Jupiter, the Planet with a Solar System of Its Own

Why We Study Jupiter

Named after the king of the gods in Roman mythology, Jupiter is a stunning sight to behold. Its red, orange, and yellow swirls, spots, and bands are visible even from small backyard telescopes. Astronomers have observed the planet’s Great Red Spot, a raging storm larger than Earth, for at least 200 years.

Jupiter was the first planet in our solar system to form. It was probably born much closer to the Sun before migrating to its current position about 4 billion years ago, scattering asteroids and comets with its gravity in the process. Some of those asteroids and comets slammed into early Earth, possibly bringing water here in the process—the key ingredient for life as we know it.

Many exoplanets—planets in other solar systems—we have discovered are Jupiter-like worlds close to their stars, reinforcing the idea that our own solar system’s large planets have moved from their original positions. By studying Jupiter and comparing it to similar exoplanets, we learn how solar systems evolve and the possibilities for life elsewhere.

Jupiter has a faint ring system and at least 79 moons, 4 of which are active, planet-like worlds ranging in size from just smaller than Earth’s Moon to larger than Mercury. All but Io likely have liquid-water oceans under their surfaces, making them possible havens for life as we know it. Europa’s ocean in particular may be the most biologically promising environment beyond Earth for life. Jupiter challenges our perceptions about where life can exist in the universe.