justthefactssolarsystem-viny.pdf

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JUST

THE

FACTS

SOLARSYSTEM

S

choolSpecialtyPublishing INFORMATION AT YOUR FINGERTIP


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SOLAR

SYSTEM


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CONTENTSHOW TO USE THIS BOOK .............................................................................................................................4

OUR HOME IN SPACE ......................................................................................................................................... 6 The Solar System History of the solar system Our Changing Views Some Space Units Orbits and Eccentricity Wrong Impressions

EARLY ASTRONOMERS.....................................................................................................................................8 Hipparchus of Rhodes Ptolemy of Alexandria Nicolaus Copernicus Tycho Brahe Johannes Kepler Astronomical discoveries timeline

LATER ASTRONOMERS ........................................................................................................10 Galileo Galilei Giovanni Domenico Cassini John Flamsteed Edmond Halley William Herschel Edwin Hubble Percival Lowell Steven Hawking Space Sciences Astronomical discoveries timeline

THE SUN ......................................................................................................................................................................... 12 Where in the solar system? Star Profile Structure and layers Flares andprominences Solar wind Photosphere Sunspots Sun timeline

MERCURY ..................................................................................................................................................................... 14

Where in the solar system? Planet profile Orbit details Surface conditions Major features Other geological features Small and curious Distinguishing features Temperature Spin Transit of Mercury Mercury timeline

VENUS .............................................................................................................................................................................. 16 Where in the solar system? Planet profile Orbit details Surface conditions Major features Other geological features Transit of Venus Daytimeviewing Reverse spin Nearest neighbor Circular orbit One long day Under pressure Venus timeline

EARTH ............................................................................................................................................................................... 18 Where in the solar system? Planet profile Orbit details Surface conditions Major features Other geological features Plate tectonics Polar ice Life Earth timeline

THE MOON.................................................................................................................................................................. 20 Where in the solar system? Moon profile Lunatics Orbit details Origin Surface conditions Major features Other geological features Near and Far Phases of the Moon The Moon and Tides Eclipses Moon timeline

MARS ................................................................................................................................................................................. 22 Where in the solar system? Planet profile Orbit details Surface conditions Major features Mars maps and physical features Martians! Mars timeline

JUPITER ........................................................................................................................................................................24 Where in the solar system? Planet profile Orbit details Atmosphericconditions Major features Other features Moon records

Jupiters rings True giant Jupiters moons Speed spin Jupiter timelineSATURN........................................................................................................................................................................... 26 Where in the solar system? Planet profile Orbit details Atmosphericconditions Major features Other features Main moons Titan The rings of Saturn Vast but light Saturn timeline

URANUS ........................................................................................................................................................................... 28 Where in the solar system? Planet profile Orbit details Atmosphericconditions Major features Other features Main moons On its side Ringsof Uranus Odd little world Uranus timeline

NEPTUNE ....................................................................................................................................................................... 30

Where in the solar system? Planet profile Orbit details Atmosphereicconditions Major features Other features The first paper planet Naming

Neptune Voyager visit Neptunes rings Size and shape

PLUTO .................................................................................................................................................

Where in the solar system? Planet profile Orbit details Is Pluto a true planet? Many names Plutinos Smalles Odd orbit Pluto timeline

ASTEROIDS.................................................................................................................................. Asteroid facts Asteroid types The trojans Where do a First discoveries Strangest asteroids Asteroids with moo Space probes to asteroids

METEORS ........................................................................................................................................

Meteorite facts Meteors Craters Meteor showers Ty The Ten Biggest Meteorites Parent Comets Best Meteor

COMETS............................................................................................................................................

Comet facts The structure of a comet Famous comets Where do comets come from? Comet orbits Comet hist

Some space probes to cometsSTARS..................................................................................................................................................

Star brightness Names of stars Stars together Bright Colors and hotness Closest stars Birth and death of a s

STAR CONSTELLATIONS ..........................................................................................

How many constellations? Finding names Orion Signs Largest constellations Smallest constellations Brightest

TELESCOPES ............................................................................................................................... The worlds biggest telescope Types of light Telescope telescope Making sharp images Space telescopes Link Telescopes of the future Telescope timeline

MILKY WAY................................................................................................................................

Size and shape Galaxy profile Age of the Milky Way Many arms Speeding stars Nearest galaxies In a spin

GALAXIES......................................................................................................................................

Galaxy names Galaxy shapes Active galaxies How ga How many galaxies Farthest galaxies Largest local g

THE UNIVERSE .......................................................................................................................

Cosmology Dark matter Expansion of the universe N The Big Bang The future of the universe Cosmologist

HUMAN BEINGS IN SPACE ................................................................................

Apollo crews Vostok Gemini Mercury Apollo SoyuSPACE PROBES ...................................................................................................................... Sputnik Pioneer Venus probes Vikings to Mars Rece 10 Early Moon probes

LIVING IN SPACE ...............................................................................................................

Salyut Space Stations Skylab Mir International Space

GLOSSARY...................................................................................................................................

INDEX ..................................................................................................................................................

This edition published in the United States in 2006 by School Specialty Publishing, a member of the School Specialty Family.

Copyright ticktock Entertainment Ltd 2006 First published in Great Britain in 2006 by ticktock Media Ltd. Printed in China.

All rights reserved. No part of this book may be reproduced, stored in a central retrieval system, or transmitted in any form or by

any means, electronic, mechanical, photocopying, recording, or otherwise, withouth the prior written permission of the publisher.

Written by Steve Parker.

Library of Congress-in-Publication Data is on file with the publisher.

Send all inquiries to:

School Specialty Publishing

8720 Orion Place

Columbus, OH 43240-2111

ISBN 0-7696-4259-4

1 2 3 4 5 6 7 8 9 10 TTM 11 10 09 08 07 06


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Jupiter is by far the biggest planet in the solar system. It is a vast planet

of swirling gases and storms of unimaginable fury. As the fifth planet

out, it is the nearest gas giant, a planet made almost completely of

gases, to the Sun. It is not much smaller than some of the stars called browndwarfs. Jupiter does not shine itself, but reflects sunlight as all planets do.

Even so, its huge pull of gravity holds more than 60 moons in orbit around it.

Jupiter is named after the Roman king of the gods, also called Jove.

JUPITER

Jupiter has more than twice asmuch mass than all the other eightplanets added together. However,it would probably need to be 50times heavier to start burning likea true star.

Jupiter is not only the largest

planet, it also spins around the

fastest, once in less than 10 Earth

hours. The spinning speed of the

upper atmosphere at the equator is

5 minutes faster than at the poles,

so the atmosphere is continually

being twisted and torn.

MAIN RING DustfromAdrasteaandMetis moons.

FIRST GOSSAMER RINGDustfrom Thebemoon.

SECOND GOSSAMER RINGDustfrom Amaltheamoon.

FAINT OUTER RING

On January 711, 1610, Galileo discovered Jupiters four mainmoons, now known as Galilean moons, by following their orbitsacross the face of the planet.

This was direct evidence that the Earth was not at the center of everything. Italso strengthened his idea that planets like Earth and Jupiter probably revolvedaround the Sun.

M OO N ( or g ro up ) D IA ME TE R D IS TA NC E FR OM J UP IT ER

Inner group F ou r s ma l l mo on s L es s t ha n 1 36 ,7 02 m i le s

lessthan125milesacrossIo 2 ,2 63 mi le s 1 24 ,2 80 mi le s

Europa 1 ,1 93 9m il es 2 62 ,0 44 mi le s

Ganymede 3 ,2 70 mi le s 6 64 ,8 18 mi le s

Callisto 2 ,9 95 mi le s 1 ,1 69 ,4 75 mi le s

Themisto 4 .9 7m il es 4 ,5 92 ,1 46 mi le s

Himaliagroup Mostunder62.14miles 6.87.5milllionmiles

Ananke group Mo stu n der62.14miles 13m i ll ion m i les

Carmegroup Mo stu n der62.14miles 14m i ll ion m i les

Pasipha Smal lo u termos tmo on s 14mi ll ion m i les

Average distance from Sun483.6million miles

Average distance from Sun5.203AU(Earth =1)

Closest distance to Sun(perihelion)460.27million miles

Farthest distance from Sun(aphelion)507.12million miles

Average orbital speed8.07miles per second

Slowest orbital speed7.7milesper second

Fastest orbital speed8.5milesper second

Time for one orbit(Jupiter year) 11.87Earth years

Axial rotation period(Jupiter day)9.92Earthdays

Jupiter has severaldistinctive features mappedby astronomers.

Great Red SpotAgiantstorm systemthreetimeswiderthanEarth, thattravelsaroundJupiterjustsouthof theequator,once every6 days.

White SpotSmallercirculatorystorm systemsinJupitersatmosphere,aboutthesizeof Earth.

Browns SpotsStormyregionsthatare probablywarmerthansurroundingclouds.

RingsTheseconsistof dustknockedfromJupitersmoons bymeteorstrikes.

Inner StructureCentralsmallrockycore, thenalayerofmetallichydrogen,thenliquidhydrogen,and finallytheoutermostatmosphereof mainlyhydrogengas. Theselayersflowfromone toanother,withno sharpboundaries.

Jupiters Giant Red Spot.

3,000years agoJupiterwasknown toGreeksand thentheRomans.

1,500years agoInAncientChina, Jupiterwasknown as

the WoodStar.

1610GalileoobservedJupitersfour largestmoons.

1665TheGreat RedSpot wasfirst observed.

1690GiovanniDomenicoCassininoticed thattheupperatmospheretakes longertospinatthepolesthanaroundtheequator.

1973US Pioneer10probeflew past.

