Proxima Centauri is the closest star to our solar system, just 4.25 light years away, yet it is completely invisible to the naked eye. This episode explores why a star sitting on our galactic front porch went undiscovered until Robert Innes spotted it in 1915, and what makes this M5.5 red dwarf so strange: only 12.5 percent of the Sun’s mass, 33 times denser, burning at roughly 3,000 Kelvin, and radiating more than 85 percent of its energy as infrared light.

The conversation digs into the physics of a fully convective star that stirs its own fuel and could burn for four trillion years, the violent flare activity that made it 68 times brighter in 2016, and the planets caught in the crossfire, including the Earth-sized Proxima b discovered by the Pale Red Dot project. It also traces Proxima’s 550,000-year orbit around Alpha Centauri A and B, its future as a lone wanderer, and why our nearest neighbor is only a temporary one.

• Why an M-class star 268,550 AU away has an apparent magnitude of 11.13, far below the naked-eye limit of about 6
• How full convection lets Proxima avoid the helium-ash problem that will turn our Sun into a red giant
• Why a star with 0.16 percent of the Sun’s visual luminosity produces comparable X-ray output and a 3.5 million Kelvin corona
• What the radial velocity wobble method revealed about Proxima b, its 11.2-day orbit, and the debate over whether a habitable zone means habitable
• Why Proxima has only been our closest star for 32,000 years, will peak at 3.11 light years in about 26,700 years, and why Voyager 1 would need 73,000 years to reach it