Look up at the night sky. Every distant world, every wisp of cosmic gas, and the very iron coursing through your blood are part of a 4.5-billion-year-old story. We are star stuff contemplating the stars—conscious stardust striving to map the very cloud from which we emerged. Welcome to Fall in Cosmos, where we explore the vast architecture of our solar system.

[THE STORY] Our celestial neighborhood did not begin in serene calm, but in violent, rotating chaos.

• The Foundation: Roughly 4.5 billion years ago, a massive cloud of interstellar dust and gas collapsed under its own gravity to form the protoplanetary disk, with our Sun igniting at the center.
• The Inner Furnace: Near the newborn Sun, only rocky materials could withstand the heat, forging the four inner terrestrial wo ...