Astronomy - the study of objects and events in outer space

Astronomer - scientist who studies astronomy

What is the Universe?

The universe is all of space and everything in it.

It is mostly empty space!

A picture of a galaxy

The universe contains many galaxies.

Galaxies are large groups of stars, gas and dust that are held together by gravity.

There are three types of galaxies:

1. Spiral -

2. Elliptical (football shaped) -

3. Irregular -

We live in the Milky Way Galaxy.

The Earth is just one small part of this galaxy.

The Milky Way is a spiral galaxy.

The galaxies in the universe are moving farther apart.

This means that the universe is getting larger.

But how did the universe form in the first place?

Scientists explain this with a theory called the

Big Bang.

It is believed that this “big bang” happened between 10 and 20

billion years ago. It was a huge explosion that pushed material

throughout the universe.

A solar system consists of a star at the middle of severalrevolving planets.

Earth is part of a solar system.

Our solar system was formed about 5 billion years ago

when a giant cloud of dust and gas ( a nebula ) collapsed

to form the sun and the planets.

What is the future of our universe?

There are two possibilities:

1. Expansion continues; stars eventually die

2. “big crunch” - all matter pulled back to center of universe

In reality, no-one knows.