CH 11 : Star And Galaxies

Question 1

What is galaxies

Answer 1

Combination of stars , planets , gaxes , dust in space

Question 2

List three types o galaxies

Answer 2

Spiral , elliptical , irregular

Question 3

What made up of these three galaxies

Answer 3

Spiral ( middle aged star )
Elliptical ( old star )
Irregular ( young star )

Question 4

Why elliptical galaxies contain mostly old star

Answer 4

Because lack of oxygen , dust and gas therefore no new stars formed

Question 5

Why sun is known as a star

Answer 5

1. Because contains mostly hydrogen and helium

2. Produce energu through nuclear fusion

Question 6

List the order from univrse —> ?

Answer 6

Universe - galaxies - the milky way - solar system - 8planets - earth

Question 7

States the characteristics of star

Answer 7

Colour , temperature , size , brightness , distance

Question 8

Give some explanation about te characteristics of star

Answer 8

1. C olour ( depends on surface temperature )
2. Temperature ( red = cold , blue = hot )
3. Brightness ( depends on size , distance , luminosity , temperature )
   Brighter star - bigger , closer to earth , brighter , hotter
4. Distance ( closer , brighter )
5. Size ( dwarf star > sun > giant star > supergiant star )

Question 9

Explanation about birth of star

{ GCH = GO CANADA HILLS }

Answer 9

1. Gases and dust in the nebula are pulled bby strong (g)ravitaional forces untill it becomes compact / dense
2. a (c)ore is formed which is hot and dense
3. The core becomes (h)otter when temperature and pressure increase. This cause nuclear reacions take place. Hyfrogen is changed to helium
4. A star is formed

Question 10

Explanation about death of star ( medium sized )

{ NGOC = Never Give On Call )

Answer 10

1. When hydrogen in the star is all used up, the (n)uclear reaction stops
2. The (g)ravitaionall pull become weaker , the star expands and forms red giant
3. The (o)uter layer of star breaks up and drifted to outer space
4. The (c) ore cools down then star shrinks into white dwarf

Question 11

Eplanation about death of star ( large , superlarge )

Answer 11

1. When hydrogen in the star are all used up , the nuclear reaction stops
2. The gravitationall pull become weaker , the stars expands and forms red giant.
   - red giant continue to expand to form red supergiant
3. Red supergiant explodes
   - explosion known as supernova
4. Neutron star is formed ( large star ) //// black hole is formed ( superlarge star )