Name : Nur Izzati Sofea Binti Ahmad Sofi

Form : 203 Courageous

Collage no. : 11092

Characteristic of the sun

At the center of Solar System One of the billion stars seen at night in our galaxy A huge mass of hot, glowing gases Nearly 110 times bigger than the Earth It is about 150 million km away from Earth Medium-sized star known as a yellow dwarf The largest object in the Solar System

Property characteristic Characteristic compared to Earth

Diameter 1 392 000 km 109 times the diameter of Earth

Mass 1.989 × 1034 kg 333 420 times the mass of Earth

Density 1 485 kg m-3 0.27 times the density of Earth

Surface temperature 5 500-6 000 oC 227-273 times the temperature on Earth

Composition Composed of about 70% hydrogen, 28% helium, and other elements such as carbon, nitrogen, oxygen, silicon and iron which amount to less than 2%

The Earth’s atmosphere contains oxygen, nitrogen, carbon dioxide, inert gases and water vapour

Structure of the Sun

The Sun’s atmosphere consist three part. The part are:

Corona

Chromospheres Photosphere

Characteristic of:

Corona

Outermost layer of gas in the Sun’s atmosphere Forms rings of whitish-blue light Only visible during total solar eclipses It temperature is about 1 000 000 oC

Chromospheres

layer above the visible photosphere this layer is about 10 000 km thick glows red because hydrogen gives off a reddish colour at this high

temperature only visible during the total eclipse

Photosphere

Innermost atmosphere layer of dense gases Photosphere’s surface appears turbulence because gas from the Sun’s

core is release to its surface This layer is responsible for radiating heat and light from the Sun

Sun’s core

Consist of hydrogen and helium gases Nuclear reaction occurs in the core all the time to generate to release

heat and light energy The core temperature is extremely high. It is about 15 million degree

Celsius

Structure of the Sun showing some phenomena on its surface

Phenomena on the Sun’s surface

Prominences, solar flares and sunspots are examples of phenomena that occur on the surface of the Sun

These phenomena are believed to occur because of the changes in magnetic field of the Sun

Prominences

Immense clouds of glowing gases that erupt from the upper chromosphere

The loop or arches of gases may shoot as high as 100 000 km from the Sun

Can from two to three months Visible during solar eclipses

Solar flares

the result of violent energy explosions in complex sunspot group release gases and charged particles far into space its temperature can reach up to 5 million degree Celsius emit electrons, visible light, and radiation it make the night sky above the Earth’s poles appear colourful. This

known as an aurora

Sunspots

dark regions which are visible on the photosphere appear dark because they are much cooler than their brighter

surroundings. Usually appear in groups and are of different sizes

Effect of the sun phenomena on Earth

The phenomena that occur on the surface of the Sun have various effects on Earth

The eruptions of prominences and solar flares release large amounts of solar material into space

Gases that escape to space carry a stream of electrically charged particles of energy

The continuous flow of these particle from the surface of the Sun causes a phenomenon known as solar wind

Communication system

the Earth’s atmosphere plays an important role in reflecting radio sigals in communication

solar wind affects radio communication as it causes radio signals to fluctuate

navigation system and compasses

radio signal from transmitter are used by ship and aeroplanes to determine their location

solar wind disrupts the radio signals of the transmitter, resulting in inaccuracies in the navigation systems

intense solar flares send out continuous streams of electrically charged particles which interfere with the Earth ‘s magnetic field and compasses

satellites and astronauts

the ultraviolent rays and X-rays given off by solar flares heat up the Earth upper atmosphere

high energy particles released by intense solar flare increase radiaton hazard and pose a threat to the health of astronauts in space

power generation

the charged particles interfere with Earth’s magnetic field and induce surges in the electric current along power transmission lines

this overloads the power grids and causes blackouts over large areas

global climate

sunspots bring about changes in temperature, humidity and atmospheric pressure, which affect the weather conditions on Earth

wind, land and sea breezes are affected by sunspot

formation of aurorae

aurorae are bands of coloured lights visible in the night sky, especially at the polar regions of the Earth

fluctuations in the solar wind can cause them to be visible at lower altitudes

generation of the energy by the Sun

consist of hydrogen and helium gases nuclear reaction that take place in the Sun’s core generates energy during a nuclear reaction, 2 hyrogen atoms fuse to form one helium

atom. Heat and light energy are released

Definition of a star

celestial body that released its own heat and light made of dust and gases like hydrogen and helium They generate energy through nuclear reactions

The sun as a star

The sun is a medium-sized star A star that is nearest to Earth Formed in a huge cloud of gas and dust called a nebula It is a huge sphere made up mainly of hydrogen and helium Generate heat and light, and releases energy through nuclear fusion The sun is about 4.6 billion years old

Various type of stars

From Earth, all the stars in the sky look alike.

