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Abdul Halim Abdul AzizUnit Penyelidikan Ilmu Falak dan Sains Atmosfera

Universiti Sains Malaysia

Apakah yang

menarik di angkasa

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December 29, 2009 2

Science? What Science?

The word science comes from the Latin word scientiaforknowledge, which in turn comes from scio- I know.

Scienceor scientiameant any systematic or exact recordedknowledge.

In a more restricted sense, science refers to a system of acquiring

knowledge based on the scientific method The scientific method has four steps

Observation and description of a phenomenon or group of phenomena.

Formulation of an hypothesis to explain the phenomena. In physics, thehypothesis often takes the form of a causal mechanism or amathematical relation.

Use of the hypothesis to predict the existence of other phenomena, or topredict quantitatively the results of new observations.

Performance of experimental tests of the predictions by severalindependent experimenters and properly performed experiments.

Scientists never claim absolute knowledge. Unlike a mathematicalproof, a proven scientific theory is alwaysopen to falsification, if newevidence is presented.
http://en.wikipedia.org/wiki/Latinhttp://en.wikipedia.org/wiki/Knowledgehttp://en.wikipedia.org/wiki/Scientific_methodhttp://en.wikipedia.org/wiki/Falsifiabilityhttp://en.wikipedia.org/wiki/Falsifiabilityhttp://en.wikipedia.org/wiki/Scientific_methodhttp://en.wikipedia.org/wiki/Knowledgehttp://en.wikipedia.org/wiki/Latin

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December 29, 2009 3

Astronomy : Scale and Distance

Can be measured in ly (light-year)

Other units are also used are parsec, dopplershift (z)

I ly is distance travelled by light in vacuumin one year

Speed of light is approximately 300,000 kmper second

1 ly is ~10,000,000,000,000 km or close to 10trillion km taking 1 s for each count, ittakes 300,000 years to count 10 trillion

1 pc is 3.261630751 ly

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99.85% of the Solar System mass is in the Sun

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Bintang-bintang

~6000 can be seen with

the naked eye

3000 in one night

There are much morestars than our naked eyes

can detect

Stars are not static, they

also move systematically

Slightly more than 50%

have companions

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Constellation Orion

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Structure of the Universe

The solar system is

located in a large group

of stars called the Milky

Way (Bima Sakti)

The Milky Way consists

~100 billion star

In a spiral, disk-like

formation

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The Milky Way has a

diameter of ~100,000 ly

The Solar System is on

one of the spiral arms

~33,000 ly from its

centre

Orbiting at 250 km per

second

Another famous galaxy is

Andromeda atau M31M100

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Andromeda is thelargest galaxy nearbythe Milky Way

~2.2 milion ly fromEarth

From end-to-end~125,000 ly

Furthest galaxy ~14billion ly

Besides spiral-shaped,galaxies are also seenas ellipse or irregular

Andromeda

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Far Galaxies

Galactic cluster

CL1358+62, 64 x 64, 5

billion ly

Gravitational lensing

brought a far galaxy

forward -> the red

crescent

Using doppler shift, ~13

bilion ly away

7% the age of the

universe

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How many galaxies

Estimated ~100 billiongalaxies in the

universe There are 2 million

galaxies (

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The Sun

Towards its end will become a red giant

Its size reach the orbit of Mars

After that it will cease burning and turn into a whitedwarf

End of thermonuclear process cease to be a star

Estimated life-span of the Sun is10 billion years

4.5 billion years have past

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Usia dan Kesudahan AlamSemesta

Alam semesta disangka bermula dari satu Big

Bang

Usia alam semesta dianggarkan sudah ~15 biliontahun.

Alam semesta sedang mengembang

Adakah ia akan terus mengembang?

Atau ia akan mengecut sebagai satu Big Crunch?

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