Solar System

Jupiter

Gas giant · The giant of the system · Known since antiquity

The largest planet by far, Jupiter is a ball of hydrogen and helium with a centuries-old storm — the Great Red Spot — wider than Earth.

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Texture: Solar System Scope (CC BY 4.0)

Key facts

Distance from Sun 5.20AU 778.5 million km
Radius 69,911km 11.0× Earth
Mean temperature −110°C cloud-top average

Time & motion

A day (one spin) 9.9 hours The fastest spin of any planet, despite its size.
A year (one orbit) 11.9 Earth years Jupiter takes almost 12 years to circle the Sun once.
Surface gravity vs Earth
23.1 m/s² 2.36 g
0Earth = 1 g2.5×

Mass & physical characteristics

Mass 1.90 × 10²⁷kg 317.8× Earth
Density 1.33g/cm³ Water = 1.0 g/cm³
Escape velocity 59.5km/s Speed to break free
Orbital velocity 13.1km/s Speed around the Sun
Axial tilt 3.1° Nearly upright, so Jupiter has little seasonal change.

Atmosphere & magnetosphere

Atmosphere

About 90% hydrogen and 10% helium, with traces of methane and ammonia. No solid surface — banded clouds deepen into liquid metallic hydrogen.

Magnetic field

The strongest planetary magnetic field, with intense radiation belts.

Moons & rings

Known moons 115 115 confirmed moons, including the four large Galilean moons.
Notable moons
IoEuropaGanymedeCallisto

Rings

A faint dust system — a main ring, an inner halo, and two wide gossamer rings.

Make-up

Composition

Mostly hydrogen and helium; no solid surface. Faint ring system.

Notable features

  • The Great Red Spot — a storm wider than Earth that has raged for centuries.

Fun facts

  • Jupiter is more than twice the mass of all the other planets combined.
  • It has no solid surface — just deepening layers of hydrogen and helium.
  • The Great Red Spot is a storm wider than Earth that has been observed for over 300 years.
  • Jupiter spins fastest of any planet — a day there lasts under 10 hours.
  • Its largest moon, Ganymede, is bigger than the planet Mercury.

Exploration

Voyager 1 & 2 1979 Revealed the rings and volcanically active Io.
Galileo 1995–2003 First orbiter; dropped a probe into the atmosphere.
Juno 2016– Mapping the interior, gravity and magnetic field.