However, each star has its own characteristic Astronomers use some of these characteristics to classify the stars

- colour- temperature- brightness- size

The colour and temperature of stars

Colour of a star indicates its temperature The hottest stars are blue The coldest stars are red The Sun, which is yellow in colour, is a star of average temperature

Class

Colour Surface temperature (oC)

Example

O Blue More than 25 000 SpicaB Whitish-blue 11 000 – 25 000 RigelA White 7 500 – 11 000 SiriusF Yellowish-white 6 000 – 7 500 Procyon AG Yellow 5 000 - 6 000 The SunK Orange 3 500 – 5 000 ArcturusM Red Less than 3 500 Betelgeuse

Size

Neutron star > white dwarf > the Sun > giant star > supergiant star

Type of star White dwarf

dwarf Giant supergiant

Relative size (the sun = 1)

0.1 10 10 - 100 >100

Brightness

Brightness of a star known as the apparent magnitude. It is determine by naked eye

A star with apparent magnitude of 1 is the brightest and a star with apparent magnitude of 6 is the dimmest

Factors such as surface, surface, size, and distance manipulated the brightness of the star

Name of star Distance in light years

Sirius 9Canopus 98

Alpha Centauri 4.3Arcturus 36

Vega 26Capella 45Rigel 900

Procyon 11Archernar 118

Beta Centauri 490

Formation of stars

Cloud of swirling gas and dust > gas and dust collect at the centres of whirlpools > collection of gas and dust: a star is formed

Nebulae- huge cloud of gases (mainly hydrogen and helium) and dust (is a result of ‘pull of gravity’ between particles)

A star is formed when the nebulae is pulled inward toward the core until it become compact. As the nebulae collapse, it starts to spin

The gravitational force increase and this cause the materials between the nebula to condense. As a result, the temperature and pressure of the gases and the dust particles at the centre increase

When the temperature reaches 15 000 oC, nuclear fusion takes place at the core of the nebula

Hydrogen atoms fuse together to form helium atoms, releasing a large amount of heat and light energy

The ball gas starts to shine and a new star is born

Death of stars

The lifespan of a star depends on its size A star with a small mass has a longer lifespan when compared to a star

with big mass Small star may finally die after more than 10 billion years Super large star may not survive more than 100 million years

Once the hydrogen fuel is used up and nuclear fusion is completed, the core of the star start to shrink. The star is said to be dying

A star will become either a white dwarf, a neutron star, and a black hole when it dies

death of a medium-sized star

If the star is less than 1.2 times the mass of the Sun, the heat generated in the core will heat up the outermost layer of the star

It cause the outer layer expand and become brighter The star will become bigger and red giant star is formed the outer layer of the star breaks up and drifts into space the core cool down and the star shrink to become a white dwarf white dwarf use helium as its nuclear fuel when it exhausted, the star will cool and finally fade into dark body

called a black dwarf

death of a large star

a star with mass of 1.4 to 3 times more than the mass of the Sun undergoes different changes from those of a medium-sized star

it expands to become a red supergiant which collapses rapidly and cause gigantic explosion called a supernova

during the explosion, the outer layer of the star is expelled into space this leaves a dense core called a neutron star the neutron star will eventually lose all its heat and become cold

death of a super-large star

the dying star expands to become a red supergiant it collapses rapidly and causes a gigantic explosion called a supernova during the explosion, the outer layer of the star is expelled into space then, it contracts ad becomes very dense (light cannot escape from it) the star is known as a black hole and will not be seen again

galaxies

group of million or billions of stars held together by gravity there are million galaxies scattered at random throughout the Universe each galaxies has its own shape, size and luminosity, and contain

different bodies galaxies can be classified according to their shapes there are three basic type of galaxies

- elliptical galaxies- spiral galaxies- irregular galaxies

characteristic of;

elliptical galaxies

has a flattened oblong shape some are almost spherical while others are very elongated there is little gas or dust in this galaxies very few new stars are formed in this galaxies consist mostly of old stars its core is bright but its edges are dim

spiral galaxies

it are disc-shaped with arm spiraling outwards it is among the brightest galaxies in the Universe the young, hot stars, dust and gases are concentrated in the spiral

arm the percentage of young stars is high contain a lot of dust and gases

irregular galaxies

do not have specific shape size can change among the smallest galaxies contain a lot of dust and gases. Also consist mostly of new star and

nebula

image of type of galaxies

Elliptical

Spiral

irregular

the Milky Way

galaxies were form from the large cloud of cold gases rotating slowly in space

on a clear night, we can see a band of light spreading across the sky. This is our own galaxies, the Milky Way

it is home to Earth and the Solar System it is a Spiral galaxy it is shapes like flat disc and has projection

the Universe

consist of matter, energy and space everything you can see around you it is unimaginably huge there are over 100 billion galaxies in the whole universe galaxies which have been spotted are located up to 10 000 million

light years apart the actual size of the Universe may be many times bigger

position of the Solar System in the Universe

- the Sun, the planets, asteroids, meteors, and moon make up the Solar System

- the Milky Way and millions of other galaxies make up the Universe- the Solar System is only one tiny part of the whole Universe

the milky way

the universe as a gift from god

all living thing depend it life to the Sun’s energy photosynthesis- plant use the energy to make food animal- get energy indirect by eating the plant Earth- solar energy warmth (help plant and animal to grow)

Solar energy (control Earth’s climate)- cloud, storm, rain, wind and drought

Human- use energy to produce electrical energy, dry clothing and kill microorganism

Moon smaller than sun – moon’s gravity effect the Earth – influences ocean and the sea – tidal changes