The Universe

8.8A

The Universe

The universe is all space and everything in it

Components of the Universe

• There are lots of parts of the universe:– Stars– Nebulae– Black Holes – Galaxies

And so much more!

Stars• Stars are large balls of

gas that create their own energy by fusing hydrogen atoms to create helium– The energy created by

fusing hydrogen atoms emits light and heat

Stars• Stars are all different

sizes and are made up of different elements

Stars• Binary Star: Stars that

revolve around each other, they look like they are blinking

Classifying Stars

• Stars are classified by three main characteristics: 1. Size2. Brightness (luminosity)3. Temperature

Classifying Stars

Size• Our sun is a medium size star (letter G below)

• There are stars in the universe large enough to fill our solar system

Classifying StarsTemperature• Temperature is determined by color– Blue: Hottest (20,000-50,000*C)– White (10,000*C)– Yellow (6,000*C)– Red-Orange (4,000-5,000*C)– Red: Least Hot (3,000*C)

Blue Red

Classifying StarsBrightness• Brightness depends on the

size and temperature of a star

• Brightness of a star is described in two ways– Apparent Magnitude: Brightness

seen from earth– Absolute magnitude: Real

brightness of a star from a standard distance

Hertz-Russell Diagram

• Nickname: H-R Diagram

• How does it help classify Stars?– Graphs the two most

important characteristics of stars: Absolute magnitude (brightness) and Temperature

Hertz-Russell Diagram

• Main Sequence: 90 % of all stars, it is the diagonal band in the diagram

Galaxy

• Galaxies are made up of millions of stars, gases, and dust

Galaxy

• Galaxies are held together by gravity

Galaxy

• There are 4 different types of galaxies that are classified by their shape. – Elliptical – Spiral– Lenticular– Irregular

Draw these next to the pictures in your box (not in the giant white space that is for notes)

Elliptical Galaxy

• Looks like a flattened ball

• Characteristics:– Contain billions of stars– Little gas and dust

between the stars – New stars rarely form,

mainly old stars in these galaxies

Spiral Galaxy• Shaped like they have arms

spiraled outwards (pin wheel)• This is the type of galaxy we

live in

Lenticular Galaxy

• Galaxy with a central bulge or bar in the middle

• It might also have small arms

Irregular Galaxy

• No specific shape to the galaxy• Disorganized shape

Black Holes

• Large objects that form dense gravity wells• Their gravitational pull is so strong, light

cannot escape it (hence why they are dark!)

Black Holes

• How can we see black holes:– We can’t– We observe them

by looking at the light and energy being sucked in

Black Holes

• Black holes have no volume, but infinite density!

• Videos: • http://

www.youtube.com/watch?v=3pAnRKD4raY – Pre AP

• http://www.youtube.com/watch?v=kfiU4ioZvPI