What is in our Solar System?
1 Sun
8 Planets ( 170 Moons)
5 Dwarf Planets
1 Asteroid Belt
Various
Comets
Meteoroids
Asteroids
Left over debris (Kuiper
Belt)
Planets

A planet is an object which orbits a star.

Planets divide into 2 main groups: terrestrial planets
and giant planets. Terrestrial planets have a solid surface, like
the Earth. Giant planets are made of layers of gas, or ice, with
small rocky cores.

The terrestrial planets in our Solar System are:

Mercury

Venus

Earth

Mars

The giant planets in our Solar System are:

Jupiter

Saturn

Uranus

Neptune

The 4 planets closest
to the Sun are the
inner or terrestrial
planets. They are
small, warm, rocky
worlds, with few (or
no) moons and no
rings. They
are: Mercury, Venus, E
arth, and Mars. Venus,
Earth, and Mars all
have atmospheres an
d weather.
The 4 outer planets are larger and
cooler. They contain gases (plus
ices). Together they contain 99% of
the mass that orbits the Sun. They
are often called giant planets. There
are gas giants: Jupiter and Saturn.
And ice
giants: Uranus and Neptune.
What is the structure of our planet?

Earth is the third planet from the Sun. It is the largest of four rocky, or
terrestrial, planets. It is the only place in the Universe where we
know life exists
Investigating Four Spheres of
Earth

Everything in Earth’s system is placed into one of the four subsystems:
land, water, living things, or air. The subsystems are known as “spheres.”
Specifically, they are known as the geosphere (land), hydrosphere
(water), biosphere (living thing) and atmosphere (air).
The gaseous component above the surface of the Earth is known as the
atmosphere. It is made of gaseous components and tiny water particles. The
gases in the atmosphere are kept in place by the force of gravity. The heat from
the sun is radiated to the Earth and is reflected in the atmosphere. The heat
from the sun warms up the surface of the earth and causes evaporation,
thereby sending moisture into the atmosphere.
The atmosphere comes in layers and the illustration below shows the different
layers of the atmosphere. The troposphere is the layer closest to Earth.
Humans, animals and plants live in this layer. Birds and aeroplanes also fly in
this layer of the atmosphere. In the layers above the troposphere, the air
becomes thinner. Beyond the exosphere is space.
No sphere works on its own. All the
spheres in the system interact and overlap.
In the section, we shall discuss the various
interactions that occur among the spheres:
1. Hydrosphere and Atmosphere
The evaporation that occurs in the
hydrosphere forms the medium for cloud
and rain formation in the atmosphere. The
atmosphere brings back this water to the
hydrosphere in the form of rain.