WTF?! In what sounds like a potentially worrying scenario, a massive, "out-of-control" Chinese rocket that's falling to Earth could partially survive reentry and crash into the planet next week, but we don't know where it will land.

The Pentagon says it is tracking the trajectory of the Chinese Long March 5B rocket, which is expected to reenter the Earth's atmosphere on May 10. That's plus or minus two days so it could happen as early as May 8 or as late as May 12.

The Long March 5B's 30-metre (98.4-foot) high core launched the Tianhe or "Heavenly Harmony" unmanned module into low Earth orbit last week. It's the first module of China's space station that's expected to be fully operational by 2022.

The core stage is now also in orbit and heading for an uncontrolled reentry---you can watch its path here. While the atmosphere burns up most space junk, there are concerns that large parts of the 22-ton rocket could make it through and land on inhabited areas.

"It's potentially not good," Jonathan McDowell, Astrophysicist at the Astrophysics Center at Harvard University, told The Guardian. "Last time they launched a Long March 5B rocket they ended up with big long rods of metal flying through the sky and damaging several buildings in the Ivory Coast," he said.

The tumbling core's 17,149 mph speed makes it impossible to know where it will land. The "exact entry point into the Earth's atmosphere" won't be clear until within hours of reentry.

The good news is that we're in very little danger of being squashed by falling debris. With water covering 71% of the planet, an ocean landing is the most likely outcome.

"I don't think people should take precautions. The risk that there will be some damage or that it would hit someone is pretty small---not negligible, it could happen---but the risk that it will hit you is incredibly tiny. And so I would not lose one second of sleep over this on a personal threat basis," Jonathan McDowell, an astrophysicist at the Astrophysics Center at Harvard University, told CNN.

"What's bad is that it's really negligent on China's part. Things more than ten tonnes we don't let them fall out of the sky uncontrolled deliberately," McDowell added.