On a freezing February morning in 2013, a second, impossibly bright sun streaked across the Russian sky, followed by a blinding flash and minutes of eerie silence. Then an invisible wall of energy shattered a city. Every detail of that morning was entirely real.

This episode unpacks the staggering physics of the Chelyabinsk meteor, an 18-meter, 10,000-ton rock that exploded with the force of about 30 Hiroshima bombs. It is a story about how our atmosphere protects us, the human heroics it inspired, and the sobering realization of our vulnerability to the cosmos.

• Why the meteor was invisible to telescopes: its radiant sat in the glare of the rising sun
• Ram pressure and the air burst about 30 kilometers up that spared the city below
• The deadly silent gap that drew people to windows just before the shockwave blew out ...