Information AgeTechnology Reusable rockets 2015Major SpaceX lands an orbital-class booster, cutting launch costs. ▲ MattersSaveShareTrace roots Longest chain: The Big Bang → First stars ignite → Supernovae seed heavy elements → The Sun forms → Earth forms → First oceans → First life → Photosynthesis evolves → Great Oxidation Event → Complex cells (eukaryotes) → Multicellular life → First animals → Cambrian Explosion → First vertebrates → Jawed fish → Fish walk onto land → The amniotic egg → The Great Dying → Dinosaurs appear → Asteroid ends the dinosaurs → Early primates → Apes split from monkeys → Human line splits from chimpanzees → Walking upright → First stone tools → Genus Homo appears → Homo erectus → Control of fire → Habitual fire and cooking → Homo sapiens appears → Complex language → Natufian villages → Oldest known bread → Agriculture begins → Irrigation → Uruk and the first cities → Cylinder seals → Writing (cuneiform) → Babylonian mathematics → Babylonian astronomical diaries → Thales and natural philosophy → Trial and death of Socrates → Plato's Academy → Aristotle's Lyceum → Alexander's conquests → Alexandria founded → Library of Alexandria → House of Wisdom → Al-Khwarizmi and algebra → Fibonacci's Liber Abaci → Bills of exchange → Medici Bank → Double-entry bookkeeping → Muscovy Company → English East India Company → Seven Years' War → American Revolution → Declaration of Independence → French Revolution → Revolutions of 1848 → German unification → World War I → Treaty of Versailles → Great Depression → Nazis take power → World War II → Atomic bomb → Cold War begins → Sputnik → First human in space → Moon landing → Reusable rockets Community notesLoading notes… Learn more ranked by votesBookEric BergerLiftoff: Elon Musk and the Desperate Early Days That Launched SpaceX ↗Editor's pickVideoSearch on YouTubeFalcon 9 first booster landing ↗Editor's pick