1979Voyager1 flewpast takingspectacular

photographs.Voyager2achievedsimilarresults.

1992Ulyssesprobepassesby Jupiteronits

wayto theSun,taking measurements.

1994Partsof cometShoemaker-Levy9hit

JupiterinJuly,photographedby theapproachingGalileospaceprobe.

1995Galileobecamethefirst probeto orbit

JupiteronDecember 7.On thesameday,anatmosphereprobe ithadalreadyreleasedparachuted94milesintothe atmosphere,collectinginformationfor almostone hour.

19962003Galileocontinueditsstudiesof Jupiterandits nearermoons,flying pastmanyofthem severaltimes.

2000TheGreatRedSpothadshrunktoabouthalfitssizein1900.

2000CassiniprobepassesonwaytoSaturn.

2003Galileoplungedintothe cloudsinSeptember.

2007The NewHorizons probeisdueto flypast,onitswayto Pluto.

2010TheUS JupiterprobeJunoisscheduledforlaunch. Junowillorbit overJupiters

poles.

J U P I T E R

TIMELINE BELTSStrips of dark clouds that wind from west toeast (left to right) and change through the years.

ZONES Lengths of light-colored clouds that changelike the darker belts. Blue-tinted clouds are the lowestand warmest. Zones contain higher clouds than belts.

TURBULENCE Belts sometimes move in the oppositedirection to their neighboring zones, creating swirlingpatterns of storms and turbulence along their edges.

- Ganymede is the largest moonin the solar system.

- Callisto is the most heavilycratered object.

- Io probably has the mostvolcanic activity.

NASAimagesshowing IOvolcanoesproducered-and black-coloredlavaflowsand yellowsulphurpatches.

Seepage55 forinformationonprobes toJupiter.

ATMOSPHERE:

Mostlyhydrogen, some helium,tracesof methane,water vapor,ammonia,hydrogensulphide, andother gases

NATURE OF SURFACE:

Visible surface iswhirling gases,possiblya solidsurface ona small rockycore miles below visible surface

AVERAGE CLOUD-TOP

SURFACE TEMP: -202F

LOWEST CLOUD-TOP

SURFACE TEMP: -261F

HIGHEST CLOUD-TOP

SURFACE TEMP: -277F

WEATHER OR CLIMATE:

Complete cloudcoverage withstormsandwind speedsup to 272.84 mph.

SEASONAL CHANGES:

Few,being so far from Sun

A shot ofJupiters atmosphere.

WHERE INTHE SOLAR SYSTEM?

ATMOSPHERIC CONDITIONS

PLANET PROFILE MAJOR FEATURES

Diameter at Equator 88,850 miles

Surface area 33.7 billion sq miles

Tilt of axis 3.13

Mass (Earth = 1) 318

Volume (Earth = 1) 1,236

Overall density 1.33 g per cm3

Gravity (Earth = 1) 2.36

Number of moons more than 60

ANASA photographof Jupiter.

ORBIT DETAILS

Sun

Jupiter

OTHER FEATURES

MOON RECORDS JUPITERS RINGS

TRUE GIANT JUPITERS MOONS

SPEED SPIN

GossamerRigs

A ma lt he a A dr as te a Metis

MainRing

GossamerRings

Amalthea Adrastea Metis Thebe

Halo

HOW TO USE THIS BOOK

JUST THE FACTS, SOLAR SYSTEM is a quick and easy-to-use way to look up facts about our

solar system. Every page is packed with cut-away diagrams, charts, scientific terms and key pieces

of information. For fast access to just the facts, follow the tips on these pages.

TWO QUICK WAYS

TO FIND A FACT:

Look at the detailed CONTENTS list on

page 3 to find yourtopic of interest.

Turn to the relevantpage and use the BOX HEADINGS to find theinformation box you need.

Turn to the INDEXwhich starts on page60 and search for key words relating toyour research.

The index will direct you to the correct page,and where on the page to find the factyou need.

GLOSSARY A GLOSSARY of words used in this book begins on

The glossary words padditional information to s

the facts on the main p

JUST THE FACTSEach topic box presents thefacts you need in short,easy-to-follow information.

67 Our Home in Space 5859 Glossary

LINKS

Look for the purple links throughout the book. Each link gives detailsof other pages where related or additional facts can be found.

INTRODUCTION TO TOPICBOX HEADINGSLook for heading words linked to yourresearch to guide you to the right fact box

SCIENTIFIC DIAGRAMSClear, accurate diagrams explaindifficult astronomic concepts.

TIMELINESImportant events are listedin chronological order.

For fast access to facts in thlook for key words in the he

1992Ulysses probe passes by Jupiter on itway to the Sun taking measurement

See page 55 forinformation on probes to Jupiter.

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GLOSSARY


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The Solar System is based aroundthe Sun, our nearest star, at thecenter.

- It is comprised of nine planets that goaround, or orbit, the Sun. They are(listed in order from nearest to theSun) Mercury, Venus, Earth, Mars,Jupiter, Saturn, Uranus, Neptune, andPluto.

- All of these planets, except for Mercuryand Venus, have orbiting objects, calledmoons.

- Smaller space objects, calledasteroids,orbit in the wide gap between Marsand Jupiter.

- Similar smaller space objects, calledKBOs (Kuiper Belt Objects), orbit in awide region beyond Neptune, called theKuiper Belt.

- Objects called cometsoccasionally enterour solar system.

- The limit of the solar system is usuallytaken as the orbit of the outermostplanet Pluto.

- Some experts disagree that Pluto is atrue planet. Others search for moreplanets.

- There are regular announcements ofthe 10th planet, as in 2003 and2005. Most people continue torecognize the nine for now.

Space is so gigantic that ordinary Earth units like miles andpounds are far too small for convenient use.

Astronomical unit (AU)The average distance from the Earth to the Sun is 93 million miles..Light year (l-y)The distance that light (which has the fastest and most constant movement in theuniverse) travels in one year, is5.88 trillion miles.

Parsec (pc)19.2 trillion miles, defined by a stars apparent shift in position (parallax) when viewedfrom two points which are a distance apart equal to the distance from the Earth to theSun, that is, one AU.

Axial tiltThe angle at which the axis, the imaginary line around which a planet spins, is tiltedcompared to the level of the solar plane.

Most orbits, especiallythose of the planetsaround the Sun, are notexact circles.

- They are shaped more likeellipses or ovals.

- The Sun is not in the center ofthe oval of most orbits, butslightly offset toward one end,near one of the points calledthe focus.

- The amount that a planetsorbit differs from a circle iscalled eccentricity.

- The bigger the eccentricity, themore elliptical the orbit.

Planet Eccentricity

Mercury 0.205

Venus 0.006

Earth 0.016

Mars 0.093

Jupiter 0.048

Saturn 0.054

Uranus 0.047

Neptune 0.008

Pluto 0.248

Venus has the most circular orbit,closely followed by Neptune,while Plutos is the most ovalorbit, followed by Mercury.

Beliefs about the solar system anduniverse have constantly evolved.

- In ancient times, people thought all objectsseen in the skies went around Earth.

- Gradually, scientific observations showedthat Earth and other planets orbited theSun.

- The invention of the telescope around1609 confirmed this idea and allowed thediscovery of many more space objects.

- From the 1930s, astronomers realized thatsome space objects gave out invisible radiowaves, as well as or instead of light rays.

- Radio telescopes allowed discovery of yetmore objects in space, many invisible toordinary optical telescopes, because theygive out no light.

- More kinds of rays were discovered comingfrom space objects.

- From 1990, the Hubble Space Telescopehas discovered more stars and other spaceobjects.

OUR HOME IN SPACE

Acity may seem like a big place. But most cities are tiny compared to whole

countries. Many countries are small compared to continents, and all the

continents together cover less than one-third of Earth. So, when we try to

imagine that Earth is one of the smaller planets in the vastness of the solar system, it is

very difficult. Solar system science attempts to understand incredible distances, sizes, and

forces. Even then, the solar system is just one microscopic speck among the star clusters

of our galaxy, the Milky Way, which is only one galaxy among billions of others.

In solar sy

almost imp

idea of dist

an ordinary

- The planet

the Sun. E

would fit in

1,000 tim

- The four in

close to th

become ev

farther from

- Diagrams

biggerm clcloser toge

just to fit t

Planet

S

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto

The Suplanets i

The solar system probably began to formabout 5,000 million years ago.

- A vast cloud of space gas and dust began to clumptogether under its own pull of gravity. The clumpbegan to spin.

- The center of the clump became the Sun.- Much smaller bits spinning around it became the

planets and perhaps some moons.

- Most of the solar system, including Earth, wasformed by 4,500 million years ago.

- The solar system is probably only about one-thirdas old as the universe itself.

THE SOLAR SYSTEM

HISTORY OF THE SOLAR SYSTEM

SOME SPACE UNITS

ORBITS ANDECCENTRICITY

WRONGOUR CHANGING VIEWS

Sun

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto


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8

EARLY ASTRONOMERS

The earliest astronomers were not interested in how the universe

worked, but when to plant or harvest crops and when rivers would

flood. They used the movements of objects in the skies to make

calendars, and to predict events in the future. Consequently, they became

astrologers as well as astronomers. It was the ancient Greeks who first started

to ask questions about the universe and how it worked. Their work was

followed by the studies of great European astronomers from the 15th century

onward.

Lifetime: 14731543

Nationality: Polish

Major Achievements:

Copernicus realized the geocentricsystem dating back to Ptolemywas inaccuarate.

He devised a new heliocentric,meaning Sun-centered system.Copernicus stated that the Earthand all the other planets revolved

around a stationary, central Sun.

