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THE MOON
Soon after Earth formed, it was
hit by a planet-sized asteroid
that completely disintegrated.
Most of its heavy metallic core
melted into Earth, but the
lighter rocky fragments drifted
into orbit and eventually fused
to form the Moon.ON THE SURFACE
Movement in the thick, hot
mantle has made the thin, cool
crust crack into several huge plates.
The boundaries of these plates are
marked by earthquake zones dotted
with volcanoes, and mountain ridges
pushed up where moving plates collide.(^7) LAND SURFACE
Exposed to frost, wind, rain, and hot
sunlight, the rocks at the land surface
are broken down by weathering and
erosion. This releases minerals that
are vital to plants and other life.
(^8) OCEANS
The low-lying basins between the
continents are filled with water, to an
average depth of 3.7 km (2.3 miles).
Most of the water erupted from
volcanoes as water vapour early in
Earth’s history.
(^9) WEATHER SYSTEMS
The heat of the Sun makes water
evaporate from the oceans and rise
into the lower atmosphere. The water
forms swirling masses of cloud that
spill rain onto the continents,
allowing life to exist on land.
(^10) ATMOSPHERE
Earth’s mass gives it enough gravity
to retain an atmosphere of nitrogen,
oxygen, and other gases including
carbon dioxide. This keeps Earth
warm at night, and shields it from
dangerous radiation.
More than 70 per cent
of Earth’s surface is
covered by ocean water
The Red Sea is a
spreading rift in
Earth’s crust that
will widen into
an ocean
Huge impact craters
have filled with dark
lava erupted from
Volcanoes
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