What does it take to revise a cold, hard science fact? This month’s Sparks podcast explores that question in the context of “The Hunt for Vulcan” by Thomas Levenson. Levenson’s book chronicles the 19th-century search for a planet that astronomers believed had to exist to explain a wobble in Mercury’s orbit. Without that planet — known as Vulcan — Isaac Newton’s gravitational theories didn’t quite work. What scientists didn’t consider was that those vaunted Newtonian laws might not fully explain the universe. And then Albert Einstein came to the rescue.

In the podcast, which runs in FiveThirtyEight’s What’s The Point feed, senior science writer Maggie Koerth-Baker, lead science writer Christie Aschwanden and senior editor Blythe Terrell talk through how science ideas evolve over time — and how challenging that process can be.

The second part of this month’s podcast features Christie interviewing Levenson about the book. You can listen below:

And if you want to read along for next month, we’ll be talking about that most delightful of senses, taste, with “Flavor” by Bob Holmes. Join us!