Download The Solar System - Oxford University Press

Leggi e ascolta.
The Solar System
There are four main parts to the Solar System:
• The Sun is at the centre of the Solar System.
• Planets go around the Sun.
• Moons go around planets.
• Comets and asteroids go around the Sun.
The Sun
The Sun is at the centre of the Solar System. It’s more than
a million kilometres in diameter and it’s about 4.5 billion
years old. The temperature on the Sun is more than 5,000 °C.
Light from the Sun takes about eight minutes to get to Earth.
Planets
There are eight main planets in the Solar System and
they all orbit the Sun. The first four planets are made of
rock, the others, for example Jupiter and Saturn, are made of
gas and they are much bigger. The planets furthest from the
Sun take longer to go around it and they are usually colder,
too. In 1930, a ninth planet was discovered – Pluto. However,
scientists now say it’s too small to be a true planet and it is
now a ‘dwarf planet’.
Moons
All the planets, except Mercury and Venus, have got
moons. Some moons are very big. For example, Saturn’s
moon, Titan, is bigger than the planet Mercury. It’s impossible
to land on Saturn, because it’s made of gas. But its moon,
Titan, is made of rock and ice. In 2004, the mission Huygens
landed on Titan and took photographs of Saturn and its
moon. It doesn’t look like a great place for a holiday and it’s
very cold!
High Five Level 3 . CLIL Science p. 218
© Oxford University Press PHOTOCOPIABLE
Comets and Asteroids
Comets are small balls of ice and rock. When they move
nearer to the Sun’s heat, the ice melts and turns to water and
gas. This gas becomes the comet’s tail. These tails can be
millions of kilometres long and they are visible from Earth.
When the comet moves away from the Sun, it gets colder and
it loses its tail. Halley’s Comet is the most famous comet. We
can see it every 75 years. The last time it was seen was in 1986
and its next visit will be in 2061.
Thousands of asteroids orbit the Sun. Asteroids are made
of rock and they never have a tail. Sometimes asteroids hit
the Earth. Another asteroid hit Earth 66 million years ago
and it is believed that the impact caused the extinction of the
dinosaurs. Another asteroid hit the Earth in 2013. It was about
20 metres in diameter and disintegrated over the Russian
region of Chelyabinsk. Nobody died, but a lot of people
were hurt.
High Five Level 3 . CLIL Science p. 218
© Oxford University Press PHOTOCOPIABLE