1. CHAPTER 9 :
STARS AND
GALAXIES
Prepared by :
Pn. Noor Hazwani bt.Alias
SMK Sg.Maong,Kuching

2. The Sun

3. The Sun
- Shape like a ball.
- Made up of hot gases : hydrogen and helium
- Surface temperature : 5 500 - 6 000 oC
- The Sun is one of the many billions of stars.
- Nearest star to Earth. That is why it appears bigger and brighter
than other stars.

4.  Has three layers
Structure of the Sun
Corona Chromosphere
Photosphere
can only be seen clearly
during solar eclipse.
can be seen clearly
everyday

5. Solar eclipse
Corona and Chromosphere
can only be seen during solar eclipse.
Corona Chromosphere

6. Phenomena on The Surface of The Sun
Prominence
-arches or loops shape.
-eruption of chromosphere
(2nd layer)
Solar flare
- explosion near sunspots
- release charged
particles into outer space.
(Examples:
* Electrons,
* X-rays,
* Ultraviolet rays)
Sunspot
- cool spot
- eruption of
photosphere
(1st layer)

7. Aurora
 Dazzling,colourful light.
 Occur at north pole and south pole of Earth.
 Charged particles interact with Earth’s magnetic
field.
Solar flare
-release charged particles
(Examples:
* Electrons, * X-rays, * Ultraviolet rays)

8. How the Sun produces energy?
Nuclear reaction (in the core)
 4 hydrogen atoms  1 helium atom + light energy + heat energy
+
Light and
heat energy

9. Various types of Star
 Size

10.  Temperature and colour
Various types of Star
Blue
Hottest star
Yellow
Medium
temperature
Red
Coolest
star
Colour Temperature Example:
Blue 40 000 0C Spica
Bluish-
white
10 000 0C Rigel
Yellow 6 000 0C The Sun
Red 3 000 0C Betelgeuse
Medium
temperature

11.  Brightness.
Various types of Star
Rigel
Sirius
Sirius
Rigel
Procyon
Achernar
5 brightest star

12. Formation of Stars
Gases
(hydrogen)
Dusts
A
nebula
A core is
formed.
-very hot and
dense
-The core
becomes hotter.
- Nuclear
reactions take
place.
A STAR IS
FORMED !!
1.
*Nuclear reaction (in the core)
 4 hydrogen atoms  1 helium atom + light energy + heat energy
3.
2.
Gases and
dusts in a
nebula are
pulled by
strong
gravity
forces until
it become
compact
(dense).

13. Death of Star
*depends on the size of the star
Nebula

14. Death of Star
*medium size star, such as The Sun
2. *gravity pull weakens.
*the star expands
and forms red giant.
1. *Hydrogen atoms
in the star are all
used up.
* Nuclear reaction stops.
3. *Substance at the outer
part of the star
escape to outer space.
4. *A white core or
a white dwarf is
formed.
Medium size star
Black Dwarf

15. Death of Star
*large star and super large star
star
* DEATH OF LARGE
STAR
(10 x Sun’s mass)
* DEATH OF
SUPER
LARGE STAR
(100 x Sun’s
mass)
1. *Hydrogen atoms
in the star are all
used up.
* Nuclear reaction stops.
2. * Gravity pull weakens.
* The star expands
and forms red giant.
* The red giant continue to
expand to form red
supergiant.
3. *Red supergiant
explodes.
*The explosion is
known as supernova.
Nebula
Neutron star :
*consists of neutrons.
*rotates and gives out radio
waves.
Black Hole:
*cannot be seen.
*dense.
*has very strong gravity force.

16. Constellation
 A group of stars arranged in specific pattern.
 In the past, constellation were used as :
a) compass (to show direction).
b) calender
A
constellation

17. Constellation
North
Big dipper
Examples :
South
North
Southern
cross

18. Universe and Galaxies
Universe
Galaxies
Solar System
Earth
Human being
Milky Way
(our galaxy)
*Notes
The Universe :
-a very huge space
-holds everything from
the smallest particle to
the largest galaxy.
-there are billions of
galaxies in the Universe.
Galaxy :
-Each galaxy has billions
of stars.

19. Hubble Space Telescope
-is used to observe galaxies

20. Galaxies
Spiral galaxy Irregular galaxy
(no obvious shape)
Elliptical galaxy
(oval shape)
- A galaxy contains billions of stars.
- Has many shapes.

21. Our Galaxy : The Milky Way
Spiral shape