This week, we begin a new month-long journey into one of the most awe-inspiring subjects in astronomy: Galaxies.

We start close to home by exploring our own galaxy, the Milky Way, and asking a deceptively simple question: where does a galaxy actually end? Along the way, we’ll explore spiral arms, dark matter, supermassive black holes, the hidden structure of our galactic halo, and the faint ghostly glow of Integrated Flux Nebula, dust clouds illuminated by the combined light of billions of stars.

We’ll also discover why our solar system doesn’t align with the Milky Way the way you might expect, how astronomers mapped our galaxy from the inside using radio waves, and what the night sky might look like if the Milky Way simply vanished.

Later in the episode: I report on a backyard observation of Amazon’s recent Leo satellite launch ...