Discovery Channel


The ‘big bang’ theory tries to explain how the Universe began
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Home

Observing Space

Introduction

Telescopes

Invisible Astronomy

Section 1.4

Section 1.5

Section 1.6

Section 1.7

Section 1.8

Section 1.9

Section 1.10

Section 1.11

Section 1.12

Section 1.13

Section 1.14

Section 1.15

Exploring Space

Introduction

Pioneers

Shuttles

Launchers

ISS

USA in Space

UK in Space

China in Space

France in Space

Russia in Space

The X-Prize

Section 2.12

Section 2.13

Section 2.14

Section 2.15

Planets

Introduction

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto

Section 3.11

Section 3.12

Section 3.13

Section 3.14

Section 3.15

Moons

Section 4.1

Section 4.2

Section 4.3

Section 4.4

Section 4.5

Section 4.6

Section 4.7

Section 4.8

Section 4.9

Section 4.10

Section 4.11

Section 4.12

Section 4.13

Section 4.14

Section 4.15

Stars

Introduction

The Sun

Sirius

Canopus

Alpha Centauri

Arcturus

Others

Section 5.8

Section 5.9

Section 5.10

Section 5.11

Section 5.12

Section 5.13

Section 5.14

Section 5.15

Comets, Meteors & Asteroids

Deep Impact Mission

Section 6.2

Section 6.3

Section 6.4

Section 6.5

Section 6.6

Section 6.7

Section 6.8

Section 6.9

Section 6.10

Section 6.11

Section 6.12

Section 6.13

Section 6.14

Section 6.15

Galaxies

Section 7.1

Section 7.2

Section 7.3

Section 7.4

Section 7.5

Section 7.6

Section 7.7

Section 7.8

Section 7.9

Section 7.10

Section 7.11

Section 7.12

Section 7.13

Section 7.14

Section 7.15

The Universe

Section 8.1

Section 8.2

Section 8.3

Section 8.4

Section 8.5

Section 8.6

Section 8.7

Section 8.8

Section 8.9

Section 8.10

Section 8.11

Section 8.12

Section 8.13

Section 8.14

Section 8.15

Eclipses

Solar Eclipse

Lunar Eclipse

Lunar Eclipse 2008

What Eclipses Have Taught Us

Significant Eclipses in History

The Blood Red Moon

Section 9.7

Section 9.8

Section 9.9

Section 9.10

Section 9.11

Section 9.12

Section 9.13

Section 9.14

Section 9.15

Amazing Facts

Section 10.1

Section 10.2

Section 10.3

Section 10.4

Section 10.5

Section 10.6

Section 10.7

Section 10.8

Section 10.9

Section 10.10

Section 10.11

Section 10.12

Section 10.13

Section 10.14

Section 10.15

Play: Comet Impact

Section 11.1

Section 11.2

Section 11.3

Section 11.4

Section 11.5

Section 11.6

Section 11.7

Section 11.8

Section 11.9

Section 11.10

Section 11.11

Section 11.12

Section 11.13

Section 11.14

Section 11.15

Space Blog

Section 12.1

Section 12.2

Section 12.3

Section 12.4

Section 12.5

Section 12.6

Section 12.7

Section 12.8

Section 12.9

Section 12.10

Section 12.11

Section 12.12

Section 12.13

Section 12.14

Section 12.15

Section 13

Section 13.1

Section 13.2

Section 13.3

Section 13.4

Section 13.5

Section 13.6

Section 13.7

Section 13.8

Section 13.9

Section 13.10

Section 13.11

Section 13.12

Section 13.13

Section 13.14

Section 13.15

Section 14

Section 14.1

Section 14.2

Section 14.3

Section 14.4

Section 14.5

Section 14.6

Section 14.7

Section 14.8

Section 14.9

Section 14.10

Section 14.11

Section 14.12

Section 14.13

Section 14.14

Section 14.15

Section 15

Section 15.1

Section 15.2

Section 15.3

Section 15.4

Section 15.5

Section 15.6

Section 15.7

Section 15.8

Section 15.9

Section 15.10

Section 15.11

Section 15.12

Section 15.13

Section 15.14

Section 15.15

Galaxies

Galaxies

A galaxy is a collection of solar masses that contains between 100,000 and 3,000 billion stars.

Galaxies are grouped together in clusters and super clusters and come in various forms.

No one knows exactly how many galaxies there are in the Universe, but our galaxy - the Milky Way - is just one of thousands, even millions.

The Milky Way is a spiral galaxy that stretches 100,000 light years in diameter and from our Earth-bound view it looks like two fried eggs back-to-back!

Spiral galaxies tend to include younger and brighter stars, whereas eliptical galaxies, which are the most common type, usually contain older stars.

Andromeda is sometimes described as our ‘twin’ galaxy, because it is about the same size, shape and age as the Milky Way.

Photos: Hubble

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