rocky
Earth
Our home in the cosmos
Earth is the third planet from the Sun and the only known place where life has taken hold. Its oceans, atmosphere, and magnetic field combine to protect a rich biosphere. Earth is our reference point for everything we discover about other worlds.
Key facts
- Diameter
- 12,756 km
- Radius
- 6,371 km
- Mass
- 5.972e+24 kg
- Gravity (Earth = 1)
- 1.000
- Density
- 5.514 g/cm³
- Distance from Sun
- 149,600,000 km
- Orbital period
- 365.25 Earth days
- Rotation period
- 23.93 hours
- Average temperature
- 15°C
- Known moons
- 1
Values are approximate and based on cited sources.
Atmosphere
- Nitrogen
- Oxygen
- Argon
- Carbon dioxide
Surface
Continents, oceans, ice caps, and diverse ecosystems shaped by tectonics and life.
Internal structure
A solid inner core, liquid outer core, mantle, and thin crust.
Moons
The Moon
The only celestial body beyond Earth visited by humans.
Exploration missions
- • Apollo program
- • International Space Station
- • Landsat
Sources
- NASA Science — Earth— last verified 2026-01-15