Discovery Channel


Asteroids range in size from pebbles to 934km across
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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

Stars

Arcturus

Arcturus is the brightest star in the northern hemisphere. Even though it gives off 180 times more power than the Sun, it only looks 110 times brighter because a lot of the light it emits is infra-red and invisible to the human eye.

Arcturus is about 37 light years away from us and could be a binary star, but its companion is 20 times dimmer and very difficult to see.

Arcturus takes its name from the Ancient Greek, ‘Arktouros’, which means ‘bear guard’, because it is the brightest star next to Ursa Major and Minor – the Big and Little Bears.

Photos: Science Photo Library

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