DK - WOW! The Visual Encyclopedia of Everything

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FORMATION OF THE MOONEarth formed as ever-larger lumps of unused material collided and joined together. Young Earth was hit by a Mars-sized asteroid. Molten rock from the collision splashed into space. This formed a ring of rubble around Earth which clumped to form a large sphere – Earth’s Moon.

10

BILLION YEARS AGO

4.6

BILLION YEARS AGO

TODAY

4.5

BILLION YEARS AGO

Rock from

Earth’s mantle is thrown out as the asteroid hits the planet

YOUNG MILKY WAY

The Milky Way galaxy, the galaxy

we live in, formed at the same time as

the other galaxies. Not all of today’s Milky

Way stars existed at that time. Since its beginning,

the galaxy has produced stars that shine brightly for millions or billions of years, but that die eventually.

Their remains produce a new generation of stars.

HOME PLANET

Earth, the third rock planet

from the Sun, is the only place

in the Universe where life is

known to exist. Life started in its

oceans at least 3.7 billion years

ago. Bacteria-like cells evolved into

sea creatures, then land-based plants,

and animals. Humans first walked on Earth about 1 million years ago.

BIRTH OF THE SOLAR SYSTEMThe Solar System formed from a cloud of

gas and dust within the disc of the Milky

Way galaxy. The spinning cloud, known as

the solar nebula, collapsed in on itself under the force of gravity. It first formed a central

sphere – the young Sun – and then the

unused material surrounding the Sun formed

the planets, moons, asteroids, and comets.

Water – in the oceans, lakes, atmosphere, and ice caps – has been a key factor in the developement of life on Earth

128_129_Universe.indd 129 03/01/19 12:10 PM