GCSE Science Review Volume 16Number 4April 2006

ExploringVenus

1 Life in the balance?Philip Seaton

4 Improve your gradeRevision

6 Cooler times ahead?Kim Marshall-Brown

8 Venus ExpressDavid Sang

11 Minerals and rock structureGarrett Nagle

14 Physics connectionsCharles Tracy

17 Try thisPredator and prey

18 Your futureEducational psychology

20 A life in scienceOceanographers

22 Logging data from the world’s oceans

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Contents

Volume 16 Number 4 April 2006

Advisory panelEric AlboneClifton Scientific Trust

Tessa CarrickFounder Editor, CATALYST

David ChaundyFounder Editor, CATALYST

Peter FinegoldThe Wellcome Trust

Peter JonesScience Features, BBC

Sarah LeonardScience Museum

Ted ListerRoyal Society of ChemistryFounder Editor, CATALYST

Ken MannionSheffield HallamUniversity

Andrew MorrisonParticle Physics and Astronomy ResearchCouncil

Jill NelsonBritish Association

Silvia NewtonCheshunt School andAssociation for ScienceEducation

Toru OkanoThe Rikkyo School inEngland

John RhymerBishop’s Wood Environmental Education Centre

Nigel ThomasScience EnhancementProgramme

Charlotte WretonBiotechnology andBiological SciencesResearch Council

Editorial teamNigel CollinsKing Charles I School, Kidderminster

David MooreSt Edward’s School, Oxford

David SangAuthor and editor

Jane TaylorSutton Coldfield Grammar School for Girls

The front cover shows a false-colour radar map of thewest hemisphere of Venus(NASA/SPL).

The end is nigh?It’s April, and the end of the school year is in sight. That

probably means tests and exams, so we have included somesuggestions on how to revise on pages 4–5.

At the end of the nineteenth century, many physicistsbelieved that the end of scientific discovery was nigh — themysteries of mechanics, electromagnetism and thermo-dynamics had been sorted out, and only a little tidying upremained. Then, in 1905, along came Albert Einstein with histhree dramatic theories. On pages 14–16, you can read abouthow twentieth-century physics turned conventional ideas ontheir head.

In fact, there’s always something new around the corner —that’s what makes science exciting. Take the photo on the frontcover. It’s a radar map of Venus, a planet about which we willlearn a lot more soon, thanks to Venus Express (see pages8–10).

David Sang

T he main reasons for this crisis are welldocumented. The world’s tropical forests aredisappearing at an alarming rate, both due

to logging for the timber trade (much of it illegal) andto land conversion to agriculture. Vast tracts oflowland forest have been converted to banana, oilpalm or pineapple plantations. Large areas of theAmazon Basin are currently being converted to soyacultivation or pasture for cattle ranching.

What is not always appreciated is that many of the world’s temperate forests face a similar threat.Increased logging is taking place in the far east of Rus-sia, for example, and clear felling is continuing alongstretches of the northwestern coast of North America.

The potentially harmful effects of global warmingare of increasing concern. As average temperaturesrise, habitats may change and become unsuitable fortheir resident plants and animals. To survive, manyneed to migrate to more suitable areas, but habitatfragmentation means that such species may literallyhave nowhere else to go.

The island of Mauritius is a tropical paradise. Mostvisitors do not realise that only around 1% of itsoriginal forest remains. The lush green forest canopyis largely made up of introduced exotic species —guava and privet. Invasion by exotic species is anincreasing menace to natural populations. Of course,Mauritius was once home to the dodo, tragicallyextinct within less than 100 years of its discovery in 1598.

Sadly, examples of illegal and unsustainable huntingof animals for local trade and consumption, as well as for the international market, are easy to find. InChina there is an illegal market in snow leopard skinsand bones. The bones are used in traditional medicines,as are the gall bladders of bears. In parts of Africa where there is a shortage of protein, there is a thrivingbush meat trade, including such wild animals as chimpanzees.

Habitatfragmentation: afterclearing the naturalvegetation in an area,small fragments of the originallandscape aresometimes allowed toremain. Unfortunately,the number of speciesable to survive in suchsmall parcels of landdeclines rapidly.

Plant migration: unlikeanimals, plants have toremain rooted to thespot. Plant populationscan, however, migrateover time through seeddispersal.

1April 2006

Philip Seaton

GCSE key wordsHuman impact onthe environment

DeforestationGlobal warming

Life in the balance?Much of our planet’s biodiversity appears to be teetering on the brink of a man-madeextinction crisis. Scientists have suggested that, unless urgent action is taken now, manyspecies will disappear in the next 50 years.This article looks at some of the issuesinvolved.

Gre

gory

Dim

ijian

/SPL

Madagascar

Mauritius

l To learn more aboutOrchid ConservationInternational go to its website (www.orchidconservation.org).

2 Catalyst

Box 1 Case study: a Kew expedition to MadagascarDuring our 11-hour drive to the RanamofanaNational Preserve it was easy to believe that only10% of Madagascar’s natural forest remains. Formost of the journey the countryside was a mosaicof rice paddies encircled by bare hillsides with theircharacteristic red soils which, from the air, can beseen bleeding into the surrounding Indian Ocean.

The lush humid forest of Ranamofana boasts atotal of 20 lemur species, each living in a slightlydifferent ecological niche. The highlight was finding the rare golden bamboo lemur. Only 100 individuals remain in the wild, 20 of which are currently protected, at Ranamofana.

In contrast, the Itremo Plateau was hot and dry.We were looking for plants of an endangeredorchid, Angraecum longicalcar, which grows in fullsun on marble outcrops. We soon discovered thatthe total population had declined to no more than 25 plants. The local herdsmen routinely burn thegrassland, to stimulate the formation of fresh greenshoots for their herds of zebu cattle. Alarmingly,part of the population of orchids had recently beenaccidentally burned. In addition, some of theremaining plants had been removed by collectors,and one of the outcrops was being mined for itsmarble. Truly, this is an orchid species on the edge.

