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Density:about

1500 kg/m3

Diameter:about

1 400 00 km =100 x the

Earth

diameter

Mass:1.99 x

1030 kg

Temperature:Surface-6000CCentre of the

Sun-

15 000 000C

Produces a stronggravitational forces:about 28 timesgreater than the

gravitational forceproduces by the

Earth

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Middle layer Can only be

seen duringan eclipse

Thetemperatureabout

15 000C

Outermostlayer

Extendshundreds ofkm from thecentre of theSun

Thetemperaturecan reach

2 000 000C

Surface ofthe Sun

About500km thick

Consists ofdense gases

Thetemperatureis about6000C

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ProminencesThrow out matter from the Sun into space at

speeds from 600km/s to more than 1000km/sLast for a few days or even for a few month

SunspotsDark areas on the SunsCooler than the surrounding areasMay last for more than a week

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Solar Flaresviolent and spectaculars gas explosionthat often occurs near sunspotsmade up of numerous charged gaseousparticles from the Sun shooting outward at high

speed into outer spaceinteract with Earths magnetic field producingdazzling light display called aurora

AuroraBorealis,

(northernlight)

AuroraAustralis,(southern

light)

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qComposition of Sun ishelium and hydrogen

qBecause of thetemperature,thermonuclear reactions

occur in the Suns core

qRelease large amount ofheat and light energy

qTemperature reach 15000 000 C

qEnergy from the coreis distributed by theprocesses of radiation

and convection

qSun energy is emittedas electromagneticwaves

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Star

with

mass

3 x

Sunsmass

Star with mass1.4 to 3.0 x

Suns mass

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The diagram above shows the formation and death of stars Stars begin as a large cloud of gas and dust called nebula After ten thousands of year collapse, a hot core will be formed When the supply of gas in a star runs out, the star dies When a star with a mass of up to 1.4 times the Suns mass,

it will become a red giant The red giants then contracts, releasing its gas and turns into

white dwarf

When a star with mass of between 1.4 and 3.0 times the Sunsmass, it will become red giant then continues swell even

more to become supergiant

The supergiant then explodes producing supernova As the supernova collapse, a neutron star is formed

When a star with mass of more than 3.0 times the Sunsmass, it swell up become red giant then become supergiant

The supergiant then explodes producing supernova As the supernova collapse, its core becomes so massive that

its gravity sucks everything including light into it

The core is called a black hole

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Stars are grouped together in vastcollections called galaxies

Our Solar System with only one star, theSun, forms a tiny part of galaxy called

the Milky Way

Galaxy are classified into various typebased on the shaped.

Three common types of galaxies arespiral, elliptical and irregular shaped

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Large galaxy with 20kto 100k light years of

diameter Disc-shaped with @ centre : older stars @ spiral arms :

new stars, Gases and dust 30% of galaxies are

spiral

Diameter of galaxy is3k to 10k light years

Smooth & rounded /oval in shape

Brightest at the centre& fades towards the

edge

Consists of mainly oldstar

60% of galaxies areelliptical

Diameter of thisgalaxy is 25k to 32k

light years

No definite shape &exists in various

forms

Consists of bluish-white stars (youngstar) & nebulae

10% of galaxies areirregular

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A spiral-shaped galaxy with a diameter of 100k lightyears & is about 10k light years thick

Consists of old stars at the centre at the center &nebulae (dust and gases) at spiral arms

Stars in Milky Way galaxy are so close together &observed as hazy patches

The Sun is 30k light years from the center of MilkyWay

The Sun takes 200 million years to orbit the centre ofthe Milky Way

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Main Source

of Energy

Sunlight is essential for

photosynthesis

Causes water to

evaporateproduces rain

Calendars based on

phases of the Moon

Affect the occurance of

ocean tidal

Encourage the development

of technologies based

on the Moon travelling

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Nobody knows exactlyhow the Universe began or

how it will end.

Among the variousscientific theories aboutthe formation of the

Universe, the most widely

accepted scientific theory

is the Big Bang theory

According to the BigBang theory, about 12

billion to 15 billion

years ago, our

Universe began with

enormous explosion.

Since then, the

Universe has forever

been expanding

everywhere at the

same time