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2. The Earth in the Universe
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3.3.
The movements of the planets
All the bodies in the Universe are continuously moving. The planets in our Solar
System move in two different ways: revolution and rotation.
The orbits of the planets in the Solar System are elliptical and are on approximately
the same plane. The planets orbit the Sun in an anticlockwise direction.
Revolution
is the movement of the planets around the Sun. The period of
time that a planet takes to complete one revolution around the Sun is called
a
year
.
Revolution
Apply
14.
Which planets take longer to orbit the Sun: the inner planets or outer
planets?
Rotation
is the movement a body makes on its own axis. The period of time
that a planet takes to complete one rotation is called a
day
.
Key concepts
❚
The Solar System is located
in the Orion Arm in the Milky
Way.
❚
The Solar System consists
of the Sun and a group of
bodies that orbit around it:
the planets, dwarf planets,
satellites and comets.
❚
Revolution is the movement
that planets and other bodies
make around the Sun.
❚
Rotation is the movement
that planets and other bodies
make on their own axis.
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orbital plane
:
the plane on which
a body is orbiting
Understand
15.
Listen and say true or
false. Correct the false
sentences.
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Axis of rotation of the planets
Apart from Uranus, which rotates on a horizontal axis, planets rotate on an axis
which is perpendicular to their orbital plane
5
. Like revolution, the rotation of most
planets is in an anticlockwise direction (except for Venus and Uranus).
