“If you're going to lead a space frontier, it has to be government; it'll never be private enterprise. Because the space frontier is dangerous, and it's expensive, and it has unquantified risks. And under those conditions, you cannot establish a capital-market evaluation of that enterprise. You can't get investors.”

American astrophysicist and science communicator of the late 20th and early 21st centuries, he bridges complex cosmic concepts for broad audiences. His work on the Cosmos television series and public lectures makes astronomy accessible, while his writings and media appearances champion evidence-based reasoning and critical thinking.