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Earth – Planet · Our home
Image: EUMETSAT · Attribution
🪐 Planets · Home Base

Earth

Planet · Our home

Earth is the third planet from the Sun and the only place in the universe where we know life exists. About 71% of its surface is covered by liquid water, and a thin blanket of air protects us from the cold and radiation of space.

  • 0 km awayYou are standing on it right now!
  • 12,742 kmDiameter
  • 4.54 billion yearsAge
🔭 Find it in the sky

Take a closer look

A planet in layers

Earth is built in layers: a thin rocky crust, a thick hot mantle that flows very slowly, and a core of iron and nickel. Compared with the whole planet, the crust is thinner than the skin on an apple, and the solid inner core is about as hot as the surface of the Sun.

An invisible shield

Deep down, liquid iron swirls around Earth’s inner core and turns the planet into a giant magnet. This magnetic field makes your compass point north and pushes away most of the charged particles streaming from the Sun. The few that slip in near the poles make the sky glow as the northern and southern lights.

Air made by life

The air you breathe is about 78% nitrogen and 21% oxygen, and most of that oxygen was made by living things. Tiny ocean microbes began filling the sky with it more than 2 billion years ago. Today, microscopic ocean plankton still make roughly half of the oxygen on Earth.

How we found out

  1. ~240 BC

    Eratosthenes measures the size of Earth by comparing shadows in Syene and Alexandria, Egypt.

  2. 499 AD

    The Indian astronomer Aryabhata writes that the stars only seem to move because Earth spins.

  3. 1543

    Nicolaus Copernicus publishes his idea that Earth goes around the Sun, not the other way around.

  4. 1968

    Apollo 8 astronauts photograph “Earthrise” – Earth rising over the Moon.

  5. 1990

    Voyager 1 looks back from about 6 billion km away and sees Earth as a “Pale Blue Dot”.

🤔 Something to wonder about

If Earth is spinning so fast, why don’t we feel it?

See it yourself

Look down! You’re standing on it. In the Sky Finder, Earth is always “below your feet”.

Got it?

Mark Earth as explored to earn 10 XP.