Copernicus ideas wereincorporated in his book TheRevolution of the HeavenlySpheres, completed in 1530.

The book was not published until1543, perhaps just a few daysbefore he died.

HIPPARCHUS OF RHODES

Lifetime: Between 190120 BC

Nationality: Greek

Major Achievements:

H ipparchus was believed to have cataloged over 800stars. He also studied the motions of the Moon.

He invented a brightness scale, subsequentlydeveloped by later generations of astronomers into

a scale referred to as magnitude.

Hipparchus calculate d the length of the Earths yearto within 6 1/2 minutes.

The Greek astronomer Ptolemy.

Lifetime: AD 87150

Nationality: Greek

Major Achievements:

Ptolemy wrote many books containing Greek ideas and

observations collected over the past 500 years, includingAlmagest, also called the Greatest.

Ptolemy described more than 1,000 stars in his books,including 48 different constellations.

The astronomer also made early calculations of the size anddistance of the Sun and Moon.

Ptolemy devised a geocentric system with Earth at thecenter of the universe. His order for closest to farthest fromEarth was the Moon, Mercury, Venus, Sun, Mars, Jupiter,and Saturn.

A bronze statue of Tycho Brahe in Prague.

Lifetime: 15461601

Nationality: Danish

Major Achievements:

Brahe discovered a supernova inCassiopeia in 1572, now calledTychos Star. He suggested thiswas a star outside the solarsystem that did not move.

Brahe plotted the accuratepositions of 780 stars over20 years.

The astronomer employedJohannes Kepler as his assistant tohelp him with his studies.

Kepler completed and published Brahesstar cataloge, Rudolphine Tables, in1627.

Lifetime: 15711630

Nationality: German

Major Achievements:

Kepler joined Brahe in Prague in 1600 ashis assistant.

He devised the laws of planetary motion,linking a planets orbit and speed to the Sun.

The astronomer wrote the first astronomytextbook, Epitome AstronomiaeCopernicanae (Epitome of CopernicanAstronomy).

The German astronomer Johannes Kepler.

27,000 years agoFirst stone age rock carvings of theSun and Moon.

5,000 years agoEgyptians introduce a year with365 days, which proceeded ourmodern calendar.

4,500 years agoMars known by the Egyptiansas the Red One.

4,300 years agoChinese make first record of solareclipse.

4,000 years agoBabylonian priests made some ofthe first records of astronomical

observations.3,500 years agoVenus known to Babylonians.

2,455 years agoAnaxagoras of Ancient Greecesuggested the Sun was madeof hot rocks.

2,360 years agoChinese astronomers may havespotted the moons of Jupiter.

2,265 years agoAristarchus proposed the Sun wasthe center of the solar system.

2,000 years agoJupiter and Saturn knownto Greeks and Romans.

1,855 years agoPtolemys view of the solar system,based on Aristotles belief that theEarth was the center of the solarsystem, begins to dominate beliefsfor 1,400 years.

1543

Copernicus revived thesuggestion of Aristarcus.

1608Lippershey invented the opticaltelescope.

1609Galileo began his space studies.

1609Kepler published his first lawsof planetary motion.

A S T R O N O M I C A L

D I S C O V E R I E S

TIMELINE

1610Galileo Gaamoons of Jup

1619Keplers thirdmotion.

1632An official oup in Leiden

1665Dutch astronHuygens disc

1671Giovanni Cathe moon of

1672Britains Royestablished

1687Newton pubexplaining lagravitation.

1705Halley correcseen in 168

1781William Herseventh plan

1796Laplace puborigin of the

1801Giuseppe Piaasteroid, Cer

1814Johann Galland John Addiscovering planet in the

1846Neptune dis

1923Hubble showgalaxies outsmoving apa

1931Clyde Tombaninth planet

The Polish astronomerNicolaus Copernicus.

The title page and an illustrationfrom Brahes Rudolphine Tables,

completed by Kepler.

TYCHO BRAHE

An illustration of the early astonomer Hipparchus.

A S T R O

D I S C

TIM

See page 40 MAGNITUDE

HIPPARCHUS OF RHODES

PTOLEMY OF ALEXANDRIA

NICOLAUS COPERNICUS

TYCHO BRAHE

JOHANNES KEPLER


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AstronomyGeneral study of objects inspace including the stars,planets, moons, andgalaxies. Often includesobserving and recording.

AstrophysicsThe physical nature of stars,planets, and other spacebodies, including their make-up and contents, temperaturesand pressures, and densitiesand conditions.

CosmologyStudy of the origins, history,make-up, and fate of theuniverse as a whole. Oftencarried out usingmathematics and physics,rather than stargazing.

Space scienceOften more concerned withspacecraft, probes, rocketsand other hardware, and theconditions for spacetravellers.

10

LATER ASTRONOMERS

Lifetime: 15641642

Nationality: Italian

Major Achievements:

Galileo improved the firsttelescopes and was the firstperson to use them forscientific studies of thenight sky.

He observed mountains andcraters on the Moon, manystars too faint to see with theunaided eye, and four ofJupiters moons.

Galileo recorded his earlydiscoveries in his book SiderealMessenger(1610).

Galileobelieved in Copernicusideas that the Sun, not theEarth, was the center of thesolar system, as had been

previously stated by Ptolemy. He put forward both sets of

theories in his book Dialogueon Two Chief World Systems(1632). This work was heavilycriticized and the astronomerwas put under house arrest byreligious leaders for his views.

Galileo made advances inmany other areas of scienceincluding the mechanics ofmoving objects, like swingingpendulums, falling canonballs,and bullets.

After the telescope was invented, many more people began looking at

the night sky. Some had little science background, and did it as a

hobby, but chanced upon an amazing discovery that put their name

forever into history. Others were full-time professional astronomers who spent a

lifetime observing and recording, yet their names are known to very few. Even

now, millions of people watch the skies every night.

See page 8 for information on PTOLEMY.

Lifetime: 16461719

Nationality: British

Major Achievements:

Flamsteed became the firstAstronomer Royal in 1675.

He made the first extensive star charts

using the telescope as part of work

aimed at giving sailors a better method

of navigation. The charts recorded the

positions of over 2,935 stars.

Due to a dispute with Isaac Newton

and the Royal Society, the charts were

published six years after he died.

Lifetime: 18891953

Nationality: American

Major Achievements:

Working mostly at Mount Wilson

Observatory, Hubbles studies of

nebulae, such as parts of Andromeda,

showed they were masses of stars.

Hubble concluded that these star

masses were galaxies outside our own

Milky Way.

He introduced a system of classifying

galaxies by their shapes.

Hubble measured the speed of

galaxies in 1929 and showed farther

ones move faster, leading to Hubbles

Law and the idea that the universe is

expanding.

Lifetime: 17381822

Nationality: German-British

Major Achievements:

Herschel made many of his owntelescopes.

He discovered the planet Uranusin 1781 and some moons ofUranus and Saturn.

During his lifetime, Herschelcataloged over 800 double-stars.

He also published a chart of over5,000 nebulae in 1820.

Herschel also recognized that theMilky Way was a flattened disc ofstars.

Lifetime: 16251712

Nationality: Italian-French

Major Achievements:

Cassini was appointed as Director of theParis Observatory in 1669.

He made many discoveries, including

four satellites of Saturn and the gap

in Saturns rings,now named the Cassini

Division.

Cassini made many advances combining

his observations with calculations,

including the orbit times of Mars, Venus,

and Jupiter, the paths of Jupiters

moons, and the first fairly accurate

distance between the Earth and theSun (the AU, Astronomical Unit).

Lifetime: 1940

Nationality: British

Major Achievements:

Hawking continued Einsteins ideason time being a fourth dimension,and worked on the origin of theuniverse at the Big Bang.

He worked on a common theoryfor the four basic forces in theuniverse, being gravity,electromagnetic, and strong andweak nuclear forces.

Hawking made great advances toour understanding of black holes.

Lifetime: 16561742

Nationality: British.

Major Achievements:

Edmond Halley traveled to St.Helena in the South Atlantic at theage of 20 to make the firsttelescopic chart of stars as seen inthe Southern Hemisphere.

Halley became interested incomets after the Great Cometof 1680. He worked out fromhistorical records that a comet

seen in 1531, 1607, and 1682should return in 1758, which itdid (now called Halleys Comet).

The astronomer was the first tosuggest that nebulae were cloudsof dust and gas where stars mightform.

Halley became Astronomer Royalin 1720 and began an 18-yearstudy of the complete revolutionof the moon.

Halleys other activities includedstudying archaeology, geophysics,and the history of astronomy.

Lifetime: 18551916

Nationality: American

Major Achievements:

Lowell became interested in astronomy

after reports by Schiaparelli of channelson Mars. Channelswas misunderstoodascanals, and Lowell became convincedof the existence of Martians, evenwriting books on them.

He established the Lowell Observatoryin Arizona in 1894, mainly to studyMars.

Lowell predicted the existence ofanother planet beyond Neptune(eventually discovered Pluto in 1930 atLowells observatory).

1931First radio t

1948200-inch Hfirst operateCalifornia.

1962First X-rays

1963First quasardiscovered.

1967First pulsar star) discove

1976

240-inch reoperated atUSSR.

1986Halleys com

1987SN1987Absupernova tunaided eye

1990Hubble SpaEarth orbit bDiscovery.

1991The probe Gwithin 16,0asteroid Ga

1992COBEsatellitechoes of

2001Genesis retusolar wind.

