prep 3 , unit 3 , part 1

The number of galaxies in the universe is about .......... Million

• 10 000

• 100 000

• 20 000

• 200 000

The building units of the universe are

• planets

• stars

• galaxies

• moons

Galaxies gather in groups known as

• galaxies clusters

• ancestral galaxies

• galaxy centre

• Venus

............... is the star of our solar system.

• Moon

• GGalaxy

• SSun

• TThe earth

The Sun and the surrounding planets revolve around the

• Earth

• Moon

• GGalaxy centre

• the solar system

The solar system consists of the Sun and

• nine planets

• eight planets

• 200 000 galaxies

• the solar system

The solar system is located in one of the arms of the Milky Way galaxy.

• spiral

• cylindrical

• straight

• spherical

The Sun takes about ...... to complete one rotation around the centre of the galaxy.

• 220 thousand years

• 220 million years

• 202 million years

• 202 years

Astronomers measure the distances between stars with light year, because the stars

• generate great amounts of light

• seem as small light dots in the sky

• are millions of kilometres away from each other

• generate great amount of heat

The scientists believe that the universe emerged from a massive explosion and it is in

• continues contraction

• contraction then expansion

• expansion then contraction

• continues expansion