Prepared by : PN WAHYU AKMAL BT HUSSEIN

Characteristic of the sunDiameter : 109 times larger than earthMass : 33 420 times the mass of earthDensity :1485kg/m3 (0.27 x earth)Surface temperature : 5100-6000oCComposition : Hydrogen gas (70-80%) &

Helium

Structure of the sunSun’s atmosphere divided into 3 layers :

Corona, Chromosphere Photosphere

Corona : Thin layer of gas, visible during total solar

eclipse Bluish white layer Temperature : 2,000,000oC

Chromosphere 9600km thick Temperature 15,000oC Reddish during solar eclipse

Photosphere Can be seen from earth 400km thick Temperature 6000oC

Core Temperature 15 000 000oC Hydrogen is changed to helium

Sunspots Dark patches Magnetically active spots Cause changes in earth climate; e.g extreme

droughtProminences

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 communicationsClimatic disturbances on earthAurora (the sky in the polar regions apperas

colourful)

Solar flaresHuge cloud of hydrogen that causes violent

explosionsCauses

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

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 earthColour & Temperature: blue coloured has

highest temperature, red coloured have the lowest temperature

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.

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.

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.