It all began with a Big Bang! about 14 billion years ago The Big Bang The Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine. Then it suddenly exploded. The Universe that we know was born. In a fraction of a second, the Universe grew from smaller than a single atom to bigger than a galaxy. It is still expanding today.

The Big Bang This is an impression of the early years of our Milky Way galaxy, about 12.7 thousand million years ago.

A Nebula An exploded bucket of paint? No. It‘s a picture of the Swan Nebula, a collection new born stars. They are surrounded by colorful blankets of glowing gas and an enormous cold, dark hydrogen cloud. The area of the nebula shown in this picture is 3500 times bigger than our Solar System.

What is space? In space, no one can hear you scream. This is because there is no air in space – it is a vacuum. Sound waves cannot travel through a vacuum. 'Outer space' begins about 200 km above the Earth. Space appears as a black blanket dotted with stars. Space is not empty, the openings between the stars and planets are filled with huge amounts of gas and dust.

The birth of galaxies We don’t know anything that happened during the first 300  000 years of the Universe. Millions of years passed, and the dense areas attracted material because they had more gravity. Finally, about 100 million years after the Big Bang, the gas became hot and dense enough for the first stars to form. New stars were being born 10 times as fast as now. Large collections of stars soon became the first galaxies. Telescopes now begin to find galaxies that were created about one billion years after the Big Bang. These small galaxies are much closer together than galaxies are today. Like two flames moving towards each other, galaxies combine into bigger galaxies. Our Milky Way galaxy came together in this way.

Extreme life Today, scientists are not so sure that life began on or near the Earth's surface. Everywhere we look, there seems to be life – even several kilometres underground. It may be that life began at the bottom of the oceans, where hot springs provided energy instead of sunlight. Building stones of life

Galaxies Nearly all stars belong to gigantic groups known as galaxies. The Sun is one of at least 100 billion stars in our galaxy, the Milky Way. And there are billions of galaxies in the Universe. Everywhere we look in the sky there are galaxies of different shapes and sizes. Galaxies were born only a few hundred million years after the Universe was created. A Spiral galaxy

This is a view of a collision (bumping into eachother) between two spiral galaxies, called the Antennae Galaxies

Star birth After their birth, most young stars lie at the centre of a flat disc of gas and dust. Most of this material is eventually blown away by the star’s radiation. Before this happens, planets may form around the central star. New stars are born in this galaxy, Galaxy NGC 1569

Star birth The bright dots are new born stars, comparable in mass to the Sun. The bright object, above and slightly to the right of centre, is a new massive star, much heavier than the Sun

Star death Most stars take millions of years to die. Stars heavier than eight times the mass of the Sun end their lives very suddenly. They try to keep alive by burning different fuels, but this only works for a few million years. Then they blow themselves apart in a huge explosion. a dying star called NGC 6369

The Sun is a star. Like most stars, the Sun is a ball of very hot gas that gives off huge amounts of light, heat and other radiation. There are many different types of star. Red stars are the coolest. Blue-white stars are the hottest. Yellow stars like the Sun are in-between Stars come in many sizes. The Sun is medium-sized.Some stars are much bigger and hotter than the Sun.

The Milky Way A view of our Milky Way galaxy. In the galaxy you can see a black hole,called,GRO J1655-40. The yellow star is our Sun. We live in a large spiral galaxy called the Milky Way. The Sun and its planets (including Earth) lie in this quiet part of the galaxy, about half way out from the centre. The Milky Way rotates once every 200 million years. It is made up of at least 100 billion stars, as well as dust and gas. It is so big that light takes 100 000 years to cross from one side to the other.

Asteroids – the minor planets Asteroids are small bodies made of rock that have been left over from the formation of the planets 4.5 billion years ago. They are often known as 'minor planets'. There are billions of these asteroids. This is a picture of an asteroid and its moon

Asteroid families Some asteroids are stony, some are made of metals, such as iron and nickel. Most are black-brown in colour and rich in carbon. Many asteroids belong to families. Each family has the same colour and seems to be made of the same materials. This shows how families of asteroids circle around

Meteorites Every day about 50 tonnes of rocky material from space lands on the Earth's surface. These rocks are called meteorites. Nearly all meteorites come from the main asteroid belt between Jupiter and Mars. Sometimes an entire asteroid can break apart. Many thousands of meteorites have been found on Earth. A Meteor Crater in the USA. The crater was made 49 000 years ago when a 10 000 000 tonne meteor fell on earth

Meteorites This is a meteorite from Mars. Some scientists believe it contains evidence that there is life on Mars.

The Sun is our nearest star. The Sun provides us with light and heat. It also gives out dangerous ultraviolet light which causes sunburn and may cause cancer. Without the Sun there would be no daylight, and our planet would be a dark, frozen world, with no oceans of liquid water and no life. This big ball of hot gas is 1.4 million km in diameter across, so 109 time the earth diameter. It has a mass of 2 million-trillion-trillion-trillion kilograms, it weighs as much as 330 000 Earths. About 1 300 000 Earths would fit inside the Sun. The Sun

Our nearest star This is a temperature map of the Sun. In the image bright indicates hotter plasma, dark areas cooler This big ball of hot gas is 1.4 million km in diameter across, so 109 time the earth diameter. It has a mass of 2 million-trillion-trillion-trillion kilograms, it weighs as much as 330 000 Earths. About 1 300 000 Earths would fit inside the Sun.