Figure 1 Mauritiusand Madagascar areislands in the IndianOcean

Phil’s colleague David Roberts from Kew locatingthe Angraecum longicalcar in Madagascar

Angraecum longicalcar

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Why should we care?There are various reasons why we should beconcerned. The first is an economic argument. Illegallogging threatens the livelihoods of many localcommunities that depend on forest resources foremployment and income. Trees bind the soil togetherand, particularly on steep slopes, prevent it beingwashed away by rainfall.

Plants and animals are important sources of food,fibres and, potentially, undiscovered medicines.

At the heart of the matter is the fact that we dependon other species for our continued existence on thisplanet. They are part of the fabric of life, and foodchains and food webs may begin to unravel as keyorganisms are removed.

Ultimately, after millions of years of evolution andcoexistence, many people would argue that it ismorally wrong to cause the extinction of plants andanimals.

What is being done?All of the above can make pretty depressing reading,but fortunately there appear to be an increasingnumber of people who care enough to be doingsomething, and more and more people are willing topay to see wildlife in its natural habitat. The CentralAmerican country of Costa Rica, for example, derivesmore income from ecotourism than any other source.Here are just a few examples of the sorts of conser-vation activities and projects that are taking placearound the world.

Mauritius kestrelIn situ conservation involves conservation of plantsand animals in their natural habitats. The Mauritiuskestrel declined to just four wild individuals, butcaptive breeding and subsequent reintroduction hassaved this beautiful bird from extinction.

African elephantsOne of the successes of the conservation communityhas been the international agreement banning tradein ivory and its products, thereby halting the lucrativemarket for poached tusks, and the catastrophicdecline in African elephant populations.

Lady’s slipper orchidIt is not only plants and animals in exotic places thatare at risk. In Britain our native lady’s slipper orchiddeclined to one individual plant remaining in a secretlocation somewhere in Yorkshire, after the plants hadbeen dug up by collectors. Artificial pollinations werecarried out by staff at the Royal Botanic Gardens,Kew, the seeds germinated in the micropropagationunit, and a healthy population of seedlings was onceagain established in its natural habitat.

Sustainable developmentEx situ conservation is conservation of materialoutside its natural habitat.

The key phrase in the vocabulary of today’s conser-vationists is sustainable development. In Mexicomany orchid species are used in religious festivals todecorate the altars. Not only are the flowers removedfrom the wild, but also sections of the plants, as thismeans that the flowers will remain fresh for a longertime. This leads to a decline in natural populations.

Projects are now being set up to store seed of theseorchids for the future in germ banks, and laboratoriesare being established to raise orchids from seed for subsequent cultivation by the local people. TheMillennium Seed Bank Project at Kew aims toconserve seeds representing 10% of the world’s flora by 2010, concentrating particularly on semi-arid areas, where most people live on land on which agriculture is marginal.

Philip Seaton taught biology for more than 30 years. He now works full time in orchid conservation. He is secretary to the Orchid Specialist Group of the IUCN/SSC, the WorldConservation Union, and Orchid Conservation International, aRegistered Charity.

The natural vegetationof much of Britain iswoodland, but mostforests were cleared foragriculture thousandsof years ago.

l The beautiful blueBrazilian parrot, Spix’smacaw, was declaredextinct in the wild inDecember 2000. Incontrast, after anabsence of more than60 years, the ivory-billed woodpecker hasrecently been sighted inthe ancient cypressswamps of Arkansas,USA. To learn moreabout both birds go towww.arkive.org/species

l To find out moreabout the MillenniumSeed Bank Project visitthe Kew website onwww.kew.org.uk andclick on WakehurstPlace.

3April 2006

Box 2 Case study: cloud forests ofCosta RicaCloud forests are among the richest habitats onEarth. Constantly bathed in rain and mist, thebranches of the trees are draped in a dense carpetof orchids, bromeliads and ferns. As globaltemperatures rise so the cloud base moves up themountain sides, and those plants and animalsmigrate up the mountains along with the changingconditions. Those that required the specialconditions at the tops of the mountains havenowhere left to go.

A lady’s slipper orchid

Mal

kolm

War

ring

ton/

SPL

It’s that time of year again — exams. This Improve your Grade gives you importantadvice on when and how to revise.

It’s hard to get started revising because there isalways something more urgent to do. Begin bymaking a revision timetable which covers the areas

you need to revise. This will make you realise thatthere is a lot to do and that you need to start as soonas possible.

Don’t leave learning topics until just before theexams. It makes your life difficult. Learn topics youcovered early in your course well in advance and usethe weeks before the exams for learning your mostrecent work and revision.

What should I revise?You need a list of the topics in your GCSE specifi-cation. If your teacher hasn’t given you one, check thecorrect title for your exam and go to your exam boardwebsite (Box 1). Download a copy of the specif i-cation. Now you are ready to get started.

It makes you feel good if you revise topics you likeand got high marks for — when you test yourself youknow it. Unfortunately, these areas aren’t the onesyou need to work on. You must identify your weakspots and start with them.

Use your target sheets and checklists (Figure 2) tohelp you prioritise revision topics. Look at the testsand assessments you have done during the year. Tickoff the topics that you gained good marks for (goodmeans all or most of the marks for the questions).You should be left with a list of areas you didn’t do sowell on — these are your first priority.

Break each topic down into bite-sized chunks thatare easier to remember and focus on. For example, abiology module on control and coordination can bebroken down into nerve cells, synapses, reflex arc,hormones, glands and plant hormones.

If you haven’t got target sheets or tests, lookthrough your books and files. Make a list of the areasyou didn’t do very well in and start with these.

