Christine Lee 9

The Universe and the Stars

Contents

3 The Universe

4 Gravity

5 Galaxy

6 Constellations

7 Stars

8 Nebula

9 Planets

10 How are stars born?

11 How do stars die?

12 Blue Giants

13 Red Dwarfs

14 Our Sun

15 Similarities & Differences

16 Main Sequence

17 Nuclear Fusion

18 Sun Spots, Solar Winds

19 Solar Prominences, Solar Flares

20 Death of our Sun

21 Astronomy

22 Astronomer

23 Ptolemy

24 Copernicus

25 Galileo

26 Comets, Asteroids and Meteoroids

27 How was solar system created?

28 Earth

29 Jupiter

30 References

The Universe

The Universe is a big empty space

It's continuously expanding

Has black holes, planets, stars and everything!

We still don't know exactly how and why the universe was created. Many theories are being created by physicists and astronomers. One of the theory was that when equal amounts of antimatter and matter collided, it made big explosions. But if antimatter and matter was equal, how does matter exist in our world? Some people say that there was a little bit more matter than antimatter.

Gravity

Gravity is a force that pulls something to a larger mass, which has a greater force of gravity.

This keeps the planets to orbit around the sun.

The more mass the objects have, the grater force of gravity!

Few physicists believe that gravity is the weakest force in the universe. Gravity can destroy a star, but it's actually not a strong force at all! We can jump, despite the strong force that pulls us towards the ground. The clips will stick to a magnet, off the ground.

Interesting, eh?

Galaxy

Galaxy is composed of millions of stars pulled in by gravity.

We live in Milky Way Galaxy

Milky Way spiral galaxy seen from top

Our Solar System

Milky Way GalaxyDiameter: 10 million light years approxThickness: 1.5 million light years approxOur Solar System: 3 million light years away from the centre of galaxy.

An elliptical galaxy

An irregular galaxy

Galaxy

Galaxy is composed of millions of stars pulled in by gravity.

We live in Milky Way Galaxy

Milky Way spiral galaxy seen from top

Our Solar System

Milky Way GalaxyDiameter: 10 million light years approxThickness: 1.5 million light years approxOur Solar System: 3 million light years away from the centre of galaxy.

An elliptical galaxy

An irregular galaxy

Constellations

Constellations are stars joined together to make a mythical character or animals.

Seasonal Constellations

Old Greeks used constellations to guess what season it was.

Constellations can be seen best towards Southern sky at 9pm.

Constellations near Polaris can be seen throughout the whole seasons.

Polaris doesn't change its location because it's on the linear extension of Earth's axis.

Stars

Stars are luminous objects that are made of gas.

Our Sun is a star!

There are two kinds of star brightness: Absolute Rating and Magnitude.

Absolute magnitude: Assuming that all stars are at 32.6 million light years away, the brightness measured from there.

Apparent magnitude: Brightness seen in the night sky

Nebula

Nebula : Gases (hydrogen, helium) and dusts between stars clustered in one area that looks like a cloud.

Emission NebulaReflection NebulaDark Nebula

Receives energy from a bright star in the nebula and is self-luminous.Reflects lights from nearby stars and looks bright.Dense clouds or dusts block the light from behind and looks dark.

Types of Nebula

Horsehead Nebula

Orion Nebula

Pleiades Nebula

Planet

Planet : a celestial body in space that orbits around a star (Sun).

The word planet comes from the Greek word planetes, meaning wanderer.

NamePicCharacteristicsPhysical Characteristics

MercuryNo atmosphere; big temperature differences

Density is big, size and radius small Terrestrial Planets

VenusThe brightest planet seen from Earth. Carbon dioxide atmosphere High temp.

MarsHas two polar caps on each pole

JupiterBiggest planet in our solar system.

Density is small, size and radius big. Has a ring. Jovian Planets

SaturnLeast dense planet Less than water

UranusAppears to be turquoise because of methane

NeptuneHas a black spot.

Nuclear Fusion

Nuclear fusion is a collision of two hydrogen atoms that causes it to explode

It's an important source of energy for stars because it needs to push outward to keep an equal balance between gravity.

Nothing could have existed without chemistry! Hydrogen and helium the main components of a star, is a very explosive particle. If you put a fire near them, it will explode.

Main Sequence

Main sequence: the equal balance between the force of gravity and an outward force created by nuclear fusion.

How are stars born?

Stars are born from clusters of gas and dust (nebula).

A part of nebula with greater density (gravity) gathers other dust particles into one spot.

This causes pressure to go up and hydrogen atoms collide against each other temperature increases.

When the density reaches its limit, nuclear fusion starts and extraordinary amount of energy is released.

Protostar

A protostar : like a pre-star

Our universe is mostly made of the fundamental chemical, 'hydrogen'. But we don't know where it came from.

How do stars die?

If nuclear fusion stop, the gravity takes over and the main sequence brakes down. The star starts to decrease.

Stars with 8~30 times of our Sun's mass slowly die by creating heavier elements such as oxygen and iron...then it explodes when the pressure is too high for a star.

Stars with 30+ times of our Sun's mass becomes a black hole when it dies.

