How many planets can you name? Seven? Eight? You don’t have to stop after Uranus and Neptune. Scientists estimate that there could be billions of planets that orbit other stars, just like Earth orbits the Sun.
Scientists call these distant planets extrasolar planets, or exoplanets for short. “Extrasolar” just means ”outside the solar system.” Humans have observed the stars for thousands of years, but the first exoplanet wasn’t confirmed until 1991. Since then, scientists have discovered thousands more.