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1. Identify the chemicals
that make up stars.
2. Understand how
different natural forces
affect how stars look.
3. Explore how stars have
constantly changed outer
space over time.
A star is a hot
glowing sphere of gas
that produces energy
by fusion held
together by gravity.
Fusion means ‘joining
together’.
Astronomers say…
Without stars,
there would be no
planets and no life.
Humans consist of
the elements that
the stars have
made.
Have you ever been
caught in the middle
of a large crowd?
How did it feel?
If you remember feeling
hot or pressured, this is
similar to what happens
to hydrogen atoms in
the core of a star, where
the temperature and
pressure are very high.
Gravity forces the hydrogen atoms together so
strongly that they fuse. When that happens, a new
element called helium is formed and a little bit of
energy is released. We call that energy starlight.
How bright the star
looks to us on Earth
depends on 3 things:
1. Star size
2. Distance from Earth
3. Star temperature
A star’s temperature can be determined by
its colour.
Colours hottest to coolest:
Blue/white  yellow  orange  red.
NEBULA: A large cloud of
gas (helium and
hydrogen) and dust
which forms into a star.
Dust and gas particles
exert a gravitational
force on each other
which keeps pulling
them closer together.
As the particles pull
closer together the
temperature increases.
At 10,000,000o C fusion
takes place and energy
radiates outward
through the condensing
ball of gas.
Fusion uses up a star’s
hydrogen supply rapidly
causing the core to heat
up and the outer
temperature to fall.
The star expands and
becomes a red giant.
As the core uses up
its helium supply,
the outer layers
escape into space
and the remaining
core is white hot
and called a white
dwarf.
When no more material is
left in the core it explodes
into a supernova.
Smaller stars become
neutron stars and most of
the massive ones will
collapse into
a black hole.
Neutron star
Nothing (not even light)
can escape the gravity of a
black hole.
Heavy inner core.
Radiation zone:
Energy bounces back
and forth before
escaping.
Convections zone:
Cooler layer of gas
that is constantly
rising and sinking.
Photosphere: Bright
source of much of
the light we see.
Chromosphere:
Active layer which is
home to many
significant displays.
Cool dark areas on
the sun’s surface,
first discovered by
Galileo.
They appear and
disappear.
15 February 1564 – 8 January 1642
Galileo was an Italian
physicist, mathematician,
astronomer, and philosopher
who played a major role in the
Scientific Revolution.
His achievements include
improvements to the
telescope and observations of
the stars and planets.
A replica of the earliest surviving
telescope attributed to Galileo Galilei.
Violent eruptions
near a sunspot which
suddenly brighten
and shoot outward at
high speed.