Our Universe

Billions of galaxies made up of billions of stars

Our Own Solar System

The Sun and the Planets that orbit it

The Sun – Our StarThe closest star to Earth

• Medium size • Yellow • Main Sequence Star• 150,000,000 Km (93

Million miles) away.• 4.5 - 5 billion years old• Will last about another

5 billion years• Located near the edge

of our disc shaped galaxy – The Milky Way

The Suns PlanetsCelestial bodies that orbit a star

Our Milky Way Galaxy

CometsRocky material made of gas dust and ice that orbit the

sun

MeteorsSpace Rocks known as shooting stars when they

enter the Earth’s atmosphere.Become meteorites when they hit the Earth’s surface

AsteroidsSmall rocky bodies known as minor planets

Orbit the sun mainly between Mars and Jupiter (asteroid belt)

StarsHuge bright balls of gas

What are Stars?

• Gigantic spheres of gases held together by gravity

• Generate huge amounts of energy because of nuclear reactions of hydrogen and other elements.

• Radiate electromagnetic radiation.– Light, heat and other forms of energy

• There are 100 billion stars in our own galaxy!

Stars• The Sun is the closest star

to Earth – 150,000,000 km away

• The next closest star is Proxima Centauri – 39,900,000,000,000 km away– 4.2 light years

• Stars are extremely far away!!!

• The Sun is thousands of times closer to Earth than other stars

• The Sun

• Proxima Centauri

Light YearsUnit of measurement for distances in Space

• The distance that light travels in one year.• Light travels at about 300,000 km/sec.

– 186,000 miles/sec

• One light year is equal to 9.46 trillion km (9,461,000,000,000).– 5.87 trillion miles (5,870,000,000,000)

• Light travels faster than anything else known to man.

Classifying Stars

Class Color Surface Temp.(degrees Celsius)

Elements detected

Examples of stars

O Blue Above 30,000 Helium 10 Lacertae

B Blue-white 10,000 - 30,000 Helium and Hydrogen

Rigel, Spica

A Blue-white 7,500 - 10,000 Hydrogen Vega, Sirius

F Yellow-white

6,000 - 7,500 Hydrogen and heavier elements

Canopus, Procyon

G Yellow 5,000 - 6,000 Calcium and other metals

The sun, Capella

K Orange 3,500 - 5,000 Calcium and Molecules

Arcturus, Aldebaran

M Red Less than 5,000 Molecules Betelgeuse,Antares

Hertzprung–Russel (H-R) Diagram- a graph that shows the relationship between a star’s

surface temperature and it’s absolute magnitude.

H-R DiagramAnalyze the graph!

Analyzing the H-R Diagram

Brightest Stars

Y-AxisBrightness

Dimmest Stars

Hottest Stars X-Axis Coolest Stars

Temperature

Stages of a Stars Life Cycle

Nebulas – Stellar Nurseries

• Giant clouds of gas and dust in space

• Where new stars are formed

GALAXIESLarge group of stars in space held

together by GravityClassified by Shape - Sprial/Disc, Elliptical, Irregular

Shaped

Spiral/Disc Shaped Galaxy

• Andromeda Galaxy – Large center with spiral arms traveling around it

– Ex. Andromeda Galaxy and our Milky Way Galaxy

– Our Sun is located near the edge of the Milky Way Galaxy

Our Milky Way• Sprial/Disc

Shaped Galaxy• 100,000 Light

Years Across• Black Hole at the

center• The Sun is near

the edge of our galaxy in one of the spiral arms.

Elliptical Galaxy

• M 87 Galaxy

– Massive blobs of stars that have very bright centers

– Very little gas and dust

– Contain mostly old stars.

Irregular Galaxy

• Large Megellanic Cloud

– Don’t fit into any other class.

– Have irregular shapes

– Contain mostly young stars and lots of gas

SupernovaDeath of a star by explosion

Black HolesGravity is so strong not even light can escape

Believed to be the center of most galaxies

Theories on the Origin of the Universe

How did we get here?• The Big Bang Theory – states that

the universe began with a big explosion.

• Steady State Theory - the universe has always been here and always will.

• There are many more theories

The Big Bang Theory

• Most dominant theory

• States that the universe was created from a cosmic explosion that hurled matter in all directions

• Occurred about 13-14 billion years ago

Evidence that supports the big bang

• Cosmic background radiation – radiation coming from all directions in

space, believed to be left over from the big bang.

• The observable expansion of the universe (Red Shift).– Galaxies are moving away from each

other

Spectroscopes/Spectrometers

•Used to gain information about properties of components in the Universe

•Shows differences in the elements that make up a star.

Electromagnetic Waves

• Light Waves that Astronomers can use to gain information about distances and properties of components of the universe.

Electromagnetic Waves

• Radio waves• Microwaves• Infrared waves• Visible Light • Ultraviolet waves• X-Rays• Gamma Rays• Cosmic Rays

From lowest to highest frequency (energy)

Electromagnetic Waves Research

1. Look up Electromagnetic Waves using your netbook.

2. Define electromagnetic waves3. List all the electromagnetic waves in

the electromagnetic spectrum4. Describe what each type of wave is

used for by humans.