Page 17 - Super Earth Encyclopedia

Extra-thick slabs of
rocky crust floating on Earth’s gravity retains EARLY EARTH
the dense mantle form the mixture of gases
the continents. we call air, forming Earth was formed by the force of gravity,
the atmosphere. which makes objects floating in space attract
The rock of the each other. Gravity increases with mass,
upper mantle is solid enabling a ball of dust to grow into a planet.
but quite soft, so it can
flow like warm caramel.

ACCRETION
As fragments of space rock collided due to
gravity, the impact generated heat that partly
melted these space rocks and welded them
together. This process is called accretion.

The cool shell of the upper
mantle forms the oceanic
crust—the bedrock of
ocean floors.

Intense pressure keeps
the lower mantle solid,
despite being very hot.
The liquid outer core is mainly
molten iron and nickel, with
the rest made up of sulfur
and other elements.
At the heart of the planet lies MELTDOWN
the metallic inner core—a ball As Earth grew bigger, the heat built up by the
of solid iron and nickel. impact of so much space rock made it melt.
In places, the oceanic crust Most of the heavy iron sank to the center
is dragged into the mantle, to form the planet’s core.
where it is melted and recycled.

“The temperature

of Earth’s inner

core is about 10,000°F

(5,500°C)—just as UNIQUE EARTH

AIR AND WATER
hot as the surface Massive volcanic eruptions during the planet’s
first 500 million years released water vapor
of the Sun.” and other gases, which formed the oceans and 15
early atmosphere.

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