Science & Space
Earth
The third planet from the Sun and the only known world to support life.
Earth is a rocky, layered planet orbiting the Sun at an average distance of one astronomical unit (≈150 million km / 93 million miles).
About 71% of its surface is covered by a global ocean and its atmosphere and magnetic field combine with geological activity to make Earth habitable for a wide diversity of life.
Quick facts
- Earth is the third planet from the Sun and the fifth-largest planet in the Solar System. (NASA).
- Earth orbits the Sun at an average distance of about 1 astronomical unit — ~150 million km (≈93 million miles) — and sunlight takes about 8.35 minutes to reach it. (NASA).
- About 71% of Earth’s surface is covered by the global ocean; Earth is the only known astronomical object to harbor life. (NASA; National Geographic).
- Earth is layered — crust, mantle, liquid outer core and solid inner core — and its inner core is extremely hot; core processes help generate Earth’s magnetic field. (AMNH; NASA).
- Earth’s atmosphere is roughly 78% nitrogen and 21% oxygen (with ~1% other gases); the atmosphere and magnetosphere shield life from much harmful radiation and most meteoroids. (NASA).
A surprising fact
Earth’s inner core is a solid ball of mainly iron and nickel that is estimated to be as hot as — or hotter than — the surface of the Sun. (AMNH).
