THE UNIVERSE

How it started... THE BIG BANG THEORY

At one time everything was compacted together in an extremely small, dense, ball of energy, and then 10 – 15 billion years ago something caused it to EXPLODE.

Because of this, nebulas, stars, galaxies, planets and other bodies formed.

The universe is still EXPANDING today.

Components of the Universe

NEBULA A large cloud of dust and gas where stars

are born.

Components of the Universe

Stars 4 kinds of stars

White Dwarfs Main Sequence – our Sun Giants SuperGiants

They are classified using their size and color. Our Sun is a MEDIUM sized star that gives off

a YELLOW color.

Stars Use the H–R Diagram to classify the stars

Spectral Class O B A F G K M

Things to remember about the H–R diagram Hottest stars are BLUE “Coldest” stars are RED The Sun is Yellow Oh Be A Fine Girl, Kiss Me – to remember spectral class

Spectral Class O B A F G K M

Our Sun

The sun appears so large to us because it is the closest star to Earth.

It is many thousands of times closer to Earth than any other star.

Components of the Universe

GALAXIES A large group of stars, solar systems, and

gas and dust. We live in the MILKY WAY Galaxy.

Galaxies

There are 3 types of galaxies... Spiral Galaxy

Spiral shaped; Milky Way is a spiral galaxy Elliptical Galaxy

Oval/Circular shaped; contains old stars Irregular Galaxy

No obvious shape

Milky Way Galaxy Our solar system is located on an outer arm of the galaxy.

Components of the Universe

Other celestial bodies... Asteroids Comets Satellites

An artificial or natural body that revolves around another object in space. Artificial satellite – Hubble Telescope Natural satellite – The Moon

Light Years

The Universe is so large and galaxies and objects are so far apart that scientists use Light Years to measure distances between them.

Light Years

Speed of Light is 300,000 km/second In 1 year, light can travel 9,500,000,000,000 km

OR 9.5 trillion km

The closest star to the sun is 4 light years away or 38,000,000,000,000 km away.