
The largest planet in the Solar System, often used as a reference for exoplanet size and mass.Jupiter is the largest planet in our Solar System, a gas giant with a mass more than twice that of all other planets combined. Its sheer size and gravitational influence make it a natural reference point for astronomers studying exoplanets: when a distant world is described as a 'hot Jupiter' or a 'super-Jupiter,' it is being compared to this familiar giant. Jupiter's powerful gravity also shapes the architecture of the Solar System, deflecting comets and asteroids and influencing the orbits of neighboring planets.
Known since antiquity, Jupiter was first studied in detail by Galileo Galilei in 1610, when he discovered its four largest moons, providing early evidence for the Copernican model. The Great Red Spot was observed as early as the 17th century, though its continuous observation began in the 19th century.
Jupiter is composed primarily of hydrogen and helium, with no solid surface. Beneath its visible cloud tops, pressure and temperature rise until hydrogen transitions into a metallic state, where it conducts electricity and generates the planet's immense magnetic field. This field, the strongest of any planet, traps charged particles and produces intense radio emissions. The planet's rapid rotation—a day lasts under ten hours—drives its banded atmosphere and the Great Red Spot, a storm larger than Earth that has persisted for centuries.
Jupiter serves as a gravitational slingshot for spacecraft heading to the outer Solar System, and its moons are prime targets in the search for habitable environments beyond Earth.
Jupiter's magnetic field is so large that it extends past Saturn's orbit, making it the largest structure in the Solar System after the heliosphere.



