Getting down to itLook at your notes. Is there any unfinished work? Are there any gaps from when you were ill or playingfor a team? You need to f ill these gaps in yourknowledge before you start to revise.

Use a range of sources for each topic. Begin withyour notes and your textbook if you have one. Readmore from a different book in the school library, aCD-ROM or a useful website such as www.s-cool.co.uk,and your back issues of CATALYST. The sources willoverlap, but each presents the material in a differentway — one of them will be right for you.

4 Catalyst

Friends can be usefulrevision aids. When youwork together youargue about topics. Thismakes you formulateyour ideas and turn yourthoughts into speech —which helps youremember them.

The internet is afantastic source ofinformation, but youcan waste a lot of timewith useless sites sochoose the key wordsfor your searchcarefully.

RevisionImproveyour grade

Checklist — heart

Can label a heart diagram

Can use arrows to show flow

Can explain the job of valves

Can explain why pulse varies

List 3 differences betweenarteries and veins

Explain why capillaries havethin walls

Figure 2 Revision checklist

Control and coordination

Nervous system

Animal hormones

Plant hormones

Response to light direction

Auxin

Rooting powder Fruit

ripening

Synapse

InsulinAdrenalin

Control of blood sugar

‘Fight or flight’

Control of fertility

Reflexes

Effect of drugs

Other hormones

Oestrogen and progesterone

Central nervous system

Structure of neurone

Figure 1 Spiderdiagram for controland coordination

Box 1 Examination board websitesAQA: www.aqa.org.ukOCR: www.ocr.org.ukEdexcel: www.edexcel.org.ukNorthern Ireland: www.ccea.org.ukScottish: www.sqa.org.ukWelsh: www.wjec.co.uk

What’s the best way to revise?Different people learn best in different ways. Try a fewtechniques to find which suits you best. The worstway is just to sit and read your notes or a textbook —this won’t help you to remember much. You need tobe more active and make notes or draw diagrams, forexample.

Revision notesThese are very useful. Many people write down keywords and points as they read. No one else is going toread your notes so it’s okay to scribble and use abbre-viations. The best notes are:• short• limited to key points• full of cues to help you recall the data

DiagramsThese are good if you find it easier to take in visualinformation. You can construct spider diagrams(Figure 1) and flow charts. Venn diagrams can beuseful too. Try looking at the animations on a CD-ROM and drawing your own diagrams on a note pad.

The drawing and writing isn’t important, it’s theprocessing of information that you do while makingthe diagram or chart which makes you remember theinformation. Try turning a spider diagram into aconcept map (Figure 3) by writing on the linksbetween words — this will make you think about therelationships between topics.

TablesMaking tables can help you learn too. Look at Table 1about the electromagnetic spectrum. The table hasmemory cues: there are seven sections to remember,put in order from highest frequency to lowest.

Make a mnemonic of the initials GXUVIMR to helpyou remember it. For example: Giant XylophonesUpstage Very Important Musical Russians.

FinallyDon’t forget to revise your practical activities: thereasons why you used particular materials andequipment, how you made your work a ‘fair test’ andhow you explained the results scientifically.

You will also have done work on the development ofscientific ideas in history; you might have to explainsome of these in an exam too.

Jane Taylor teaches biology and is an editor of CATALYST.

Philip Allan Updatespublishes FlashReviseCards and TopicCueCards for GCSEScience. See the insert inthe centre of this issuefor more details.

It is never too early to start revising.

5April 2006

Control and coordination

Homeostasis

Action

Diabetes

InsulinKidney

Kidney tubule

ADH

UrineGlycogen

Adrenalin and glucagon

Endocrine glands

Adrenal gland

Anabolic steroids

Pancreas

Ovary

Testis

Blood sugar

Water content of blood

Animal hormones

Chemicals used to coordinate body activity

Regulates body processes

Slow,�long

lasting

Made by

Done in

AtLess

Stored in �liver as

Makes adrenalin

Abused by athletes

Makes insulin

Makes testosterone

Makes oestrogen and progesterone

Water reabsorbed into body

Except

Regulated within limits

Fail to regulate

Brings down level

Releases sugar from

storage

Glucose converted to

Promotes release

Regulated within limits

Adrenalin

indicates further links could be made

Figure 3 Part of aconcept map of controland coordination

Table 1 Electromagnetic spectrum revision table

Type of wave Frequency Uses1 Gamma rays Highest Treating cancer2 X-rays Examining broken bones3 Ultraviolet Sterilising labs4 Visible Photography5 Infrared Heating6 Microwaves Communications7 Radio waves Lowest Broadcasting

25° N section

Gulf stream

GSR

Scandinavian array

Subtropical recirculation

Deep southerly return flow

Winter sea-ice cover

Key Sinking regions

Figure 1 Oceancurrents

T hree scientists at the National OceanographyCentre (NOC) in Southampton — HarryBryden, Hannah Longworth and Stuart

Cunningham — published the above f indings lastDecember in the science journal Nature.

What is overturning circulation?Warm water heated in the tropics heads northwardsas the Gulf Stream. At latitude 45°N (level with Spain)it splits in two. One branch heads south back to the equator due to the Trade Winds and the Earth’s

rotation. This is what happens in the Pacific Oceanand it is called a circulating current. The other branchcontinues northwards past Britain and Norway andfar north into the Arctic Ocean. Westerly winds passover this warm water, pick up the heat and blow it overnorthwest Europe, which keeps our climate moderate.

When this water reaches the Arctic, it gets very cold.As ice forms (which is fresh water) the salt is left behindand this salty brine water becomes very dense, whichcauses it to sink. It sinks to the ocean floor and makesthe return journey south, very cold and salty. As thewater sinks it effectively pulls water from the south toflow northwards. This is called overturning circulation.

In the absence of overturning circulation in the northern Pacific Ocean, Alaska, which is on asimilar latitude to the UK, is much colder in thewinter than here.

