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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