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Contents.

Star And Galaxies

The SunThe Stars and the Galaxies in the universeExistence of the Universe as a Gift from God


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i) The Sun..t h e c e n t r e o f o u r s o l a r s y s t e m

T h e S u n i s a c t u a l l y a

s t a r o f m o d e r a t e s i z e

T h e S u n t a k e s 2 5 a n d h a l f d a y s t o r o t a t e

o n i t s a x i s from west to east

Photograph 9.1: The Sun

Characteristics of The Sun Measurement


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Characteristic ofCorona

- o u t e r m o s t l a y e r o f g a s i n t h e

S u n s a t m o s p h e r e corona forms a circle of white light around the

Sun - o n l y v i s i b l e d u r i n g e c l i p s e o f

t h e S u n

- t e m p e r a t u r e i s a b o u t 1 . 5 m i l l i o nd e g r e e C e l s i u s

Chromosphere - b r i g h t r e d l a y e r o f g a s b e l o w

t h e c o r o n a - o n l y v i s i b l e d u r i n g e c l i p s e

o f t h e S u n ju s t l i ke t h e corona

- t e m p e r a t u r e v a r i e sb e t w e e n 1 0 0 0 0 a n d

5 0 0 0 0 0 d e g r e e Celsius

Photosphere. - c o m p a c t l a y e r o f g a s s e e n t o

b e s h i n i n g w i t h y e l l o w light from EarthoPhotospheres surface appears turbulent because

gas fromthe Suns core is release to its surface - T h i s l a y e r i s r e s p o n s i b l e f o r

r a d i a t i n g h e a t a n d l i g h t from the Sun


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Suns Core - c o n s i s t o f h y d r o g e n a n d h e l i u m

g a s e s - n u c l e a r r e a c t i o n o c c u r s i n t h e c o r e

a l l t h e t i m e t o generate and release heat and

light energy -

Thecorestemperature is extremely high. Itsabout 15million

degree Celsius

Photograph 9.2: corona and chromosphere can only be

seenduring an eclipse of the Sun


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Phenomena of that occurs at the suns

atmosphere

Few of phenomena that occur at the Suns atmosphere

are:

Prominences Solar flares Sunspots

Figure 9.2: Figure above shown prominence, solar

flareand sunspot


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phenomena Descriptions

Prominences - a n e x p l o s i o n o f h o t g a s t h a t s h o o t so u t f r o m t he S u n s chromosphere with shiny

brightlight

- c a n b e e n s e e n n e a r t h e e d g eo f t h e S u n during an eclipse of the Sun

p r o m i n e n c e e m i t s c h a r g e d

p a r t i c l e s a n d ultraviolet rays into outer space

Solar flares - a s t r o n g e x p l o s i o n o f g a s e s t h a t h a p p e n suddenly into outer

space

- a l s o e m i t r a y s l i k e g a m m ar a y s a n d X - r a y s

h i s p h e n o m e n a o c c u r s f or o n l y a f e w minutes or a few hours butit release a greatdeal of energy

sunspots - d a r k s p o t s o n t h e s u r f a c eo f t h e S u n s Photosphere

-h a s a l o w e r t e m p e r a t u r e (

4 0 0 0 d e g r e e Celsius ) than its surroundings

( 6000 degreeCelsius )


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The effect of the phenomena on the surfaceof

the Sun on Earth

- c h a r g e d p a r t i c l e s a s a r e s u l t o f s o l a r f l a r e sr e a c h t h e N o r t h P o l e o r t h e South Pole of the Earth

and collide with gas molecules in the atmosphere

- a s a r e s u l t , c o l o r f u l l i g h t t h a t c o n s i s t o f g r e e n , y e l l o w a n d r e d l i g h ts a r e produced. These

light that can be seen at night are called aurora - t h e c h a r g e d p a r t i c l e s a n d r a d i a t i o n f r o m t h e

S u n l i k e c o s m i c r a y s , X - r a y s and gamma rays will

collide with particles in the Earths atmosphere

- t h i s c a u s e s d i s t u r b a n c e t o t h ec o m m u n i c a t i o n s s y s t e m l i k e t e l e v i s i o n a n d radio

broadcast, telegraph transmissions and telephone calls.


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Generation of energy by the Sun

c o n s i s t o f h y d r o g e n a n d h e l i u m g a s e s

n u c l e a r r e a c t i o n t h a t t a k e s p l a c e

i n t h e S u n s c o r e g e n e r a t e s e n e r g y.

