Milky Way estimated to host billions of planets

Astronomers estimate that the Milky Way galaxy, which contains roughly 100 billion to 400 billion stars, likely hosts a comparable number of planets. Data from the European Space Agency's Gaia satellite, together with exoplanet surveys from NASA's Kepler (launched in 2009), TESS and the James Webb Space Telescope, show that on average each star in the galaxy has at least one planet orbiting it. This suggests that the Milky Way could contain hundreds of billions, possibly trillions, of planets.

Before the 1990s, no planets outside the Solar System had been confirmed. The Kepler mission demonstrated that planets are a common by‑product of star formation, reshaping our view of the cosmos and indicating that planetary systems are the rule rather than the exception.