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- Everything physical that exists in space and time ~ all matter and engery that ever has or will exist


huge balls of gas that emit light


groupings of stars that are bound together by gravity

Why do we use a different measurement system for the universe than on Earth?

the distance of the universe is so huge

How is the "light year" designated?


How far will light travel in one light year?

9.5x10^15m ~ 10 trillion km

Astronomical Unit ~ How far?

the distance between the Sun and the Earth ~ 150 million km

Elliptical Galaxy

the stars in this galaxy form an egg like or spherical shape

What color do Elliptical Galaxies tend to appear? ~ Why?

red ~ the stars are older

What is an example of an Elliptical Galaxy?


Irregular Galaxy

galaxies that do not have a well defined shape or structure

What color are Irregular Galaxies? ~ Why?

blue ~ the stars are relitivly young

Give 2 examples of Irregular Galaxies

the Large Magellanic Cloud and the neighboring Small Magellanic Cloud

Spiral Galaxy

stars form arms that give the appearance of a spiral

What color are Spiral Galaxies? ~ Why?

blue ! the stars are relitivly young

Give 2 examples of a Spiral Galaxy

Milky Way and M83

Active Galaxy

emits a large amount of energy

Starburst Galaxy

creates new stars at a very high rate (a type of Active Galaxy) ~ 100 new stars per year

What is an example of a Starburst Galaxy?


Active Galactic Nucleolus

the center of the galaxies are black holes

How is a black hole created?

the outside of a dying star is pulled to the center of the star toward the pull of gravity


galaxies grouped together rather than spread apart

What Cluster does the Milky Way belong to?

The Local Group (5 million light years across)

Super Clusters

clusters of galaxies that come together (can be 100 million light years across)

Why can stars emit light?

at the center of most stars hydrogen is being converted into helium through a pressure called nuclear fusion, this creates a huge amount of energy

Gravitational Force

force that attracts 2 objects

What determines the amount of gravitational pull?

the larger or more mass an object has

Electromagnetic Force

holds the atom together ~ also acts between electrically charged particles

Strong Force

makes and holds protons and neutrons ~ only works on the nuclear level

Weak Force

keeps the nucleus together (has been over come by a radio active element ~ Beta decay)

Why is the energy from the nuclear fusion reactions created ?

both protons have overcome the Electromagnetic Force and the Weak and Strong Force take over

What size star is our Sun?

a medium star

How big (mass and km) is the Sun?

2x10^30 kg ~ 1.4 million km across

The Sun's light completely dominates our day because...

of it's proximity

How are stars classified?

according to thier intensity and size

What is a star's life cycle determined by?

it's size

What will the sun become when it runs out of hydrogen? ~ What part of the sun expands at this point?

a Red Giant ~ the outer layer

Past what point do Astronimers think that the sun will expand when it reaches this point?

past the Earth's orbit

Planetary Nebula

the core of a middle star will contract and become carbon and oxygen

White Dwarf

- The carbon oxygen core is still hot but not enough to produce heaver element the remaining core is the white dwarf

Super Giants

Stars that are 1.4 times larger than our sun and Huge stars and giant stars are formed from them


- Like medium stars the core of these large stars become carbon and oxygen but the size of these stars because they are so big allow nuclear fusion reactions until iron is formed ~ The forces that usually keep a star in balance or intact causes it to explode

How are Black Holes and Neutron Stars formed?

A star that has gone supernova will contract

What determines whether a star becomes a black hole or a neutron star? What kind of star becomes what?

It's size ~ huge star becomes a neutron star ~ a giant star becomes a black hole

Where is our solar system located?

on the Orion arm of the Milky Way Galaxy

What is the theory of the creation of our sun?

formed out of an interstellar cloud (between stars)

How did the planets form (in theory)

form by accretion (the clumping together of particles)

The Sun

he closest star to us - heats our planet and keeps everything alive on Earth

The core of the Sun

- Contains hydrogen and helium atoms, the temps and pressure are so great that it creates thermonuclear fusion

The radiative zone

The heat that is generated in the core transfers to the next layer

How fast is the heat transfer?

very slow

Convection zone

Heat continues to be transferred to the outer layer of the sun but it is transferred by convection


the surface of the sun that makes the sun apear to have color

How hot is the core of the sun said to be?

13,600,000 degrees Kelvin

Hot hot is the Photoshpere said to be?

6,000 degrees K


First layer of the atmosphere of the sun, it is like our troposphere


Second layer of the sun's atmosphere only can be seen during total eclipse


the planet closest to the sun

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