IDU: What is space Junk?

In May of 2021, the remains of a 20-ton chunk of a Chinese rocket came crashing into earth. Surely you heard about it? In fact, maybe you were one of the people obsessively checking the internet for its latest trajectory...wondering where on earth (literally!) it was going to hit? It was the largest piece of man-made space debris to have an uncontrolled crash into Earth in nearly 30 years...and the US government warned that it was not out of the realm of possibility that it could come hurtling into an inhabited area. Well, fortunately the debris re-entered somewhere near the Maldives in the Indian Ocean and no one was hurt. But...it got me thinking: just how much stuff is up there? And how did it get there? And do I really need to also be worried that some piece of space debris could fall out of the sky? How big of a problem is this? SUNY Distinguished Professor John Crassidis joins William Shatner on this week's episode of "I Don't Understand" to discuss space junk.