D u r i n g a n u c l e a r r e a c t i o n , 2 h y d r o

g e n a t o m s f u s e t o f o r m o n e h e l i u m

at om .H ea t an d l i gh t e ne rg y a r e released.

Figure 9.3: Nuclear reaction that occur in the Suns core


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What is Star ?

Star-a na tura l ob jec t in ou te r sp ace tha t can

re le as e hea t an d light energy-g en er at es en er gy

through nuc lea r reac t ions Sun

- a s t a r t h a t i s n e a r e s t t o E a r t h Distance of

a star from the Earth is measured in units of

light year,-distance traveled by light in a year. There

are bright stars in the sky can been seen by naked eye atnightsuch as the Sirius and Rigel.


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Classification of stars-S ta r s need to be c lass i f ied to fac i l i t a te

research and classified according to

characteristics such as

t e m p e r a t u r e s i z e b r i g h t n e s s

-A star with very lo temperature is red in colour. A star

that very hotis blue in colour.Dwarf star -very small star, smaller than EarthGiant star -tens of times bigger than the SunSupergiant star -very big star, 100 times bigger than theSun


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Apparent magnitude

measurement of the brightness of object in theskythat can be seen from Earth. The lower the magnitude

value, the brighter the object.

Figure 9.4: Apparent magnitude reading.


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Birth and death of star

Star - born from nebula

Nebula - a la rg e clo ud th at co ns is t of du st

and gases - gases and particlesin the nebula are pu

lled by stronggr avi ta tio na l fo rce to

form a lump and causes the lump of gases to sh i rk and i s compressed

unt i l i t becomes very compact to form a

core- - when tempera ture and pressure in

the core become veryhigh, nuclear

reaction occurs and hydrogen gas is

turnedinto helium. A lot of heat and lightenergy are releasedthe, the core shines and a

star is born.

The star will die when all hydrogen gas inits core is use dup in nuclear reaction.


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The star will undergo death in by following stages

withA star of moderate size like Sun:

1.the hydrogen atoms in the star are used up and

nuclear reaction stops

2 . thes ta rexpandsbecause i t s g rav i ta t iona l force hasdecreased and forms a red giant

3.the outer parts of the star drift out into space

leavingthe extremely hot white core called the white

dwarf

4.the with dwarf is a star that is dense, compactand becoming increasingly cold5.the, its continues to become colder and eventually

leavesa black body or black dwarf (looks dark in outer

space)


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A star that is bigger than the Sun:

1 . t h e o u t e r l a y e r o f t h e s t a r e x p a n d s a s

a r e s u l t o f decreasing gravitational force to form a

red giant2.i t c o n t i n u e s t o e x p a n d a n d f i n a l l y e x p

l o d e s a s supernova. A great deal of heat and

light energy are produced

3 .very s t rong grav i ta t iona l fo rce in the core

of the star converts it into either a neutron star or

black hole.


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Black hole- an object that is very dense and has

stronggravi ta t ional force tha t pul ls a l l s ur rounding mate r ia l s , including light, that is close by, to

it. Black hole also cant be seen in outer space.

Neutron star- a very small and dense star as it

consistmainly of neutron particles.


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ConstellationConstellation

-a group of stars that forms a certain patternin the sky

and i n a n c i e n t t i m e s , k n o w l e d g e o f

t h e c o n s t e l l a t i o n w e r e used as a calendar

and compass.

Figure 9.5: Example of constellations


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Types of galaxy

Classified according to:

- e l l i p t i c a l g a l a x i e s

- s p i r a l g a l a x i e s

- i r r e g u l a r g a l a x i e s Shape of galaxies Example of galaxies

elliptical Galaxy M87 in virgo

spiral Milky way and andromeda

irregular Magellan cloud

Table9.3: Shows the shape and example of galaxy


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The Milky Way...

-our so lar i s in a ga laxy ca l led the Mi lky

Way.

- T h e S u n i s o n e o f t h e m i l l i o n s o f

s t a r s i n t h e M i l k y W a y .


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The expanse of theuniverse ...

Many scientist believe in the theory that the

Universe beginswith a huge explosion, the Big

Bang. During the explosion,the Universe

expanded from nothing to become a hugespacemeasuring 2 billion billion kilometers

in width, in a singlesecond.


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The universe as a giftfrom god

At present, scientists still cant explain

why the BigBang occur. We should

appreciate the uniqueness,

orderliness, beauty and harmony in the

Universe as a sing Of the gloryof God.

star n galaxies

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