2004Hubble Utrafirst galaxiedark agesmillion year

2005Deep Impacdevice into

2005Astronomersdiscovery olargest objesolar system

A S T R O

D I S C

TIM

SPACE SCIENCES

GALILEO GALILEI

GIOVANNI DOMENICO CASSINI JOHN FLAMSTEED

EDMOND HALLEY

WILLIAM HERSCHEL EDWIN HUBBLE

STEPHEN HAWKINGPERCIVAL LOWELL


8/36

THE SUN

Our closest star, the Sun, is the center of the solar system. All the

planets and asteroids are held in their orbits by its immense gravity.

It also attracts objects from the f arthest reaches of the solar system,

such as comets. For billions of years, the Sun has been providing Earth with

light that green plants use as an energy source for living and growing.

Herbivorous animals eat the plants, and carnivorous animals eat the herbivores.

In this way, the Sun powers life on Earth.

12

Solar wind steams away from the

Sun in all directions.

It reaches speeds of up to 250

miles per second and comes

mainly from the corona.

Solar wind consists of charged

particles, ions, and other particles

in a form called plasma.

Where it interacts with Earths

magnetic fields, near the North

and South Poles, it creates an

aurora, shimmering light high in

the sky, calle the Northern Lights

(Aurora Borealis) and Southern

Lights(Aurora Australis).

Sunspots are cooler variablepatches on the photosphere,probably caused by magneticinteractions. The inner umbra of each spot is

around 7,232F. The outerpenumbra is about 9,932F.

They were first noticed to vary in aregular way by Heinrich Schwabebetween 1826 and 1843.

Sunspots usually vary in an11-year cycle. An average sunspotlife is 2 weeks.

On March 30, 2001, SOHO(Solarand Heliospheric Observatory)recorded the largest sunspot groupso far, covering more than 13 timesthe area of the Earth.

NASA photo of a sunspot.

Corona 35.6 million F Surface 10,000 F Core 27 million F

Solar flares are massiveexplosions in the lower coronaand chromosphere.

They were first observed byRichard Carrington in 1859.

Trigger massive solar eruptionscalled coronal mass ejections.

Solar prominences are largerand longer-lasting than flares.

Many leap up, along, and down

in a curved arc back to the Sun.

Typically, prominences arethousands of miles long.

Largest ones are 310,000 ormore miles long.

Average distance from center

of Milky Way 26,000 light years

Time for one orbit around

center 225 million years

Average orbital speed

135 miles per second

Time for one revolution

25.38 days at equator

Diameter at Equator 864,938 miles(109 time Earths)

Surface area 109109

sq miles

(12,000 times Earth)

Mass 2x1027

tons(333,000 times Earth)

Volume 33 x 1016

cubic miles(1.3 million times Earth)

Overall density 99 lbs. per square foot


Number of main planets 9 (debated)

27,000 yeDepicted in Europe, NorAustralia.

From 7,00Sun worshipmany ancie

4,900 yearFirst phase oStonehenge,stone-age te

From 4,00The Sun woancient Egyp

2,030 yearChinese astrmentioned s

AD 1300sAztec peopletheir Sun go

1610Sunspots firstelescope byFabricius, th

1962McMath PieArizona is ladedicated to

1990Ulysses probspace shuttleNorth and Sstudied sola

1995Joint Europ ewas launche

1997ACE (AdvanExplorer) sastudy particl

the Sun and2001Space probelaunched onsamples of t

2004On Septembreturned butcrash-landin

2005Preliminary from Genesi

TIM

A diagram of solar wind. The Earth is protected by its magnetic field.

Close-up of a sunspot.

Carbon

Oxygen

Helium

Hydrogen

Traces

Key

See pages 11 and 54SOLAR WIND

A NASA photographof the Sun.

CORE

About 174,000 miles across.

Nuclear fusion reactions convert hydrogen to

helium, producing immense amounts of light,

heat, and other radiation.

Energy output equivalent to Earths largest

power plants do in a year, every second.

RADIATIVE ZONE

About 220,000 miles deep.

Conveys heat and light outwards by photon

transfer between ions.

Temperature falls with distance from the core.

CONVECTIVE ZONE


Super-hot material carries heat outwards from

radiative zone.

Material cools at photosphere and sinks back

to receive more heat.

The result is in-and-out convection currents.

PHOTOSPHERE

Visible surface of the Sun.

Varies in depth from 621 miles.

Emits photons of light and other energy forms

into space.

CHROMOSPHERE


Visible as a red-colored flash around the Sun

at the start and end of a total solar eclipse.

CORONA

Wispy outer atmosphere around the Sun.

Extends many millions of miles into space,

to distances bigger than the Sun itself.

Prominence

Photosphere

Chromosphere

FilamentCorona

Convective Zone

Radiative ZoneCore

Sunspot

73.5%

24.8


ORBIT DETAILS

STAR PROFILE

STRUCTURE AND LAYERS

FLARES ANDPROMINENCES

SOLAR WIND

SUNSPOTS

MAKE-UP OFPHOTOSPHERE

0.7 0.3 0.7%

TEMPERATURES


9/36

ATMOSPHERE:

Almost zero, traces of potassium,argon, oxygen, and argon

NATURE OF SURFACE:

Bare iron-rich rocks pitted withhundreds of large craters

AVERAGE SURFACE

TEMPERATURE: 338F

LOWEST SURFACE

TEMPERATURE: -275F

HIGHEST SURFACE

TEMPERATURE: 840F

WEATHER OR CLIMATE:

None due to lack of atmosphere

SEASONAL CHANGES:

None due to almost zero tilt of axis

14

5,000 yearThe Sumeriawhom they c

3,300 yearEarliest detaMercury in a

2,500 yearIn ancient GVenus) was tdifferent plaApolloin theHermes at d

2,470 yearHeraclitus thalong with Vrather than t

1,000 yearAncient Chin

to Mercury a1639Giovanni Zuobservationsparts of Merdifferent time

1965Radar measMercury doethree times f

1973USMariner 3 to fly past

1974Mariner 10Venus in Febin March of about two-fisurface.

1974Mariner 10

1975Mariner 10ssends informa

196162TheMercuryseat craft waastronauts in

2004USMercurylaunched in

200809Messengerdflybys of Me

2011Messengerdorbit in Maryear to study

M

TIMMERCURY

Mercury has several featuresthat distinguish from otherplanets.

Mercury has several hundred namedcraters, with names likeShakespeare, Mark Twain, Dickens,Beethoven, Chopin, Degas, andSibelius. All of its craters are namedafter famous artists and classicalmusicians.

Less than half of Mercuryssurface has been mapped inany detail, so its surfacefeatures are less knownthan most other planets.

SCARPS (RUPES) Long cliff-likeridges with one steep side and one

gradually sloping side.

RIDGES (DORSA) Long,prominent ridges with two steep

sides, formed as Mercurys core

cooled, shrank, and the already solid

crust cracked into wrinkles.

YOUNGER PLAINS Uplandsprobably formed from hardened

lava flows, less marked by craters

from impacts.

OLDER PLAINS Lowlands muchmore pockmarked with overlapping

craters than the younger plains.

ARECIBO VALLIS Valleynamed after the AreciboObservatory, home of Earths largestradio telescope, in Puerto Rico.

ICE Despite Mercurys incredibleheat, there is probably ice at itsNorth Pole, in deep craters withpermanent shade from the Sun.

Mercury is the second-smallest

planet in the Solar System,

after Pluto.

It has a very oval-shaped orbit,

much more than most other

planets. Only outermost Pluto is

more eccentric.

Its axis is hardly tilted at all, so

the Sun is always directly over

its equator all through its year.

The size of Mercuryis shown in the above pictureof the planet (circled in red)

travelling past the sun.

SMALL AND CURIOUS

Caloris BasinMassive crater made byasteroid/meteoroid impact,measuring 800 miles across.

Caloris MontesCurved ranges with peaks risingto 9800 feet sited at one of thehottest places on Mercury,

within th e Caloris Ba sin crater.

Discovery ScarpJoining two craters, this cliffis 217 miles long and itsmaximum height is around9,200 feet.

See pages 3437for information on ASTEROIDS

and METEORS.

The heavily pitted CalorisBasin crater.

In 1974, the Mariner 10spacecraft produced this image of

the 27 mile wide Degas crater.

A NASA photograph ofthe planet Mercury.

Mercury has the widesttemperature range of any planet,spanning almost 1112F betweenday on the sunny side and nighton the shady side. Earthsmaximum range is less than300F.

Since Mercury is closer to the Sunthan Earth, when the two planetsare almost in line, Mercury appearsto cross the Sun when viewedfrom Earth. This is called the transitof Mercury.

Because of its closeness to the Sunand slow spinning speed, at certainplaces and times on Mercury theSun will rise just over the horizon,then go back and set, and thenrise againall on the sameMercury day.

Average distance from Sun35,980,000 milesAverage distance from Sun0.387 AU (Earth =1)Closest distance to Sun(perihelion) 28,580,000 milesFarthest distance from Sun(aphelion) 69.8 million kmAverage orbital speed29.5 miles per second

Slowest orbital speed24.1 miles per secondFastest orbital speed36.6 miles per secondTime for one orbit(Mercury year) 87.9 Earth daysAxial rotation period(Mercury day) 176 Earth days

PLANET PROFILE

Known by most ancient people by its brief periods of visibility at

dawn and dusk, Mercury was named after the Roman winged

messenger of the gods. It has the fastest orbital speed of any planet,

averaging 30 miles every second. Being the closest planet to the Sun, it is

blasted by solar heat and other radiation. This has an extremely weak

atmosphere. Mercurys daytime side heats to incredible temperatures, however,

the night side plunges to within -275F.

