When provoked, the itsy-bitsy invertebrates known as tardigrades can suspend their metabolism. In that state, they can survive temperatures of... 73 K for days on end, making them hardy enough to endure being stranded on Neptune. So the next time you need space travelers with the right stuff, you might want to choose yeast and tardigrades, and leave your astronauts, cosmonauts, and taikonauts at home.

These are two different exercises. One of them is, "You don't know and I know, so just shut up and listen," and the other one is, you're curious and you're learning, and I have a way where you can learn this so you'll know it as well. And when you know it, and know why you know it, then you don't have to reference me ever again because you take ownership of the knowledge, and you can then share it with someone else.

Down there between our legs, it's like an entertainment complex in the middle of a sewage system. Who designed that?

I lose sleep at night wondering whether we are intelligent enough to figure out the universe. I don't know.

We in astrophysics we think of the universe all the time. So to us, Earth is just another planet. From a distance, it's a speck. And I'm convinced that if everyone had a cosmic perspective you wouldn't have legions of armies waging war on other people because someone would say, "Stop, look at the universe."

One of the reasons we're here, that we exist at all, is that Earth, cosmically speaking, is in a relatively peaceful place: orbiting our Sun in a near perfect circle.

Some molecules - ammonia, carbon dioxide, water - show up everywhere in the universe, whether life is present or not. But others pop up especially in the presence of life itself. Among the biomarkers in Earth's atmosphere are ozone-destroying chlorofluorocarbons from aerosol sprays, vapor from mineral solvents, escaped coolants from refrigerators and air conditioners, and smog from the burning of fossil fuels. No other way to read that list: sure signs of the absence of intelligence.