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12.1 The Solar System

This diagram is a
representation of
most of our Solar

System. What are the
textbooks nis edu kz
main similarities and
differences between

the celestial objects
within it?

DID YOU KNOW?

According to astronomers
and the measurements made
by telescopes (scientific
instruments that observe
light from distant objects), How is the Solar System arranged?
the nearest star to our Solar The Solar System consists of many different types of celestial objects
System, Proxima Centauri, is such as stars, the planets and their satellites and other types of
4.2 light-years away from us objects that have a variety of different shapes, sizes and trajectories,
(1 light-year is about 9 trillion including asteroids and comets.
km). Even with the latest
technology we would not be Our star: the Sun
able to travel that far. There The Sun is at the centre of our Solar System. The Sun is a star – just one
are many other solar systems of over a million stars that make up our galaxy. It is the largest celestial
around our galaxy, each with object in our Solar System. Its mass equals about 98% of the mass of
different planets orbiting the whole Solar System. As we learnt in Unit 5, this means the Sun
different stars. exerts a large gravitational force on all other masses. This is one of the
reasons why all objects in our Solar System are attracted to it and rotate
around it.
DID YOU KNOW?

All planets, besides Venus The planets
and Uranus, rotate east to There are many objects orbiting the Sun, and scientists have classified
west while completing their them in different ways. Eight of these objects are planets. The planets
motion. Uranus rotates lying of the Solar System, in order from the Sun, are: Mercury, Venus, Earth,
almost on its side, as the Mars, Jupiter, Saturn, Uranus and Neptune. Uranus and Neptune
inclination of its axis is almost can only be seen using a telescope, while all the other planets can be
90°. We can imagine planets seen by the naked eye on a clear and dark night.
as spinning tops rotating
in one direction, Venus as a ACT Find out the 3 main conditions set by the International
top rotating in the opposite Astronomical Union for an object to be considered a planet.
direction and Uranus as a
‘barrel’ rolling along its orbit.

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