Diameter at Equator 3032 miles

Surface area 75 million sq km

Tilt of axis 0.01Mass (Earth = 1) 0.055

Volume (Earth = 1) 0.056



Number of moons 0

A color photograph of Mercuryshowing the pitted iron-rich surface.

Sun Mercury


SURFACE CONDITIONS


ORBIT DETAILS

OTHER GEOLOGICAL FEATURES SMALL AND CURIOUS

DISTINGUISHING FEATURES

TEMPERATURE SPINN ING MERCURY MERCU RY TRANS IT

NorthGiant Crater

South Polar Ices

SouthGiant Crater

CraterKuiper

CraterKuiper

NorthGiant Crater

North Polar Ices

A NASA photograph ofMercurys ice caps.

Aug. 23, 1991 Feb. 21, 1994


10/36

ATMOSPHERE:

Thick, dense, mainly carbon dioxide,also nitrogen, and sulphur acids

NATURE OF SURFACE:

Hard and rocky, numerous volcanoes

AVERAGE SURFACE

TEMPERATURE: 878F

LOWEST SURFACE

TEMPERATURE:

113F (at cloud tops)

HIGHEST SURFACE

TEMPERATURE:

932F in valleys near the equator

WEATHER OR CLIMATE:

Thick swirling deadly-poisonous

atmosphere, winds are 186 mph near

its top

SEASONAL CHANGES:

Minimal on surface due to dense

atmosphere

16

3,600 years agAstronomical rappearances o

3,500 years agAncient Babyloof the brightest

2,500 years agIn ancient Greetwo different plPhosphorus in tat dusk.

2,000 years agAncient Chinesas the Metal St

1610Galileo observ

1639

First transit of V1672Giovanni Domdiscover moon

1961Russian space p

Venus, but faile

1962US probe Mar

1966Venera 3probsurface. Venera

year and sent 6, and 7also s

1970Venera 7made

1975Venera 9was picture back froOctober 21.

1978US sent two Pio

1990

The Magellan pof the surface.

199899Cassini-Huygen

2004First of a pair o

2006European Spacorbiter probe is

2012Next transit of

VENUS

Venus, the second planet from the Sun, is named after the Roman

goddess of love and is shrouded in mystery. It is covered by thick

swirling clouds of poisonous gases and droplets of acid that hide its

surface from the view of outsiders. Although Venus is about the same size

and mass as Earth, it could not be more different. It is the hottest of all the

planets, partly because its thick atmosphere traps in vast amounts of heat

from the nearby Sun in a greenhouse effect far more extreme than on Earth.

Ishtar TerraNorthern highlands about the sizeof Australia, bearing Venusshighest mountains.

Maxwell MontesMaxwell Mountains, a rangeabout 540 miles long, with thehighest peaks over 7 miles tall.

Lakshmi PlanumVast upland plain partly encircledby Maxwell Mountains.

Aphrodite TerraSouthern uplands, roughly thesize of South America.

Arachnoid VolcanoesPhotographed by the space probeMagellan, these have unusualridges around them. The central

volcano with its surroundingridges looks like a giant spider.

Several probes have beensent to Venus, and radiowaves have been used to

map virtually the entireplanet.

A NASA photograph of the sprawlingAphrodite Terra, shown in brown.

Because of its closeness andbright reflection of sunlight, Venusis so bright that it is one of onlytwo space bodies, other than theSun, which can be seen duringdaylight from Earth. The otherbody is the Moon.

It is also often the first star-like

body to appear at dusk and thelast to fade at dawn, earning itthe names Evening StarandMorning Star.

Venus is one of only three planetswith retrograde spin (the othersare Uranus and Pluto). This meansit spins on its axis in the oppositedirection than the other planets.Seen from the side, its surfacemoves from east to west or rightto left, or clockwise if viewed fromabove its North Pole.

No other planet comes closer tothe Earth than Venus. At its closest,it is 23.7 million miles away.

Venus takes longer to spin once onits axis than to complete one orbitof the Sun.

A NASA mosaic ofthe planet Venus.


Surface area 460 million sq km

Tilt of axis 177.36

Mass (Earth = 1) 0.815




Number of moons 0

Average distance from Sun67,240,000 miles

Average distance from Sun0.723 AU (Earth =1)

Closest distance to Sun(perihelion) 66,780,000 miles

Farthest distance from Sun(aphelion) 67,690,000 miles

Average orbital speed21.7 miles per second

Slowest orbital speed21.6 miles per second

Fastest orbital speed21.9 miles per second

Time for one orbit(Venus year) 224.7 Earth days

Axial rotation period(Venus day) 117 Earth days

Magellan radar image of thevolcano Sif Mons on Venus.

The transit of Venusacross the Sun.

TIM


SURFACE CONDITIONS


ORBIT DETAILS

Sun

Venus

OTHER GEOLOGICAL FEATURES

TRANSIT OF VENUS

DAYTIME VIEWING REVERSE SPIN

UNDER PRESSURE

The atmospheres pressing force orpressure on Venus (pictured belownext to the Earth) is incredible90 times more than our own, andequivalent to the pressure almost3,280 feet under the sea onEarth.

CIRCULAR ORBIT

Most planets have an orbit that is

an ellipse. The journey of Venus

around the Sun is the most circular

of all planets, meaning it has the

least eccentric orbit of all the

planets (especially compared to

Mercurys).

NEAREST NEIGHBOR

ONE LONG DAY

Since Venus is closer to the Sun than Earth, when the twoplanets are almost in line, Venus appears to cross the discof the Sun when viewed from Earth. This is called thetransit of Venus. The date it occurs and the time thatVenus takes to cross the Suns face have been used toestimate the distance between Earth and the Sun. Transitsoccur in pairs. The two in each pair are about eight yearsapart, but the time between pairs is more than 100 years.

See page 18 forinformation on the Earths orbit.

CORONAE Circular centers surrounded byring-like ridges, the largest being Artemis Coronaat 1,300 miles across.

PLAINS Flat and fairly smooth, these cover two-thirdsof the surface with low volcanoes up to 124 milesacross.

MOUNTAINS Six main mountain ranges cover aboutone-third of the surface.

UPLANDREGION One of the largest is Beta Regio,about 3,280 feet deep.

LOWLAND DEPRESSIONS Wide and low, includeAtalanta Planitia, Guinevere Planitia, and Lavinia Planitia.

ALL FEATURES All of Venuss surface features arenamed after females, either real people or from mythand legend, except Maxwell Mountains, named afterscientist James Clerk Maxwell.

The Maxwell Mountains shot using radar.


11/36

18

EARTH

Human beings may think of Earth as an average planet, but the

more we learn about the rest of the solar system, the more we see

that Earth is very unusual. This is mainly because its average

surface temperature is just above 71F. Earth has the smallest range of

surface temperatures of any planet. Also, more than three-quarters of Earths

surface is rivers, lakes, seas, oceans, and frozen water as glaciers and ice-

caps.

RiversThe Amazon River of South Americacarries more water than the next five

biggest rivers combined, emptying6,350,000 cubic feet per second intothe Atlantic Ocean.

OceansThe Pacific Ocean covers almost half(46%) of the Earths surface.

MountainsThe Himalayas of central Asia andnorthern India have eight of the

worlds ten tallest peaks.

DesertsThe Sahara Desert of North Africais by far the greatest arid (very dr y)area, covering more than 3.5 millionsquare miles.

Lowest PointThe bottom of the deep-seaChallenger Deep in the north-west

Pacific Ocean is 35,840 feet belowthe oceans surface.

Highest PointThe peak of Mount Everest in the

Himalayas is 29,035 feet above sealevel.

Earth has been mappedextensively.

Earths highest mountain, Everest.

A NASA photographof Earth.


Surface area 196.9 million sq miles

Tilt of axis 23.4

Mass 6.6 sextillion tons

Volume 259.8 billion miles3


Gravity 1g (9.8 miles per second 2)

Number of moons 1

Average distance from Sun92.9 million miles

Average distance from Sun1.0 AU

Closest distance to Sun(perihelion) 91.4 million miles

Farthest distance from Sun(aphelion) 94.5 million miles




Time for one orbit(Earth year) 365.256 Earth days

Axial rotation period(Earth day) 23.93 Earth hours

ATMOSPHERE:

Almost four-fifths nitrogen, one-fifthoxygen, traces of carbon dioxide, watervapor, and other gases

NATURE OF SURFACE:

Varied from high rocky mountains todeep valleys and trenches, mostlycovered with water

AVERAGE SURFACE

TEMPERATURE: 71.6F

LOWEST SURFACE

TEMPERATURE: -130F

HIGHEST SURFACE

TEMPERATURE: 140F

WEATHER OR CLIMATE:

Varies due to movement of atmosphere

and its water vapor distributed by clouds

and falling as rain, generally conditions

become colder from the equator to the

poles

SEASONAL CHANGES:Marked seasons due to considerable

tilt of axis, from cold winters and

hot summers.

PrehistoryMore than 10made maps ofstone or ivory,woven into ha

3,000 years aEarly Greeks bflat disc.

2,500 years aIn Ancient Grethe world wasobservations sat different pla

15191522Ferdinand Mathe globe to shsphere.

1785James Hutton UniformitarianEarths surfacehuge lengths oprocesses we volcanoes, eabuilding, and and snow. Heimmeasurably

1862William Thomage from its coapproximate atenth of today

1908Frank Taylor dexplanation fo

1912Alfred Wegenthe modern thwhich causes

1956Clair Pattersonof radioactivity4,500 million accepted age million.

