12 Space Telescope Discoveries That Reshaped Our Understanding of the Universe

2. Exoplanets - Worlds Beyond Our Solar System

The Kepler Space Telescope revolutionized our understanding of planetary systems by discovering thousands of exoplanets orbiting distant stars, proving that our solar system is far from unique in the cosmic landscape. Launched in 2009, Kepler used the transit method to detect planets by measuring the tiny dimming of starlight as planets passed in front of their host stars, revealing an astonishing diversity of planetary types and configurations previously unimaginable. Among its most significant discoveries were "super-Earths" – planets larger than Earth but smaller than Neptune – which appear to be the most common type of planet in our galaxy, despite having no analog in our own solar system. Kepler also identified planets orbiting in the habitable zones of their stars, where liquid water could potentially exist on their surfaces, dramatically expanding our conception of where life might arise in the universe. The telescope's observations revealed that planetary systems come in configurations wildly different from our own, including planets with orbital periods of just hours, multiple-planet systems packed more tightly than Mercury's orbit around the Sun, and planets orbiting binary star systems like the fictional Tatooine from Star Wars. These discoveries have fundamentally altered our understanding of planetary formation and evolution, suggesting that the processes that created our solar system may be just one of many possible pathways to world-building in the cosmos.