A presentation on stars and galaxies by my mother...

1. Prepared by : PN WAHYU AKMAL BT HUSSEIN

2.  Characteristic of the sun
 Diameter : 109 times larger than earth
 Mass : 33 420 times the mass of earth
 Density :1485kg/m3 (0.27 x earth)
 Surface temperature : 5100-6000o
C
 Composition : Hydrogen gas (70-80%) & Helium
 Structure of the sun
 Sun’s atmosphere divided into 3 layers :
 Corona,
 Chromosphere
 Photosphere

3.  Corona :
 Thin layer of gas, visible during total solar eclipse
 Bluish white layer
 Temperature : 2,000,000o
C
 Chromosphere
 9600km thick
 Temperature 15,000o
C
 Reddish during solar eclipse
 Photosphere
 Can be seen from earth
 400km thick
 Temperature 6000o
C
 Core
 Temperature 15 000 000o
C
 Hydrogen is changed to helium

5.  Sunspots
 Dark patches
 Magnetically active spots
 Cause changes in earth climate; e.g extreme drought
 Prominences
 Many thousand kilometres from the surface
 Gases (hydrogen & helium which consists of energetic
& electrically charged particles) escape to the outer
space, causes solar wind that will affect :
satellite, radio, television, telegraph and telephone
communications
Climatic disturbances on earth
Aurora (the sky in the polar regions apperas
colourful)

9.  Solar flares
 Huge cloud of hydrogen that causes violent
explosions
 Causes
 disturbances to telecommunication signals
 Changes in earth climate
 Magnet to malfunction in large solar flares
 Energy is generated from the sun when the
hydrogen gas is changed into helium gas.
 Energy is carried to the sun’s surface where
it is released as heat and light

10.  Star : made up of dust and gases (hydrogen
and helium)
 Sun is a star because it is made up of
hydrogen and helium
 Stars can be compared by :
 Size (neutron star -> supergiant star)
 Brightness : depends on surface temperature,
size & distance from earth
 Colour & Temperature: blue coloured has highest
temperature, red coloured have the lowest
temperature

11.  Nebulae is made up of dust and gases
(hydrogen & helium)
 Gravitational attraction will pull them
together and become stronger till a star is
formed
 The attractive force causes the star to
expand & the temperature rise
 The star will become stable if there is a
balance between the force pulling the star
together and the heat pushing the star apart.

13.  When the nuclear fusion of hydrogen and helium
has been completed, the core of the star will
getting smaller and smaller
 A lot of heat is generated and heat up the
outermost layer of the star.
 Hydrogen starts to burn, star will expand and
appears red in colour
 If red giant is not massive, white dwarf is formed
 If red giant is big, a supernova will occur n
neutron star formed
 If the original star is superlarge star, a black hole
will be formed.

15.  Galaxies is a gathering of billions of stars and
planets, dusts and gases.
 3 types of galaxies:
 Spiral
 Elliptical
 Irregular
 Our solar system is in the Milky Way, a spiral
shaped galaxy
 The solar system occupies only a small part of
the Milky Way
 The universe consists of all the matter, energy
and space that exist. It contain billion of
galaxies, stars, planets and particles.