Unit 4: The Solar System

The Solar System

Our solar system consists of the Sun, eight planets, more than 130 planetary satellites, like the Moon, comets and asteroids.





Stars are self-luminous objects. Stars shine because they release energy produced by nuclear reactions at their core.



Planets are large objects that move around a star. There are eight planets in the solar system. All the planets in our solar system orbit the sun.



Asteroids are large rocks. There are lots of asteroids in the Asteroid Belt between the orbit of Mars and Jupiter.


The Earth rotates on its axis. This movement is the Earth's rotation. One rotation takes twenty-four hours. We call this a mean solar day.


Day and Night


The rotation of the Earth causes day and night. When we are facing the Sun, our side of the Earth is illuminated and it is daytime. When we are facing away from the Sun, it is dark and it is night-time.



The Earth's Revolution


The Earth orbits around the sun. This is called revolution and it takes approximately 365 days to complete.  The Earth's orbit around the sun is elliptical.



The Seasons


The seasons are a result of the incline of the Earth's axis. This incline means different parts of the Earth recieve different amount of sunlight and heat.


When it is summer in the Southern Hemisphere it is Winter in the Northern Hemisphere because the Southern Hemisphere is facing the Sun.


As the Earth orbits the Sun, the Northern Hemisphere moves to face the Sun and it becomes Summer there.



The Moon




The Moon is the only natural satellite that orbits the Earth. A satellite is an object that revolves around another object.


New Moon


The dark side of the Moon faces the Earth. The Sun does not illuminate the Moon so we cannot see it.

Waxing Moon


The part of the Moon that is illuminated is growing.

Full Moon


The Moon's completely illuminated side is facing the Earth.

Waning Moon


The part of the Moon that is illuminated is getting smaller.


The Four Compass Points


The four compass points are north, east, south and west. We use these points to navigate and read maps.




Maps show representaions of the Earth.



Information on Maps






The Key shows what the different symbols mean.




The scale shows the relationship between the size of something on the map and its real size.





The North Arrow shows the direction of North.