The important newsIt would seem that more of the Gulf Stream is goinginto the southward circulating branch, less is makingits way north past our shores and less is returning tothe tropics as deep, cold, salty water. This could bedue to global warming creating fresher waters in thenorth through more rain and melting glaciers — a bitlike the scenario in the film The Day After Tomorrowbut nowhere near as fast!

How do scientists know this?Scientists have been measuring the ocean as it flowsacross latitude 25°N which runs just below theCanary Islands, stretching from Miami to the Saharancoast of Africa. There have been five research cruisesover the last 50 years, in 1957, 1981, 1992, 1998 andthe last one in 2004. Until 1992 the figures recorded

6 Catalyst

Kim Marshall-Brown Cooler times ahead?

Scientists have found that the overturning circulation in the Atlantic Ocean, which maintainsEurope’s moderate climate, was weaker in 2004 by 30% relative to earlier estimates. Whatdoes this mean and what impact could it have on our climate?

Nat

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Right: This image of people skating onthe frozen Thamesrepresents a potential,if highly unlikely,future scenario

were pretty much the same. On this last cruise thefigures showed that the flow had weakened by 30%.

This may be seasonal or just a blip; withoutconstant measurements we cannot know for certain.Scientists decided to monitor the circulation and heattransport more closely by taking more frequent meas-urements of the temperature and salinity of the waterand the speed at which it is moving.

Since 2004 scientists at the National OceanographyCentre, Southampton, led by Dr Stuart Cunningham,have deployed an array of instruments across theAtlantic Ocean at 25°N. The instruments measurecurrent speeds, temperature and salinity continuouslyand record them on dataloggers. The instruments aretethered at different depths to a mooring thatstretches from just under the water surface to theseafloor, involving around 5 km of cable in some areasof the ocean. Nine are sited across the Deep WesternBoundary Current east of the Bahama Islands, fouracross the Mid-Atlantic Ridge and nine across thecontinental slope off the coast of Africa. The backpage shows one of the moorings in more detail andexplains how it works.

Scientists sailing on research vessels retrieve thedata from the buoys once a year. The monitoringarray involves close collaboration with American

7April 2006

l Find out more aboutthe three scientistsinvolved in the project in A Life in Science onpages 20–21.

The work of scientists at the NationalOceanography Centre isdescribed on its website(www.noc.soton.ac.uk).

Nat

iona

lOce

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on

Clockwise from top left:

A mooring cable beingplayed out

Redundant railwaywheels set as anchorsfor the mooring on thesea bed

Glass floats in theirprotective covers (seethe back page)

scientists at the University of Miami and NationalOceanic and Atmospheric Administration’s AtlanticOceanographic and Meteorological Laboratory. Theproject is due to end in 2008, giving 4 years ofcontinuous observation.

Climate predictionsScientists can use computer models to investigatedifferent climate conditions in the future (seeCATALYST Vol. 15, No. 4). When they have run themodel with the overturning circulation slowed down,the UK climate, particularly Scotland, gets muchcolder, by several degrees. This can be quite dramaticand the models suggest it could happen in a fewdecades rather than hundreds of years. The over-turning circulation has turned off before, during theice ages. We know this from looking at samples ofsediment taken from the seafloor — the paleo-oceanrecord and ice cores.

Look out for reports from scientists atSouthampton, as they collect and analyse the datacoming in over the next 3 years!

Kim Marshall-Brown is the editor of Ocean Zone, aquarterly newsletter published by the National OceanographyCentre, Southampton.

T he Venus Express spacecraft was launched at3.30 in the morning on 9 November last year.The mission is modelled on ESA’s successful

Mars Express mission (see CATALYST Vol. 14, No. 2).The term ‘Express’ refers to the speed with which themission has been carried out, from first approval in2002 to launch in 2005.

Journey into spaceThe trip to Venus lasts 153 days. For most of this time,the strongest force on the craft is the pull of the Sun’sgravity. Once Venus Express is captured by Venus’sown gravitational pull, the engineers at the controlcentre in Darmstadt, Germany, need 5 days tomanoeuvre it into its operational orbit.

There is no lander on this craft; it is planned tofollow an extended elliptical path around the planet(Figure 1). This takes it first within 250 km of theplanet’s surface, and then far out, 66 000 km intospace, before it plunges back inwards once more. Thisis a polar orbit, giving the craft a view of the planet’sentire surface as it rotates slowly below.

Venus is closer than Earth to the Sun, so the Sun’srays are twice as intense. This has important conse-quences:• There is an abundant supply of energy for thespacecraft’s solar panels, which generate its power.• At the same time, there is a serious danger that thespacecraft could overheat, so it has built-in systems toremove excess heat and radiate it back out into space.

The spacecraft is something of a flying computer,with on-board systems which store data and processit, ready for transmission back to Earth.

8 Catalyst

David Sang

GCSE key wordsForcesOrbit

Tectonic platesGreenhouse effect

Table 1 Venus and Earth compared

Venus EarthMass (kg) 4.87 × 1024 5.98 × 1024

Equatorial radius (km) 6052 6378Average distance from Sun (km) 108 000 000 150 000 000Year length (Earth days) 225 365Rotation period (Earth days) 243 1Mean surface temperature (°C) 465 15Tilt of axis 178° 23.5°Surface gravity (N/kg) 8.9 9.8

The European Space Agency (ESA) isoff on its travels once more — this timeto Venus. What is to be gained from avisit to our cloudy neighbour, a planetwhich some astronomers describe as‘Earth’s evil twin’?

ESA

/Sta

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-SC

orva

ja

The Soyuz-Fregat rocketcarrying Venus Express liftsoff on 9 November 2005

Why visit Venus?In many ways, Venus is comparable to Earth (seeTable 1). It is a rocky planet, with similar size, massand gravity. However, there are two major differences:Venus is much hotter than Earth and its atmosphere is very different from ours. These two facts areconnected, and they explain why Venus is of interestto us earthlings.

