* Simple: "The astronaut will reenter the Earth's atmosphere soon."
* Descriptive: "After a long journey, the spacecraft is preparing to reenter the planet's atmosphere, blazing through the sky like a fiery comet."
* Action-oriented: "With a jolt, the fighter jet reentered the combat zone, guns blazing."
* Figurative: "Her heart reentered the race when she received good news."
The best sentence for you will depend on the context and the specific meaning you want to convey.