Blue Giants

Blue giants are huge stars with high temperature

Burns up hydrogen quicker than red dwarfs dies earlier than red dwarfs.

Red Dwarfs

Red dwarfs are small stars with lower temperature.

Lasts longer than blue giants.

Our Sun

Our Sun is in between a blue giant and red dwarf.

Orange and medium-hot temperature.

The Sun's core can be as hot as 15 million degrees Celsius ! The surface temperature is about 6000 degrees Celsius.

The Sun uses more than 30 million truck loads of fuel every second!

Similarities & Differences

Blue GiantsRed DwarfsOur Sun

PicTemp20 000 40 000 C2000 5000 C6000 C

Magn.-6+16+5

Other factsA star

Lifespan is short

Blue

Humongous

A lot of gas

A star

Lifespan is long

Red

Small

Less gas

A star

Lifespan is medium long

Orange

Medium

In the middle

Sun Spots, Solar Winds

Sun spots are cool, dark spots on Sun.

Solar winds are caused by electrically charged particles called ions, emitted into space.

Solar Wind. SHhhhhhh~~~

Can you see the little dots on here? It's about 10 times bigger than the earth!

Solar Prominences, Solar Flares

Solar prominences : a gas loop on Sun's surface.

Solar flares are 'magnetic storm' on the Sun. It is the bright spots on the Sun and releases highly charged particles. That means its explosion is huge!

Gigantic solar flares cause satellite and communication problems

Solar prominence seen from an eclipse.

Death of our Sun

Our sun is mostly likely to die by running out of helium and hydrogen.

Won't happen until next billion years

Astronomy

Astronomy is the study of our universe, stars and things beyond our planet Earth.

* Pluto is not in our solar system anymore.

Astronomer

Astronomer is a person who studies astronomy.

Being an astronomer is not easy. You have to handle complicated machines and telescopes. You also need to be accurate with math! Calculating distances and brightness takes a lot of time to calculate.

Ptolemy

Ptolemy was a Greek astronomer. In AD 150, he published an encyclopedia of ancient science with details of the movements of the planets.

He believed that the universe was geocentric, therefore the Earth was centre of everything and the universe.

The Church liked his geocentric idea. Science and religion seemed to fit perfectly well together- the fact that the God created 'us' and that the Earth was the centre of our universe.

Copernicus

Nicolaus Copernicus was a Polish astronomer.

He published De revolutionibus orbium coelestium 'On the Revolution of the Celestial Spheres', which claimed that the sun was at the centre of the universe.

Heliocentric

Copernicus, however, suggested that the Sun was in the centre. The church disliked this because this theory would break apart science and religion.

Galileo

Galileo Galilei was an Italian scientist who took a telescope in 1609 and discovered that Jupiter had 4 moons revolving around Jupiter.

In 1632 he published Dialogue Concerning the Two Great World Systems, criticizing the Ptolemaic system.

He was warned by the Church to stop spreading his heliocentric ideas.

Comets, Asteroids and Meteoroids

AsteroidsCometsMeteoroids

Small rocks between Mars and Jupiter. Shape and sizes are irregular.Ice melts near Sun and the long 'tail' faces the opposite of the Sun.Rocks that burn and produce light because of friction on Earth's atmosphere.

How was solar system created?

The Rotating Nebula Theory:A supernova : birth of our Sun

Dusts and gases circles around the sun, which has the most gravity

Heavier elements circles closely to the sun and lighter elements (gases) is pushed to the outer part of the solar system.Heavier elements collide onto each other and they kept getting biggerTerrestrial Planets

Lighter elements orbited around from far distanceGaseous Planets

Earth

Terrestrial Planet

One day Is not 24 hours... it's actually 23 hours 56 minutes and 4 seconds

Is mostly made of iron, oxygen and sillicon

The only planet that...Organisms can live

Has water and land

Ozone layer / atmosphere

TOP SECRETThis information must be sealed from aliens incase they try to invade the Earth!

Jupiter

Gaseous Planet

Biggest planet in the solar system

One day in Jupiter is 9 hours 55 minutes and 30 seconds

Has 4 big moons

Callisto

Ganymede

Europa

Io

References

O2 (a Korean Science Workbook), Middle School Grade 2 first semester. ISBN 978-89-6416-023-7

Wikipedia : definition of 'Planet'

Read and Understand Science: Grades 4-6+. Heidrich, Delana.

http://www.universetoday.com/14382/10-interesting-facts-about-planet-earth/Viewed on December 22nd, 2010

The Dangerous Book for Boys. Iggulden, Gonn and Hal.

B.C Science Probe 9. Ledrew, Barry.

I Wonder Why : Big Book Of Knowledge. ISBN 0-7534-1187-3

George's Secret Key To The Universe. Hawking, Lucy and Stephen.

The Live Science Textbook 2 (Korean). ISBN 89-5862-092-7

http://www.enchantedlearning.com/subjects/astronomy/sun/prominences.shtml.

http://www.nasa.gov/multimedia/imagegallery/image_feature_1560.html

http://blog.naver.com/dhfk8022?Redirect=Log&logNo=40117865004

Viewed on December 13, 2010.