Transcript for Remnants of Chinese rocket hurtles toward Earth
We begin tonight with that breaking news -- part of a Chinese rocket nearly as tall as a ten-story building hurdling towards Earth. It's one of the largest pieces of manmade space chunk to ever make this drop. The mission blasting off last week carrying the module of China's space station into orbit. This image believed to show it over Italy. The body of that rocket dropping to a low orbit, circling Earth. Putting it into a position where it would crash land. But the timing and final path is unpredictable, raising concerns. ABC's transportation correspondent gio Benitez leads us off. Reporter: Tonight, a massive part of this rocket launched by China just days ago crashing towards Earth. The section of the long March 5b among the largest space junk to ever fall to the Earth, roughly the size and weight of a semitruck. Threatening a large swath of the planet. The U.S. Military closely monitoring its descent. We're hopeful it will land in a place where it won't harm anyone, hopefully in the ocean. Reporter: But that's not a given. The portion of the rocket, weighing 23 tons, roughly ten stories tall, speeding to Earth at 18,000 miles per hour could land anywhere from Mexico, central and South America to right here at home in America. To parts of Africa, even Australia. The aerospace corporation tracks space debris. This is an uncontrolled reentry. For something that big, that's unusual. Reporter: Manmade space debris has fallen before, though it's usually small or doesn't fall on land. In Washington state, this piece from a spacex rocket landed on someone's property in March. And in Tulsa, Oklahoma, Lotti Williams became the first known person to be hit by space junk in 1997. It looks like fire. It was this big ball of fire. You couldn't see anything, hear anything. You didn't smell anything. Reporter: Luckily the chunk did not injure her. Gio with the space race heating up, officials are worried this could happening more often in the future. Reporter: That's right, and it's not clear how countries would be held accountable. The white house hasn't said how they would handle it with China but the defense secretary said companies operating in the domain should be required to do it safely. Whit? We'll be watching the sky. Gio Benitez, thank you.
This transcript has been automatically generated and may not be 100% accurate.