F3 Chapter 9 Sun and Galaxies

8/22/2019 F3 Chapter 9 Sun and Galaxies

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Density:

about1500kg/m3

Diameter:

about

1 400 00 km =

100 x the Earth

diameter

Mass:

1.99 x1030kg

Temperature:

Surface-6000C

Centre of the Sun-15 000 000C

Produces a strong

gravitational forces =

about 28 times greater

than the gravitational

force produces by the

Earth


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Middle layer

Can only be seen

during an eclipse

The temperature

about 15 000C

Outermost layer

Extends hundreds of

kilometers from the centre of

the Sun

The temperature can reach

2 000 000C

Surface of the Sun

About 500km thick

Consists of dense gases

The temperature is about6000C


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ProminencesThrow out matter from the Sun into space at

speeds from 600km/s to more than 1000km/s

Last for a few days or even for a few month

SunspotsDark areas on the Suns

Cooler than the surrounding areas

May last for more than a week


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Solar Flares

violent and spectaculars gas explosion

that often occurs near sunspots made up of numerous charged gaseous

particles from the Sun shooting outward at high

speed into outer space

interact with Earths magnetic field producing

dazzling light display called aurora

Aurora

Borealis,

(northern light)

Aurora

Australis,

(southern

light)


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Composition of Sun ishelium and hydrogen

Because of the

temperature, thermonuclear

reactions occur in the Suns

core

@ Release large amount

of heat and light energy

Temperature reach15 000 000 C

Energy from the core is

distributed by the

processes ofradiation and

convection

Sun energy is emitted as

electromagnetic waves


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Star with

mass

3 x

Sunsmass

Star with mass 1.4

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,

its 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 Suns

mass, 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 Suns

mass, 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 vast collectionscalled galaxies

Our Solar System with only one star, the Sun, formsa tiny part of galaxy called the Milky Way

Galaxy are classified into various type based on the

shaped.

Three common types of galaxies are spiral,

elliptical and irregularshaped


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Large galaxy with 20 000

to 100 000 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 is

3 000 to 10 000 light years

Smooth and rounded or

oval in shape

Brightest at the centre

and fades towards theedge

Consists of mainly old

Star

60% of galaxies are

elliptical

Diameter of this galaxy is

25 000 to 32 000 light

years

No definite shape and

exists in various forms

Consists of bluish-whitestars (young star) and

nebulae

10% of galaxies are

irregular


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Aspiral-shaped galaxy with a diameter of 100 000 light yearsand is about 10 000 light years thick

Consists of old stars at the centre at the center and nebulae

(dust and gases) at spiral arms

Stars in Milky Way galaxy are so close together and

observed as hazy patches

The Sun is 30 000 light years from the center of Milky Way

The Sun takes 200 million years to orbit the centre of the

Milky Way


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Main Source

of Energy

Sunlight is essential for

photosynthesis

Causes water to

evaporate

produces 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 exactly how the

Universe began or how it will end.

Among the various scientific

theories about the formation of

the Universe, the most widely

accepted scientific theory is the

Big Bang theory

According to the Big Bang

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


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F3 Chapter 9 Sun and Galaxies