people she cares most about. With mere months to go before landing on the long-promised planet, Terra has to make the decision of a lifetime--one that will determine the fate of her people.