1960sScientists camebasic ideas anversion of pla

1989The first of thesatellites was l1990s would Positioning SyEarths surface

Apart from large cloud systems, the glistening ice caps over the North and

South Poles are perhaps Earths most noticeable feature from space.

Each shrinks in summer, then spreads in winter, due to Earths seasonal

changes and zoned climate from the equator to the poles.

The Arctic ice cap over the North Pole is a piece of ice up to 33 feet thick

floating in the Arctic Ocean, with a winter extent of 9.3 million sq miles.

The Antarctic ice cap over the South Pole covers the vast southern land

mass of Antarctica, with a winter extent of 11.8 million sq miles.

Researchers believe that theEarths outer surface of thinrocky crust, is split into 1215giant curved pieces calledlithospheric plates.

Over millions of years, theseslidearound the globe, at therate of about 1-3 cm per ye ar,carrying the major land masseswith them in a process calledcontinental drift.

At the edges of some platesnew rock is added by a processcalled seafloor spreading.

Where two plates ram into eachother, the crust buckles intomountains, such as theHimalayas and Andes.

Where one plate slides belowthe other there are earthquakesand volcanoes.

TIM LAKE SUPERIOR is the largest body of freshwater by area.

LAKE BAIKAL is the largest body of fresh waterby volume.

THE LAMBERT GLACIER on Antarctica is thelargest glacier, at 311 miles long and 50 miles wide.

THE GRAND CANYON, the most spectaculardeep valley, has been worn away by the ColoradoRiver. It is 277 miles long, up to 18 miles wide, andin places, 1 mile deep between almost sheer cliffs.

THE GREAT BARRIER REEF is a long series ofrocky reefs built over thousands of years by billi ons oftiny animals called coral polyps.The outer reef of the Great Barrier Reef.

Earth is the only planet in the solarsystem known to support life. This lifedepends on liquid water, which occurs in

the narrow temperature range of 32to 104F.

The greatest variety of land lifeoccurs in tropical rainforests, which

have 9 out of 10 of the

more than 20 million species of plants,animals, and other life-forms.

The richest variety of marine life is foundin coral reefs.

Many areas of wildlife are beingaffected, polluted, and used foragriculture and industry by the dominantlife-form on Earth, human beings.

Other 1%

Nitrogen 78%

Oxygen 21%


SURFACE CONDITIONS


ORBIT DETAILS

Sun

Earth

OTHER GEOLOGICAL FEATURES

PLATE TECTONICS POLAR ICE

LIFE


12/36

20

THE MOON

The Moon turns around once inthe same time it takes to goaround the Earth once.

This means that it keeps thesame side facing Earth.

Due to the Moons slightvariations in orbit, almost three-fifths of its surface is visible

from Earth. The other two-fifths is always

hidden and has only been seenby spacecraft in lunar orbit.

The far side is sometimes calledthe dark side of the Moon, but itreceives sunlight in the samepattern as the near side.

Tides are the regular rising and fallingof the surface of the oceans. Althoughthe Sun has some influence, oceantides are mainly caused by thegravitational interaction between theEarth and the Moon. The gravitationalpull from the Moon causes the oceansto bulge in the direction of the Moon.Another bulge occurs on the opposite

side, since the Earth is also beingpulled toward the Moon and away

from the water on the far side. Sincethe Earth is spinning on its axis, tidesrise and fall twice a day, with the

interval between low and high tidebeing just over six hours.

An artists illustrationof the Moon.

Average distance from Earth238.866 miles

Average distance from Earth0.0026 AU (Earth = 1)

Closest distance to Earth(perigee) 225,630 miles

Farthest distance from Sun(aphelion) 252,101 miles




Time for one orbit(Earth units) 29 days 12 hours44 minutes

Axial rotation period(Earth units) 27 days 7 hours43 minutes

Amoon, also called a satellite, is a natural object of reasonable size

going around a planet. The one human beings call theMoon is

Earths single moon. It has also been known to scientists asLuna.

The word luna comes from the Latin word for moon. Seen from Earth, the

Moon is about the same size as the Sun. It appears to change shape during its

29.5-day orbit because we can only see the sunlit part of its surface, creating

the phases of the Moon. Its pull of gravity also makes the water in seas and

oceans rise and fall, calle tides.



Tilt of axis 1.5





Number of moons None

ATMOSPHERE:Tiny traces of helium, neon, hydrogen, and argon

NATURE OF SURFACE:Craters, mountains, valleys, and plains, called seas

AVERAGE SURFACE TEMPERATURE:-9.39F

LOWEST SURFACE TEMPERATURE:-382F

HIGHEST SURFACE TEMPERATURE: 250F

WEATHER OR CLIMATE: None

SEASONAL CHANGES: None

Largest CraterThe largest known crater in the solarsystem, the South Pole-Aitken Basin is1,398 miles across and 8 miles deep.

Sea of Tranquility

The site for the first ApolloMoonlanding in 1969. 373 by 559 miles.

Sea of SerenitySite for the last Moon landing in 1972,about 342 miles wide.

Sea of CrisesMain dark circular area near the topedge, as seen from Earth.

Apennine MountainsPeaks more than 14,764 feet high.

CopernicusSmall crater (below) but 9,843 feet deep.

Ocean of StormsLargest lowland plain, covering2.3 million sq miles.

The moon has been visited and mapped several times.

1959Russian spaceinto the surfacehuman-made world. Next mthe Moon andof the previous

1966Luna 9soft-lanfirst close-up imsurface.Luna to go into Moo

1966The first of thetouched downmore than 11,

1968In December, UMoon orbit, bu

back to Earth landings later.

1969Apollo 11 touccarrying the fiworld. Neil Aout of the Lunasurface, followAldrin. Michathe command

1969Apollo 12lan

studies in Nov

1971Apollo 14coll

rocks in Febru

1972Apollo 16coll

of Moon mate

1972Eugene Cerna

step on the Mo

1994The Clementin

information thbe frozen wate

2003European spa

2004In February, P

announced pla

Moon mission

2004Smart 1 entere

November 15

surface using

T

TIM MARIA Meaning seas, these are dark lowland plainsof hardened basalt rocks which once flowed as lava.They are totally dry, like the rest of the Moon, andoccur mainly on the near side.

MARE Dark lowland plains of hardened basalt rocks.

RILL an ancient lava channel, such as the Hyginus Rilland the Hadley Rill.

NAMES Most lunar features are named after famousscientists, especially astronomers.

The barren surface of the Moon.

The heavily pittedCopernicus crater.

It is thought the Moon was formed when ahuge piece of rock the size of Mars,crashed into Earth around 4.5 billion yearsago. Earth was about 100 million yeas oldat the time. The loose matter and debrisorbiting Earth after the impact cametogether to form the Moon.

See page 55 for informationon MOONPROBES.

The Moon features greatly in manylegends and stories. One superstitionwas that if a person stared at the

full moon for too long, he or shewould become mad. This is wherethe word lunaticcomes from.Another legendwas that at fullmoons, certainpeople wouldgrow hair, longteeth, claws, andbecome savage anddeadly werewolves.

The Sun lights up only half the Moon at a time. As the Moon movesaround the Earth, we see varying amounts of the sunlit half of theMoon. This causes it to show changes of shape, calledphases.

When the Moon is between the Sun and the Earth, its dark side is turned toward us, andnormally, we cannot see it. This is called the New Moon. As the Moon moves around theEarth, the sunlit side begins to show. First we see a thin crescent, then a Half Moon, andthen a Full Moon. At Full Moon, all of the sunlit side faces us. After Full Moon, the phaseslowly decreases to half and back to a crescent as we see less and less of the sunlit side.

Finally, it is New Moon once again. The time from one New Moon to the next New Moonis 29.53 days.

Solar eclipseWhen the Moon comes betweenthe Earth and Sun and blocksout part, partial eclipse, or all,total eclipse, of the Sun. Theamount of the Sun blocked outvaries with the position on

Earth. The area of shadow onEarth of a total eclipse is 270km wide and moves across theEarth as the Earth spins and theMoon continues its orbit. Onaverage, there are 2 totaleclipses every 3 years.

Lunar eclipseWhen the Earth comes betweenthe Sun and Moon. The Moonseems to fade, but stays acopper-red color, due to sunlightrays bent around the edge ofthe Earth by the atmosphere.

Sun

Sun

Sun

Spring tides


ORBIT DETAILS

MOON PROFILE LUNATICS

ORIGIN MAJOR FEATURES

SURFACE CONDITIONS

OTHER GEOGRAPHICAL FEATURES

NEAR AND FAR PHASES OF THE MOON

THE MOON AND TIDES

First Quarter

Moons pull

Earth

Suns pull

Third quarter

Moons pull

First Quarter

Moons pull

Earth

Suns pull

Moons pull

Third quarter

Moons pull

Moons pull

Full

New

Earth

Suns pull

Suns pull

Moons pull

NewMoon

Suns pull

Moons pull

Suns pull

Earth

FullMoon

ECLIPSES

Waning Crescent Full Moon First Quarter

Last Quarter W an in g G ibbous W axin g G ibbous W axin g Cresc en t


13/36

22

Named after the Roman god of war, Mars is also called the Red Planet,

because its surface rocks and dust contain large amounts of the

substance iron oxide, also known as rust. Like Earth, Mars has polar ice

caps, volcanoes, canyons, winds, and swirling dust storms. Features resembling

river beds and shorelines suggest that great rivers, probably of water, once flowed

across Mars surface. Despite many visits by space probes, landers, and rovers,

there are no signs of life.

