2.13 Understanding our Universe8 April 2023

What is this

image?

Key terms

• Orbit: the path of an object moving through space such as the path of the Earth as it goes around the sun

The Solar System• The Solar System consists of the Sun and

all the objects that are attracted to the Sun by gravity

• These include the eight planets and other objects such as asteroids and meteroids

• The Sun is the brightest star and is the centre of the Solar System

• Because the Sun is so huge, its gravity holds the planets in their orbits around it

Objects in the night sky (1)• If you look at a clear night sky, you will see that it is filled

with various objects• With the naked eye you can see the light of thousands of

stars, which seem to be arranged in patterns, called constellations

• Because the Earth rotates, the stars rise and set like the Sun

• You will also see planets• These do not shine their own light but reflect light from

other sources• Because they are close to the Earth, they shine brightly

and do not twinkle

Objects in the night sky (2)

• If you are lucky you may see an object with a bright tail• This is likely to be a comet, which are made from rock, dry ice and

frozen gases such as CO2 and CH4.They come from outside our Solar System

• You may also see ‘shooting stars’ which are meteors, these are bits of dust and rock which enter the Earth’s atmosphere

• Astronomers have also discovered hundreds of stony objects called asteroids, which also orbit the Sun

• The Earth’s moon is clearly visible and its appearance changes through the month as it orbits the Earth

• With a good telescope you can see that other planets have moons. Jupiter has 63 moons, one of which has volcanoes.

Origin of the Solar System• Astronomers believe that the Solar System was formed when

clouds of gas and dust collided• Eventually our sun was formed, together with other objects

such as planets• Asteroids and meteoroids are believed to be remains of that

cloud.• Geologists have investigated meteorites and estimate they

are 4.5 billion years old• The effect of meteoroids and asteroids that hit the surface of

the moon can clearly be seen even with the naked eye• Some astrophysicists believe that the Earth was formed by

collisions of asteroids and meteoroids

Assessment Activity• You are an astronomer working for an

observatory. You are invited to a primary school to describe our Solar System to young children– Working in groups of three, construct a model of

the solar system, showing the distances of the eight planets from the Sun

– In your groups, investigate the theory described above of how the Solar System was formed. Present your results in the form of a poster