The atmosphere of Venus is dense (its pressure isabout 90 atmospheres), and it is largely composed of carbon dioxide. This causes it to have a stronggreenhouse effect; infrared radiation is trapped inthe atmosphere, so that the surface temperature can rise as high as 500°C. This gives Venus some very odd weather, with winds up to 250 km/h, luridyellow clouds of sulphur and heavy falls of leadsulphide ‘snow’.

Venus Express will orbit high above this murkyworld, using radar to detect the planet’s surfacethrough the dense cloud layer.

Understanding how Venus’s atmosphere works mayhelp scientists to predict how Earth will change as we

pump increasing quantities of greenhouse gases intoour own atmosphere. It may also give us ideas aboutthe Earth’s distant future. Dr Andrew Coates fromUCL’s Mullard Space Science Laboratory, who is oneof the UK scientists involved in the mission, says:

This is a wonderful mission of discovery — not only tofind out why Earth’s twin went wrong and to study its strange atmosphere now, but also to glimpse apossible future for the Earth. The extreme example ofVenus will test models of our own atmosphere andhumankind’s contribution to greenhouse gases here. It

As well as Venus Expressand Mars Express, ESAhas the BepiColombomission to Mercury, so itwill have visited each ofthe rocky planets in theinner solar system. Thefinal bill for the missionwill be about 200 millioneuros — similar to thecost of making ablockbuster movie.

9April 2006

Figure 1 As Venus Express orbits, the planet willrotate slowly beneath it, allowing all parts of thesurface to be scanned. During the limb-soundingexperiment, instruments gather starlight which haspassed through the planet’s atmosphere and analyseit to learn more about its physical and chemicalproperties

Nadir pointing

Limb sounding

Apocentre observation

ESA

ESA

/S.C

orva

ja

Artists’s impressionof Venus Expressorbiting Venus

Venus Expressbeing packed readyfor shipping to itslaunch site

will also give a preview of what it may be like in 2 billionyears’ time when the Sun has got brighter in itsevolution along the main sequence of stars. At thattime Earth will no longer be in the ‘Goldilocks’ zoneand our planet may become more like what Venus islike now.

Planetary pressure cookerVenus, like Earth, is rocky, and shows signs of volcanicactivity. Its surface is cratered like the Moon, but thereis a difference — the oldest craters on Venus are no

older than 500 million years, despite the fact that the planet is over 4000 million years old. It seemslikely that the planet’s entire surface was renewed 500 million years ago.

Earth has tectonic plates which move around andvolcanoes which explode. These release any build-upof pressure beneath the crust. Venus seems to bedifferent; its surface may be a single plate. As pressurebuilds up inside, a sudden outburst turns the wholething over, creating a completely resurfaced planet.

Instruments on boardThe main structure of Venus Express was built by theAstrium company at Stevenage in Hertfordshire. Itcarries a number of instruments for studying theplanet (Figure 2):• MAG looks at the planet’s magnetic field whichdoes not come from inside the planet, but from itsinteraction with charged particles in the solar wind.• VIRTIS uses ultraviolet, visible and infraredradiations to look at the planet’s cloudy loweratmosphere.• PFS measures temperatures and determinescomposition within the atmosphere.• SPICAV/SOIR looks at the upper atmosphere.• VMC is a camera that photographs clouds and theplanet’s surface.• VeRa uses radio waves to study the ionosphere, an ionised layer high in the atmosphere.• ASPERA looks at interactions between the solarwind and Venus’s atmosphere, by collecting atomsand molecules leaving the planet.

To ensure that the craft is always pointing in theright direction, it has four pairs of thruster rockets,each of which provides a force of 10 N. It uses startrackers to check its orientation in space, and thenfires the thrusters for just the time necessary to put itinto the correct orientation.

Venus viewed from EarthVenus may be familiar to you as the ‘evening star’; itappears as a bright, untwinkling speck of light in thewestern sky at dusk. At other times, it appears arounddawn in the eastern sky, and is known as the ‘morningstar’. Seen through a telescope, it shows phases, justlike the Moon. Its apparent size also changes, fromsmall when it is full to large when it is just a slimcrescent.

This can be explained by picturing Venus in its orbitaround the Sun (Figure 3). When it is on the oppositeside of the Sun to Earth, it looks smaller, but we cansee the whole of its illuminated side. When its orbitbrings it close to Earth, we see the unilluminated sideof the planet. Four hundred years ago, these observa-tions helped to convince Galileo that Venus orbitedthe Sun, rather than Earth.

David Sang writes textbooks and is an editor of CATALYST.

10 Catalyst

Sun

Venus

Earth

2

16

5

4

6 5 4 3 2 1

3

Figure 3 The phasesof Venus

Figure 2 Instruments on board Venus Express

MAGVIRTIS

PFS

SPICAV/SOIR

VMC

VeRa

ASPERA

ESA

l Follow Venus Expresson the ESA website(www.esa.int/venus).

l Explain why Venus isalways observed atdawn or dusk, close tothe Sun in the sky.

Of the 3700 minerals discovered so far, mostare rare, sometimes merely a thin coating ona rock. Others, such as quartz, feldspars and

calcite, are found worldwide. Some exist only asmicroscopic crystals; other crystals may weigh severaltonnes.

Minerals are formed in a wide variety of environ-ments. For example:• opal forms from water percolating down near-surface joints between rocks• gypsum forms from warm saline waters• garnet forms at a temperature of 500°C in solidrocks 25 km below the surface• olivine forms from magma at 1100°C, either on thesurface or deep below the crust• galena forms in veins from hydrothermal waters atdepth

How do minerals form?The whole Earth, apart from the liquid outer core andisolated patches of magma elsewhere, is made ofminerals. The chemical constituents of the Earth arecontinually being reworked; virtually nothing new isbeing made.

