Astronomy
Space Planets: Worlds Beyond Earth
Quick fact
The first confirmed exoplanet orbiting a Sun-like star was discovered in 1995. Since then, thousands have been found, some in the habitable zone where liquid water could exist.
Why this is interesting
You've heard of planets in our solar system, but did you know that almost every star in the night sky might have its own family of planets? What are these distant worlds like?
Read the full explanation
Understanding Space Planets: Worlds Beyond Earth
A space planet, or exoplanet, is any planet outside our solar system. Just like the planets around our Sun, exoplanets orbit a star. They are detected mainly by two methods: the transit method, where the planet passes in front of its star and dims it slightly, and the radial velocity method, which detects the star's tiny wobble due to the planet's gravity. Exoplanets range from gas giants larger than Jupiter to rocky worlds smaller than Earth. Some orbit very close to their star (hot Jupiters), while others are in the habitable zone, where conditions might allow liquid water.
A deeper explanation
Exoplanets form from the same swirling disk of gas and dust that creates their star. Over millions of years, particles collide and stick, building up to form planetesimals and eventually planets. The diversity of exoplanets challenges our models of planet formation—some large planets orbit very close to their star, suggesting they migrated inward. Studying exoplanets helps us understand why our own solar system is the way it is and whether Earth-like worlds are common. Missions like Kepler and TESS have revolutionized the field, cataloging thousands of candidates. The ultimate goal is to find a truly Earth-like planet and study its atmosphere for signs of life.