Transcript for Chinese space station tumbling toward Earth expected to crash this weekend
So a lot of us are keeping an eye on the sky this weekend. It's because of massive Chinese space station which was launched back in 2011678 it is tumbling towards planet Earth. It will happen and they're monitoring falling pieces that could hit the state. Joining us is form ma nasa astronaut Mike Massimino. He's a professor at Columbia university. Good morning. Is there danger here? Well, I can see why people would be concerned about a spaceship coming out of the sky hitting them in the head but I don't think that's going to happen. Very unlikely that it's going to hit anything. If these things happen, even though you're in space and you're in a vacuum when things are orbiting there still is a little atmospheric drag and particles and traveling so fast the drag generally will decrease your orbit and that's what's happening, the Earth will pull you in, and that's what's happening to the space station coming in uncontrolled which means they don't exactly where it's going to land. That's good to know. Looking at the Earth, when I looked at it from space I realized there's a at lot of water down there. The Earth is 70% water so the chances it will hit land is unlikely. Plus, the chance it's going to hit land where people are or buildings are is even less likely so it will be coming in. Parts of it will hit the Earth, not much. Most will burn up in re-entry. Some will make it through the atmosphere and strike the Earth. The chance of anyone getting hit is very remote. This is a substantial sized space station. Why is this happening? Why isn't it just orbiting and staying in space? It's a good question. Yeah, there's still a little bit of drag. In other words, when we move through the air, the air gives us drag. If you think like moving through the water versus moving through the air, moving through the water is harder because there's more drag. Moving through the air there is less drag and in space there's even less but there still is a little bit even though you're far away from the planet. There still is a little drag. There's less of it up there so it doesn't slow you down much but over the years going as fast as something like this space station does that drag builds up. Starts to slow you down and as you slow down, gravity starts to pull you closer and closer to the Earth. And that's exactly what's happening with this object. Mike, thank you. Bottom line -- Are you feeling any better. I'm going to worry about other things like the Powerball. Worry about other things. I can understand why people are concerned but I think we'll be okay. If we're not, they'll find you. Mike, thank you.
This transcript has been automatically generated and may not be 100% accurate.