Eight elements — oxygen, silicon, aluminium, iron,calcium, sodium, potassium and magnesium — makeup 98% of the Earth’s crust by weight. Oxygen is 47%of the crust by weight and 93% by volume. Some 20 or

so mineral families make up 99% of the crust’s mass.Whether a particular mineral grows or not dependson the appropriate elements being present in the rightconcentration under the right conditions (mainlytemperature and pressure).

Chemical compositionA few minerals contain only one element, such as gold(Au) and diamond (C), but most are compounds,such as galena which is formed of lead (Pb) andsulphur (S). Figure 1 shows the most frequently foundelements in the Earth’s crust. It follows that mineralswhich contain mixes of these elements are common,whereas minerals formed of rare elements, such asdiamond which is made from carbon, are rare. Thus,rocks containing silicon are common, while non-silicon containing rocks are much less common.

Garrett Nagle

GCSE key wordsRocks

SilicatesMineralsDiamondGraphite

Minerals and rock structure

The oldest knownmineral is zircon: 4300 million-year-oldcrystals of zircon werefound in a sedimentaryrock in Australia whichderived from an earlierigneous rock.

Hydrothermal: minerals dissolved insuperheated waterunder pressure.

Sedimentary: rocksmade by the depositionof material under waterwhich havesubsequently beencemented together.

11April 2006

The rock cycle is responsible for the formation of many different types of rocks and minerals.This article looks at the formation of minerals, their composition and their internal structure.

Figure 1 Composition of the Earth’s crust (mass)

Oxygen (46.6%)

Silicon (27.7%)

Aluminium (8%)

Iron (5%)

Others (12.7%)

Cor

el

Physical propertiesThe physical properties of minerals depend on theirchemical composition and structure. For example,graphite and diamond have the same compositionbut quite different structures and totally differentproperties. These properties reflect the conditionsunder which the diamond and graphite were formed.Diamond, which is formed under high pressure, ishard, whereas graphite, which is formed under lowpressure, is soft.

Most rock forming minerals are silicates that can bebonded as isolated tetrahedras (olivines), chains(pyroxenes), double chains (amphiboles), sheets(micas) or frameworks (quartz) (see Figure 2).

Bonds in the crystalsAtoms in mineral crystals are held together by electrostatic bonding forces, which in about 90% of minerals are ionic or predominantly so. An ion is an atom that has become charged, either by the lossof an electron to become positively charged, or bygaining an electron to become negative.

Mineral hardnessThe hardness of a mineral is usually measured onMohs’ scale of hardness (Table 1). Diamond is thehardest mineral, with a value of 10 on the scale, whiletalc, the softest mineral, has a value of 1.

A harder mineral can scratch a softer one but notthe other way round. Hardness depends on theatomic structure of the mineral, and how densely theions are packed within the structure. Diamond is farmore tightly packed than graphite, although they havethe same chemical composition (Figure 3). Similarly,within silicate rocks, micas have a hardness of 2 to 3due to the atoms being loosely packed. In contrast,olivines with a hardness of 6.5 and quartz, hardness 7,are densely packed.

12 Catalyst

Figure 3 Structure of (a) diamond and (b) graphite

Mineral types withexamples of formula Structural type and silicate unit

Olivines: e.g. Mg2SiO4 Single tetrahedra (SiO4)4−

Garnets: e.g. MgAl2(SiO4)3

(a) Relative scale (b) Schematically

Pyroxenes: e.g. Mg2Si2O6 Single chains (Si2O6)

4−

Plan viewof chain

End-on view

Amphiboles: Double chains (Si4O11 (OH))7−

e.g. Ca2Mg5(Si8O22)(OH)2

Plan viewof doublechains

End-on view

Micas: Sheet silicates (Si4O10)4−

e.g. KMg3(AlSi3O10)(OH)2(also clay minerals)

Quartz: SiO2 Framework silicates (SiO2)Feldspar: e.g. NaAlSi3O8

Figure 2 Silicates

(a) Diamond

(b) Graphite

CleavageCleavage is the way in which a mineral breaks along adistinct, well-defined plane of weakness. These lines ofweakness are related to the internal atomic structure— in effect, they are lines of weakness in the chemicalbonds between chains and layers of atoms. Micashave well-developed cleavage direction, and themineral splits in thin sheets. The bonds between thesheets are weaker than the bonds within the sheets.

Crystal formCrystal form refers to the shape of the crystals. Thisdepends on the atomic structure of the elementsinvolved (Figure 4). When there are many elements ina mineral, crystals may interfere with the growth ofother crystals, so crystal structure is not always asstraightforward as the theory suggests.

Colour and streakColour is one of the more obvious properties of amineral although it can be affected by the impuritiesof a handful of atoms. Quartz (SiO2) occurs in arange of colours including colourless (rock crystal),white, pink (rose quartz), black (smoky quartz) andpurple (amethyst). Hardness and cleavage are notaffected by colour. Gemstones such as ruby (red) andsapphire (blue) are variations of corundum (Al2O3).Streak is the colour of the mineral when powdered.

Relative densityThe relative density of a mineral is the ratio betweenits mass and that of an equal volume of water.Relative density depends on the atomic mass of theelements and how closely packed the atoms are.Diamond and graphite are both composed of carbon,but diamond has a high relative density (3.52)compared to graphite (2.3). Most minerals have arelative density of between 2.5 and 3.5, with theexception of minerals containing heavy metals such asbarium (barite, barium sulphate BaSO4, with arelative density of 4.5). Gold has a relative density ofup to 19.3.

Garrett Nagle teaches geography at St Edward’s School inOxford and is an author of many geography textbooks.

Graphite is soft becausethe layers of carbonatoms can slide overeach other easily.