MARS

CYDONIA MENSAE (the face)

Natural landform resembling a giant face

First photographed by Viking 1 on 7/25/76

Image represents an area 2.2 miles by 1 mile

VALLES MARINERIS A vast canyon

2,500 miles long

4 miles deep in places

See page 19THE GRAND CANYON

THARSIS THOLUS Partially buried volcano

100 mile diameter crater

ARSIA MONS Largest crater in

Tharsis Montes

75 mile diametercrater

ELYSIUM PLANITIA Second largestvolcanic region

1000 miles by1440 miles

OLYMPUS MONS Largestvolcano insolar system

Nearly 15miles high

Taller thanthree Mt. Everests

Very flat typicalslopes 2 to 5

THARSIS MONTES Largest volcanic region

2,400 miles across

6 miles high

12 large volcanoes

A NASA photographof Mars.


Average distance from Sun1.52 AU (Earth = 1)





Fastest orbital speed26.5 m per second

Time for one orbit(Mars year) 686.9 Earth days

Axial rotation period(Mars day) 24.62 Earth hours



Tilt of axis 25.1





Number of moons 2

ATMOSPHERE:

Mostly carbon dioxide, small amounts of

nitrogen and argon, traces of oxygen,

carbon monoxide, and water vapor

NATURE OF SURFACE:

Rocks and dust, including giant volcanoes,

deep canyons, and dusty plains

AVERAGE SURFACE TEMPERATURE:

-81.4F

LOWEST SURFACE TEMPERATURE:

-220F

HIGHEST SURFACE TEMPERATURE:

68F

WEATHER OR CLIMATE: Clouds, fog,

strong winds, dust storms, and a red sky

SEASONAL CHANGES:

Marked (similar to Earth) with intensely

cold winters.

A photograph of the surface of Mars

taken by the Viking lander.

North Polar Cap

Water ice that remainsthrough summer.

Sand dunes formed by wind.

North polar cap is about680 miles across.

South Polar Cap

The polar frost containsfrozen carbon dioxide.

Carbon dioxide freezes ataround -193F.

South polar cap is about260 miles across.

April 2000

January 2001

4,000 years aAncient EgyptiMars.

3,000 years aThe BabyloniaStar of Death.

1610Mars is studiedtelescope.

1877Giovanni Schiand written stumoons were d

1964Mariner 4is thand returned w

1969Mariners 6an

175 close-up Russian probe

1971Mariner 9toopicture of the

1976US Vikings 1 aAugust, carrie

1997Mars Global Sorbit and still o

1997Mars PathfindSojourner, exp

1999The US Mars Polar Lander rboth fell silent.

2001US Mars OdyMars orbit andof scientific inf

2003European Mar

its Beagle 2la

2004Mars exploratOpportunity toto explore the back a wealth

2005Spiritand Oppexplore and se

2020Proposed end missions carry

TIM

Giovanni Schiaparellis studies of Mars in 1877 usedthe term canali, meaning channels, which could benaturally occurring.

Some people took this to mean canalsmade by someadvanced life-form, like on Earth.

Percival L owell developed the idea to suggest Martiansdug canals to take water from the planets ice-caps towater their crops, since other areas on Mars changedcolor with the seasons.

The myth of Martians began, and H. G. Wellsfeatured their invasion of Earth in War of theWorlds in 1898. It continues to be populartoday.

The channels are now known to beimagined or perhaps long-drywatercourses, and the color changesare probably dust storms.

See pages 55 for informationon space probes to Mars.


SURFACE CONDITIONS


ORBIT DETAILS

Sun

Mars

MARS MAPS AND PHYSICAL FEATURES

MARTIANS!


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24

Jupiter is by far the biggest planet in the solar system. It is a vast planet

of swirling gases and storms of unimaginable fury. As the fifth planet

out, it is the nearest gas giant, a planet made almost completely of

gases, to the Sun. It is not much smaller than some of the stars called brown

dwarfs. Jupiter does not shine itself, but reflects sunlight as all planets do.

Even so, its huge pull of gravity holds more than 60 moons in orbit around it.

Jupiter is named after the Roman king of the gods, also called Jove.

JUPITER

Jupiter has more than twice asmuch mass than all the other eightplanets added together. However,it would probably need to be 50times heavier to start burning likea true star.

Jupiter is not only the largest

planet, it also spins around the

fastest, once in less than 10 Earth

hours. The spinning speed of the

upper atmosphere at the equator is

5 minutes faster than at the poles,

so the atmosphere is continually

being twisted and torn.

MAIN RING Dust fromAdrastea and Metis moons.

FIRST GOSSAMER RINGDust from Thebe moon.

SECOND GOSSAMER RINGDust from Amalthea moon.

FAINT OUTER RING

On January 711, 1610, Galileo discovered Jupiters four mainmoons, now known as Galilean moons, by followin g their orbitsacross the face of the planet.

This was direct evidence that the Earth was not at the center of everything. Italso strengthened his idea that planets like Earth and Jupiter probably revolvedaround the Sun.

MO ON ( or g roup ) D IA ME TE R D IS TAN CE FR OM JU PI TER

Inner group Four small moons Less than 136,702 milesless than 125 miles across

Io 2,263 miles 124,280 miles

Europa 1,1939 miles 262,044 miles

Ganymede 3,270 miles 664,818 miles

Callisto 2,995 miles 1,169,475 miles

Themisto 4.97 miles 4,592,146 miles

Himalia group Most under 62.14 miles 6.87.5 milll ion miles

Ananke group Most under 62.14 miles 13 million miles

Carme group Most under 62.14 miles 14 million miles

Pasipha Small outermost moons 14 million miles







Fastest orbital speed

8.5 miles per second

Time for one orbit(Jupiter year) 11.87 Earth years

Axial rotation period(Jupiter day) 9.92 Earth days

Jupiter has severaldistinctive features mappedby astronomers.

Great Red Spot

A giant storm system three timeswider than Earth, that travelsaround Jupiter just south of theequator, once every 6 days.

White SpotSmaller circulatory storm systemsin Jupiters atmosphere, about thesize of Earth.

Browns SpotsStormy regions that are probably

warmer than surrounding clouds.

RingsThese consist of dust knocked fromJupiters moons by meteor strikes.

Inner StructureCentral small rocky core, then alayer of metallic hydrogen, thenliquid hydrogen, and finally theoutermost atmosphere of mainlyhydrogen gas. These layers flowfrom one to another, with no sharpboundaries.

Jupiters Giant Red Spot.

3,000 years aJupiter was knthe Romans.

1,500 years aIn Ancient Chithe Wood Sta

1610Galileo observmoons.

1665The Great Red

1690Giovanni Domthe upper atmospin at the polequator.

1973US Pioneer 10

1979Voyager 1 flewphotographs.similar results.

1992Ulysses probe way to the Su

1994Parts of cometJupiter in Julyapproaching G

1995GalileobecamJupiter on Decday, an atmosalready releasinto the atmosinformation fo

19962003Galileocontinand its nearer of them severa

2000The Great Redhalf its size in

2000Cassiniprobe

2003GalileoplungeSeptember.

2007The New Horipast, on its wa

2010The US Jupiterfor launch.Junpoles.

J

TIM BELTS Strips of dark clouds that wind from west toeast (left to right) and change through the years.

ZONES Lengths of light-colored clouds that changelike the darker belts. Blue-tinted clouds are the lowestand warmest. Zones contain higher clouds than belts.

TURBULENCE Belts sometimes move in the oppositedirection to their neighboring zones, creating swirlingpatterns of storms and turbulence along their edges.

- Ganymede is the largest moonin the solar system.

- Callisto is the most heavilycratered object.

- Io probably has the mostvolcanic activity.

NASA images showing IO volcanoesproduce red- and black-colored lava

flows and yellow sulphur patches.

See page 55 forinformation on probes to Jupiter.

ATMOSPHERE:

Mostly hydrogen, some helium, tracesof methane, water vapor, ammonia,hydrogen sulphide, and other gases

NATURE OF SURFACE:

Visible surface is whirling gases,possibly a solid surface on a small rockycore miles below visible surface

AVERAGE CLOUD-TOP

SURFACE TEMP: -202F

LOWEST CLOUD-TOP

SURFACE TEMP: -261F

HIGHEST CLOUD-TOP

SURFACE TEMP: -277F

WEATHER OR CLIMATE:

Complete cloud coverage with stormsand wind speeds up to 272.84 mph.

SEASONAL CHANGES:

Few, being so far from Sun

A shot ofJupiters atmosphere.






Tilt of axis 3.13

Mass (Earth = 1) 318

Volume (Earth = 1) 1,236



Number of moons more than 60

A NASA photographof Jupiter.

ORBIT DETAILS

Sun

Jupiter

OTHER FEATURES

MOON RECORDS JUPITERS RINGS

TRUE GIANT JUPITERS MOONS

SPEED SPIN

GossamerRigs

A mal th ea A dr as te a Metis

Main Ring

GossamerRings

Amalthea Adrastea Metis Thebe

Halo


15/36

ATMOSPHERE:

Mostly hydrogen, small amount of helium,

traces of methane, water vapor, and ammonia

NATURE OF SURFACE:

Visible surface is whirling gases, possibly

a solid surface on a rocky core miles below

visible surface

AVERAGE CLOUD-TOP SURFACE

TEMPERATURE: -202F

LOWEST CLOUD-TOP SURFACE

TEMPERATURE: -331.6F

HIGHEST CLOUD-TOP SURFACETEMPERATURE: -184F

WEATHER OR CLIMATE:

Clouds and storms of fast-moving gases,

high wind speeds

SEASONAL CHANGES:Few, being so far from Sun

Saturn's northern hemisphere ispresently a serene blue, much like

that of Uranus or Neptune.

