If we lived light years from Earth, how would we know there’s life here? Let’s take a look at the search for extraterrestrial life on habitable exoplanets, and discover what biosignatures would show someone else that we’re here.
I went to NASA in Houston to talk to astronaut Don Pettit.
Why is ice slippery? It's a more complicated answer than it seems!
Recycling is broken. Here's how we can fix it.