Diamond is hard sinceeach carbon atom isstrongly held to fourothers in a rigid three-dimensional network.

Positive ions are calledcations. Negative ionsare called anions.

l Go to www.minersoc.org/pages/links/schools.html and follow the links to other usefulmineralogy and geologywebsites.

13April 2006

Fayalite Fe2SiO4

Forsterite Mg2SiO4

Olivine (Mg, Fe)2 (SiO4)

Gypsum CaSO4

.2H4O(Hydrated calcium sulphate)

Pyrite FeS2 (Iron sulphide)

Quartz SiO2 (Silicon dioxide)

Figure 4 Crystal forms of some common minerals

Box 1 SilicatesAbout one third of all known minerals are silicates. They are the most impor-tant rock forming minerals. Many of them are rare but there are a few types —olivines, pyroxenes, amphiboles, micas, clay minerals, quartz and garnet —which are quite common, and these make up 95% of the Earth’s crust.

Types of silicate mineralsSilicate minerals are classified according to their crystalline structure. Thebasic structure is one silica atom surrounded by and strongly bonded by fouroxygen atoms (SiO4).l Olivines are a group of silicates that contain magnesium, iron and thesilicate group with minor amounts of nickel, manganese and calcium. Olivineis common in basalts, dolerite and gabbro.l Pyroxenes are chains of silicate (SiO4) units. The chains are linked bycations, especially calcium, iron and magnesium.l There are 30 or so types of mica, but only three are common — biotite,muscovite and phlogopite. Micas are sheet silicates. The forces between thesheets are weak and so the sheets can be split apart from one another easily.Mica is sometimes used to insulate electrical heating elements as it is notaffected by heat. Formica was invented as a synthetic substitute for mica inelectrical uses.

Table 1 Mohs’ scale of hardness

Hardness Mineral ExamplesHardest 10 Diamond

9 Corundum8 Topaz7 Quartz

Steel file 7.5

6 Feldspar5 Apatite

Steel pin or penknife 5.5

4 Fluorite3 Calcite

Copper coin 3.5

2 GypsumFinger nail 2.5

Softest 1 Talc

Einstein did not become instantly famous in1905; it took several years before he became aglobal icon. In 1915, while Europe was caught

up in the First World War, Einstein broadened hisspecial theory of relativity. His general theory ofrelativity predicted the effects of gravity on space,

time and light. In particular, it described how spacebecomes distorted near a massive object such as astar, so that light follows a curved path rather thantravelling in a straight line (Figure 1).

Its publication in wartime and the fact that it waswritten in German meant that few people read it.However, one person who did read it was the Britishastronomer Arthur Eddington. The story goes that itwas Eddington who brought Einstein to the world’sattention — though Einstein might have disagreed.

Eddington was a conscientious objector. As such,he should have spent the war in jail. Instead, he gotofficial permission to prepare for a trip to observe atotal eclipse of the Sun — a rare event. His intentionwas to verify Einstein’s general theory of relativity.Einstein felt that no such verification was needed, but

14 Catalyst

Charles Tracy

GCSE key wordsGravity

Alpha particlescattering

Nuclear fission

Physics connectionsD

etle

vva

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aven

swaa

y/S

PLLast year we celebrated the International Year of Physics — also known as Einstein Year. In the century since Einstein’sannus mirabilis (see CATALYST Vol. 16, No. 1) there has been a revolution in the study of physics. This article explores the links between some of the architects of this revolution.

Eddington went ahead as planned in 1919. Duringthe eclipse, Eddington measured the apparent shift inthe positions of stars that were beyond the Sun, astheir light rays were curved by its gravity. His resultswere in close agreement with Einstein’s predictions.

The international press were captivated. Onereporter suggested to Eddington that he was one ofonly three men who understood Einstein’s theory.Eddington replied, possibly ironically: ‘I am trying tothink who the third person is.’

Predicting particlesThat person could well have been Satyendra Bose,the Indian physicist who translated Einstein’s paperon the general theory of relativity from German intoEnglish. In 1924, Bose devised a theory for photons

and black body radiation. The theory came from amistake he made in a lecture: while trying to showthat theory could not predict the behaviour ofphotons, he accidentally showed that it could.

After some correspondence with Einstein, Bosedeveloped a new type of statistics that described thebehaviour of photons and similar particles. Theseparticles, which have whole-number values (0, 1, 2etc.) of a property called spin, are now known asbosons after Satyendra Bose.

Particles that are not bosons are called fermions.They have a spin of 1⁄2, 1 1⁄2, 2 1⁄2 and so on. This familyof particles includes protons, neutrons and electrons(Figure 2), and takes its name from Enrico Fermi,the Italian American physicist who built the f irstnuclear chain reactor in a Chicago squash court in1942. This was 4 years after he had escaped fromthe fascists at the time of his Nobel prize ceremony.After collecting his prize — for work on creatingradioactive isotopes through neutron bombardment— Fermi slipped out of the Stockholm Institute andmade good his escape.

Physics and facismAnother scientist who fled the fascists was Niels Bohr.Bohr stayed in his native Denmark for 3 years of theNazi occupation. But, in 1942, he escaped via Swedento England in the empty bomb rack of a British plane.He made his way to America and joined Fermi andothers in the Manhattan Project, building America’satomic bomb.

Before he left, Bohr had had a secret meeting withhis former pupil, the German physicist WernerHeisenberg. In the 1920s, Heisenberg had developeda mathematical method to describe the behaviour ofatoms. This was one of the foundations of quantummechanics, the basis of much of today’s physics.Later, during the Second World War, he was amember of the Uranium Club — the German grouptrying to develop a f ission weapon. In 1941, hetravelled to Copenhagen to meet his old friend Bohrand they went for a stroll after dinner. Their discussionremains a mystery. Did Heisenberg pass informationto Bohr, or did he try to enlist Bohr’s help with theUranium Club? We may never know for sure.