26

SATURN

Saturn is the only planet whosedensity, or mass per volume,is less than water. If there were

a tank of water big enough tohold it, Saturn would float.

Titan is the second-largest moonin the solar system, behindJupiters Ganymede.

Titan has a thick atmosphere.

Its atmosphere is mainlynitrogen (like Earths), plusmethane, ethane, acetylene,propane, carbon dioxide, carbonmonoxide, hydrogen cyanide,and helium.

After Titan, the second to fifth moons discovered for Saturnwere observed by Giovanni Domenico Cassini.

YEAR MOON DIAMETER DISTANCE

1684 Tethys 659 miles 183,056 miles1684 Dione 696 miles 234,505 miles1672 Rhea 951 miles 327,525 miles1671 Iapetus 892 miles 2,212,081 miles

A selection of shots ofTitan from the EuropeanSouthern Observatory.

Average distance from Sun806 million miles


Closest distance to Sun(perihelion) 838 million miles

Farthest distance from Sun(aphelion) 940 million miles




Time for one orbit(Saturn year) 29.46 Earth years

Axial rotation period(Saturn day) 10.77 Earth hours

See page 10 for information on GALILEOGALILEI.

Known for its glistening, breathtakingly beautiful rings, Saturn is the

solar systems second-largest planet after its neighbor, Jupiter. Saturn

was the Roman god of farming, civilization, prosperity, and also the

name of the rockets that powered the Apollo astronauts to the Moon. Due to its

fast spin, gas giant make-up, and very light weight compared to its size, Saturn

bulges around its equator as it rotates. This means the planet is 7,456 miles

wider than it is tall.



Tilt of axis 26.7





Number of moons 50-plus

RingsThese are made of billions offragments of ice and rock whichreflect sunlight, glisten andsparkle. The largest particles arethe size of a car.

Fainter, more distant rings

Outermost main ring A

Middle ring B

Innermost main ring C

Innermost ring D

Cassini Division

Encke Division

Equatorial ZoneRotates about 25 minutes fasterper Saturn day than the

Temperate Zones, and has widercloud banding.

North Temperate ZoneClouds and winds of 1,118 mph.

South Temperate ZoneLighter colored clouds and a

warm dark spot.

Saturns poles are shown in thisNASA image.

CORE Saturns core is probably very hot, nearly12,000C, and the planet gives out more heat than itreceives from the Sun.

SOUTH POLE A very hot region that glows bright oninfrared photographs.

BAND CLOUDS Less obvious than Jupiters,consisting of stripes and zones of clouds at differenttemperatures. They tend to be wider nearer the equator.

WHITE SPOTS Tend to come and go, probablyareas of swirling gases.

2,500 years aSaturn was then the Rom

1610Galileo sawside of Saturof its rings.

1655Christiaan HTitan and gaSaturns ring

1789William HeSaturn bulgeflattens at th

1847John Herschseven moon

1979Pioneerwasto visit Satu

1980Voyager 1 spictures of t

1981Voyager 2fand discoveincluding dain Saturns Bby Cassini),rings, and m

1997Cassini-Huylaunched on

2004Cassini-Huymoon Phoebreached Sat

2004After two TitHuygens lan

from the CaDecember 2

2005Huygens pluatmospheresending infodown. Cassand fly pastespecially T

2008Expected enforCassini omay be exte

S

TIM

The rings of Saturn were first noticed by Galileo, who could not quitemake them out with his early telescope. He guessed they might beMoons, one on each side, and called them Ears of Saturn.They appear to change in shape when viewed from Earth, as they aretilted and slowly turn with Saturns orbit, so we see them at differentangles. Viewed edge-on, they are at their thinnest, about every15 years. Each main ring is made of thousands of smaller ringlets.

Name Inner edge d is tance Width (mi les)from Saturn (miles)

D Ring 3,726 4,440

C Ring 9,010 10,874

Columbo Gap 11,060 62.14

Maxwell Gap 17,088 167.7

B Ring 19,884 15,835

Cassini Division 35,728 2,920

A Ring 38,649 9,072

Encke Division 45,714 202

F Ring 49,834 314

G Ring 64,584 4,971

E Ring 74,565 186,420

Saturn has been exploredby a number of probes.

A NASA photographof Saturn.




ORBIT DETAILS

Sun

Saturn

OTHER FEATURES

MAIN MOONS

TITAN THE RINGS OF SATURN

VAST BUT LIGHT


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28

Uranus is the third gas giant and seventh planet from the Sun.

It is very similar in size and structure to Neptune, being partly gas,

but also containing much rocky and frozen material. The axis of

Uranus is almost at right angles to the Sun. Some scientists believe an Earth-

sized object crashed into Uranus soon after it was created, giving it its

unique axis. The planet is named after the Greek god of the heavens, who

was also the father of Saturn.

URANUS

Uranuss innermost principal moon,

Miranda, has one of the oddest

appearances in the solar system.

Massive canyons scar the surface, as

well as mountains, cliffs, and craters.

Three huge race-track-like shapes,

calledovoids, are prominent, perhaps

formed by rocks being pushed up

from within.

Mirandas Verona Rupes is a huge

fault scarp. At 12.4 miles high, it is

the highest cliff in the solar system.

There are also many smaller grooves

on Miranda that look like aerial

pictures of strip mines on Earth.

Miranda may have frozen water,

methane-type substances, and rocks

on its surface.

Due to Uranus axis tilt, the planetspins as if lying on its side, rollingaround the Sun. The axis of Uranusdoes not move as it orbits the Sun.

The southern pole of Uranus (pointingsideways) faces the Sun for a short time.Then, as the orbit continues, the northernpole gradually comes around to face theSun, in the opposite part of the orbit.

MOON DIAMETER DISTANCE

Miranda 293 miles 80,703 miles

Ariel 719 miles 118,631 miles

Umbriel 727 miles 165,292 miles

Titania 980 miles 271,117 miles

Oberon 964 miles 362,599 miles

There are about 14 smaller m oons inside Mirandas orbit. The largest of those

is Puck, whose diameter is 99 miles across.

ATMOSPHERE:

Mostly hydrogen, about one-sixthhelium, also methane, and traces ofammoni

NATURE OF SURFACE:

Gassy, with any solid surface deep below;glows in sunlight as bright blue-greenor cyan

AVERAGE CLOUD-TOP

SURFACE TEMP: -337F

LOWEST CLOUD-TOP

SURFACE TEMP: -353.2F

HIGHEST CLOUD-TOP

SURFACE TEMP: -328F

WEATHER OR CLIMATE:

Swirling clouds, winds, and gases,despite smooth, glassy appearance

SEASONAL CHANGES:

Extreme, since Uranus lies on its side sothat during each orbit, both poles andthe equatorial regions face the Sun.

Diameter at Equator 31,763.25 miles


Tilt of axis 97.8 (almost at a

right angle to the Sun)





Number of moons approaching30 and counting

Inner Structure

Uranus is probably quite similarin composition all the waythrough, with gases and particlesof rocks and ice intermingled.

ColorUranus usually appears pale tomid blue-green, a color known ascyan, probably because methanecrystals in its atmosphere absorbmost of the red light in sunlight,leaving it mostly blue.

StreakingHubble Space telescope imagesreveal faint streaks thatslowly change, perhaps dueto seasonal variations.

Warmer EquatorDespite Uranuss extreme tilt, theequator is slightly warmer thanthe polar regions.

Uranus has been mapped fromEarth and the Voyagerprobe.

An artists impression of therings of Uranus.

Ancient timUranus may ancient peop

1690John Flamstea dim star-lik

1748James Bradla faint star. Hand 1753.

1764Pierre CharleUranus a doyear to 177

1781William HerUranus.

1787William HerTitaniaand O

1851William Lassand Umbrielthird-nearest October 24.

1948Gerard KuipUranuss innFebruary 16

1977Voyager 2wjourney acro

1977In March, a suspected asa faint star bmanner.

1982Voyager 2ptime when itdirectly towa

1986Voyager 2mon January 2its surface. It and discove10 more mofive visible fro

2007The Sun will equator of Ubetween its abeing directoverhead at

U

TIM

SURFACE FEATURESThere are few obvious featureswhen Uranus is viewed throughtelescopes from Earth. thesurface appears to be smoothwith a satin glow.

MAGNETIC FIELDThis invisible fields center is notin the center of the planet. It istilted at 60 compared to theplanets spinning axis.

Ring Distance from Width of ringcenter of Uranus (miles) (miles)

1986U2R 23,612 1,5536 25,998 0.621.86

5 26,240 1.241.86

4 26,458 1.241.86

Alpha 27,788 2.46.2

Beta 28,378 4.357.46

Eta 29,323 01.24

Gamma 29,596 0.622.49

Delta 30,006 1.865.59

Lamda 31,081 0.621.24

Epsilon 31,777 12.4362.14

A composite image ofUranuss moon

Miranda.

See pages 1819 for information on Earth.

A NASA photographof Uranus.

This image is rendered from

the clouds of Uranus, with theVoyagerspacecraft seen

in the sky above.

Average distance from Sun1,783 million miles


Closest distance to Sun(perihelion) 1,699 million miles

Farthest distance from Sun(aphelion) 1,868 million miles




Time for one orbit(Uranus year) 84.1 Earth years

Axial rotation period(Uranus day) 17.24 Earth hours

ORBIT DETAILS




Uranus

Sun

OTHER FEATURESMAIN MOONS

ON ITS SIDE

RINGS OF URANUS

ODD LITTLE WORLD


17/36

These are very faint, difficult to measure and also seem to change rapidly.

30

Neptunes deep blue color of the fourth gas

justthefactssolarsystem-viny.pdf

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