One of the fan questions in last night’s COSMOS panel (live streamed on Tuesday night ahead of the TV première of COSMOS 2104 on Sunday) was about the panel member’s favorite fact about science. It’s such a huge question that it would be hard to answer on the spot. My answer to this (after some thought), is that science is weird beyond what we can imagine and yet it is everyday, and all around us. Ever think about why, when you put your hand on a tabletop your hand does not just slip right though, although supposedly the atoms both are made of are mostly empty space? It’s because the electrons in the tightly packed atoms of your hand repel the electrons in the tightly packed atoms that make up the table—what you feel is the result of electromagnetic repulsion. I know I’m a big geek but when I first read about that I started tapping my hand against the table and felt slightly giddy with fascination. (NOTE: My understanding of how that actually works is not precise. Feel free to send corrections my way if I have described it incorrectly.)

Then there is that favorite fact that I learned first from my astronomy prof at UofL, and then heard again from Carl Sagan, that we are made of “starstuff.” It’s a bit of a romantic notion since people have long mystified the stars, but there is such an incredible depth to the idea that I never entirely get used to it. It encompasses the Big Bang and the formation of the simplest atoms of hydrogen. Those hydrogen atoms then clump together from gravity (since the expansion of matter from the Big Bang was not entirely uniform) into big balls of gas so massive that the pressure of gravity at their centers started smashing those hydrogen atoms together so hard that they fused together to make helium—producing vast amounts of heat and light in the process. Then the new star took billions of years to burn up all its hydrogen, so it then starts fusing the hydrogen into carbon—the basic elemental building block for life—and then carbon into iron (assuming it was a really massive star) and then exploded as a supernova since a star can’t sustain itself on iron fusion. And the heat and pressure from the supernova (which sometimes outshine their entire galaxy!) finishes the job and fuses the elements that are heavier than iron. *Deep breath, ‘cause that was a mouthful.* The supernova blasted those atoms out into space where they eventually formed dust clouds and new stars and solar systems, and…us. The wonder of massive stars far away and long, long ago, and the strangeness of atoms and nuclear processes, time scales beyond our innate comprehension…that’s what we’re made of. When you really get it, doesn’t it make your heart pound?

For a more technical and in-depth, yet simple and concise, explanation of the life cycle of stars and the building of elements, visit

You can also view the panel discussion for Cosmos: A Spacetime Odyssey online at COSMOS: A SPACETIME ODYSSEY Live Event.