Nani

NAME : YUSRINANI IBRAHIM FORM : 2 TEGAS 2008 CHAPTER : STARS AND GALAXIES

THE SUN   

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Characteristics of the Sun Structure of the Sun Phenomena on the Surface of the Sun Generation of Energy by the Sun

Characteristics of the Sun    

A ball of glowing gases consisting of mainly hydrogen and helium. Diameter about 1,400,000 km or 100 times of the Earth’s diameter. Mass about 1.99×10³ºkg or 330,000 times of the Earth’s mass. Produce strong gravitational force which about 28 times greater than force produce by the Earth.

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Density about 1500 kg/m³ Low density because its gaseous state. Surface temperature about 6,000ºC. Temperature at the centre of the Sun reaches 15,000,000ºC.

Structure of the Sun 

Sun’s atmosphere divided into 3 layers :  Corona  Chromosphere  Photosphere

Structure of the Sun

CORONA       

Outermost layer of the Sun. Extends hundreds of km from the centre of the Sun. Faint & only visible during total eclipse. Has bluish-white & pearly appearance. Is a hot gas boiling off the Sun. Streaming outwards in all directions into space in the form of solar wind. Temperature can reach 2,000,000ºC.

CHROMOSPHERE  

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Middle layer of the Sun. Area above the photosphere that is pink or red. Not as bright as the photosphere. Can be seen during an eclipse of the Sun. Temperature about 15,000ºC. Temperature much higher as it approaches the corona.

PHOTOSPHERE  

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The innermost layer of the Sun. The surface of the Sun that is normally seen. 500 km thick & consists of dense gases. Have grainy surface caused by the convection of hot gases bubbling up to the surface. Temperature about 6,000ºC. Temperature rises higher as it gets nearer to the chomosphere.

Phenomena on the Surface of the Sun 

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The phenomena often change Earth’s weather, produce communication problems & create disturbances in transmission of radio & television. Observable phenomena that occur on the photosphere :   

Sunspots Prominences Solar flares

Phenomena on the Surface of the Sun

SUNSPOTS   

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Dark areas on the Sun’s surface. Appear dark because they are cooler than the surrounding areas. Represent large eruptions of the photosphere that may last for more than 1 week. Often exist in pairs or in groups. Come & go in an eleven-year cycle.

PROMINENCES 

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Throw out matter from the Sun into space at speeds ranging from 600 km/s to more than 1,000 km/s. Others form huge loops or arching columns of glowing gases over sunspots that can reach heights of hundreds of thousands of km. May last for a few days or for a few months.

SOLAR FLARES      

Violent & spectacular gas explosions. Often occur near sunspots. Made up of numerous charged gaseous particles. The charged gaseous particles often interact with Earth’s magnetic field producing aurora. Aurora in north pole = aurora borealis / northern lights. Aurora in south pole = aurora australis / southern lights.

Generation of Energy by the Sun 

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Temperature in the core of the Sun & intense heat causes nuclear reactions. In nuclear reaction, 4 hydrogen atoms fuse to form helium atom which called nuclear fusion. Nuclear reactions produce large amount of energy. The sun then gives it out in all directions as heat & light.

STARS & GALAXIES IN THE UNIVERSE 

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Formation and Death of Stars Galaxies The Milky Way

Stars 

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Defined as a ball of a very hot gases which produces its own heat and light. Classified into various types based on their brightness, colour, size and temperature. The brightness of a star as viewed from the Earth depends on:  the size of the star.  The distance between the star and the Earth.  The surface temperature of the star.

Super giants

I N C R E A S I N G

B R I G H T N E S S

20 000

15 000

10 000 Temperature (K)

giants

6 000

3 000

Blue giant Red dwarf Yellow giant.

White dwarf

Orange giant    

The temperature of a star determines the colour of its light. The stars with a higher temperature have a bluish-white light. The stars with lower temperature glow with a red light. The stars with medium temperature, like a sun, have a yellow light.

Formation and Death of Stars Nebula Star with mass up to 1.4 times that of the Sun Red giant White dwarf

Nebula Star with mass of between 1.4 to 3.0 times that of the Sun Red giant Supergiant Supernova Neutron Star

Nebula Star with mass of more than 3.0 times that of the Sun Red giant Supergiant Supernova Black hole

Galaxies   

A group of stars. Classifies based on their shapes. Common types :  Spiral (has arm spiralling outwards from central bulge)  Elliptical (oval shaped)  Irregular (no obvious shape)

Galaxies

Elliptical galaxy

Spiral galaxy

Irregular galaxy

The Milky Way  

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Example of a galaxy. Measure about 100,000 light year across. Contains more than 200 billion stars. The Earth & the rest of Solar System lie about 32,000 light years from the middle of the Milky Way.

The Milky Way

From the side

From the top

THANKFUL FOR THE EXISTENCE OF THE UNIVERSE AS A GIFT FROM GOD 

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Importance of the Sun & the Moon to Life on Earth The Expanse of the Universe

Importance of the Sun & the Moon to Life on Earth  

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Main source of energy for the Earth. Light energy from the Sun is used for making food in plants. Heat from the Sun warms the Earth. Without sunlight the water cycle will be broken. The moon’s gravity causes tidal changes.

The Expanse of the Universe   

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The universe is a collection of all matter, energy & space that exists. There are no actual facts about how the Universe began or how it will end. Based on Big Bang Theory, about 12 to 15 billion years ago, it began with an enormous explosion. All that exists in the Universe not permanent but changes with time.

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