The building units of the universe are .............

• planets

• stars

• galaxies

• moons

The universe contains ............

• galaxies and stars

• planets and moons

• living organisms

• all of the previous

Galaxies are formed of groups of .................

• moons

• constellations

• stars

• planets

Galaxies gather in groups known as ....................

• galaxies clusters

• solar system

• ancestral galaxies

• planets

.................. are located in the spiral arms of Milky Way Galaxy.

• old stars

• moons

• small stars

• (a) and (c)

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

• moon

• galaxy

• The Earth

• The Sun

The solar system consists of the Sun and ............... planets rotate around the Sun.

• nine

• eight

• six

• seven

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

• spiral

• oval

• straight

• circular

The light year is .................

• the distance covered with light in one year.

• the light speed in km/sec

• the time consumed by light to cover a certain distance

• the speed of light and electromagnetic waves in km/sec.

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

• generate great amounts of light and heat.

• seem small light points.

• are millions of kilometres away from each other.

• no correct answer