The Uranium Club also included the Germanphysicist Hans Geiger. During the Second World War,Geiger was an enthusiastic Nazi. This was totally atodds with the vehemently anti-fascist views of his

Photons are theparticles which carrythe energy ofelectromagneticradiation. Einstein used the idea ofphotons to explain thephotoelectric effect.

In his annus mirabilis,Einstein published threepapers. Their contentsinitiated moderncosmology andquantum mechanics —the foundations ofmodern physics.

Classical mechanics,developed by Newtonand others, is used todescribe large-scalephenomena. It does notwork on the scale ofatoms — quantummechanics must be usedinstead. It is the basis ofsemiconductors andtherefore much of ourtechnological world.

15April 2006

Apparent position of star

Distant star, hidden behind Sun

Starlight bent by Sun's gravity

Sun

Moon

Earth

Figure 1 One of theimplications of thegeneral theory ofrelativity is that space is distorted by largemasses like the Sun.Even light will alter itscourse. So stars appearout of position,something we can onlysee when the Sun’s lightis blocked by the Moonduring a solar eclipse

Magnetic field line

Figure 2 An electronhas spin. In a magneticfield, it can either spinclockwise (spin up) oranti-clockwise (spindown)

former tutor, Ernest Rutherford, for whom he hadperformed the famous alpha particle scattering exper-iments during 1908. In 1933, Rutherford had set upthe Academic Assistance Club to help Jewish scholarsescape the rising hatred in Germany.

Another of Rutherford’s students, James Chadwick,could have used some help in the previous war. Chad-wick left Manchester in 1914 to work with Geiger inBerlin. Unfortunately for him, the assassination ofArchduke Ferdinand on 28 June 1914 led to the out-break of the First World War. He was trapped inGermany and spent 4 years interned in the stables of aGerman racecourse. On his return home, he joinedRutherford at the Cavendish Laboratory in Cambridgewhere his work led to the discovery of the neutron in1932.

The age of the SunThe following year, the Russian physicist, GeorgeGamow, escaped a different tyranny by defectingfrom Stalin’s Soviet Union to America. Gamowworked on many things (including the genetic code),but is renowned for his description of the Hot BigBang. The paper, which he wrote with his studentRalph Alpher, was published in 1948. When he heardthat Hans Bethe was in town, Gamow could not resista little radiation joke: he asked Bethe to add his nameto the paper which became the Alpher, Bethe, Gamow(α,β,γ) paper.

Hans Bethe is best remembered for developing atheory that describes the nuclear processes inside theSun. His theory explained, at last, how the Sun couldstay so hot and have lasted so long — 4.5 billionyears, long enough for life to evolve on Earth. Only 50 years earlier, William Thomson (Lord Kelvin) hadestimated the age of the Sun as about 20 millionyears — 200 times too small.

Kelvin had described the Sun as an incandescentrock that had gained all its energy from ancientmeteor impacts. Somewhat boldly, in 1900 he hadstated that: ‘There is nothing new to be discovered inphysics now. All that remains is more and moreprecise measurement.’ Had Kelvin waited 5 years —for Einstein’s influential papers — he might have beenmore cautious.

Physics, past and futureHans Bethe died in 2005, the year in which wecelebrated 100 years of astute, committed and oftenbrave people who made the century of physics. Theirstories are as much about human endeavour, strengthand frailty as of laboratories and brassware. Thephysics they have developed would be unrecognisableto Kelvin. Physics is still changing. Who knows whatwill happen in the next 100 years?

Charles Tracy is a schools adviser in Hertfordshire and developsphysics teaching resources.

The Hot Big Bangtheory, generallyaccepted by scientiststoday, says that theuniverse exploded intoexistence, emergingfrom a single point,about 14 billion yearsago.

l Visit www.physics.org/evolution/evolution.aspfor an animated historyof physics.

16 Catalyst

Meh

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/SPL

Right: Computergraphic of the interiorof the Sun. Scientistsnow know that theSun is a massivenuclear fusion reactor

This is a good time of year to see predatorssuch as waterboatmen in action and thinkabout the way they deal with their prey.

Waterboatmen feed on a range of inverte-brates in ponds, lakes and even waterbutts. They swim on their backs, using

their third pair of oar-like legs. Their other two pairs oflegs are much shorter and are used for grabbing preyand manipulating it into the best position for feeding.They have stabbing piercing mouthparts. They usethese to inject saliva into their prey before sucking outthe contents.

Water boatmen usually hatch in April and May,from eggs laid either on the stems of pondweed or onhard surfaces, depending on the particular species.Water boatmen are about 15 mm long when fullygrown, as they are by July. When they first hatch, asminiature adults, waterboatmen are about 3 mmlong. They moult to about 6 mm, then 9 mm, then 12 mm, before their final moult.

Their prey depends on their age — a water flea(Daphnia) is worth catching if you are only 3 mm long,but larger waterboatmen prey on mosquito larvae andpupae, as well as other freshwater invertebrates.

You can watch waterboatmen in action if you havea pond that is safe enough to lie down by and peer in.But it can be more interesting to take them out of thepond to have a closer look.

Looking after predator and preyWaterboatmen can be kept in a glass jar with waterand a few sprigs of pondweed.

Water fleas are common in ponds in the spring andsummer but can also be bought from aquarists. If youcatch mosquito or midge larvae or pupae, rememberthat any adults which eventually hatch can bite!• Keep all animals in pond or rainwater.• Return the survivors to the pond from which theycame.• Adult waterboatmen have sharp mouthparts, whichcan pierce skin if you pick the insects up by hand.

Predation in actionPut a waterboatman in with some prey and watchwhat happens. What happens if the prey makescontact with the surface? What happens if you touchthe surface with a hair?

The waterboatman can also see prey below thewater surface. How good is it at locating prey thisway?

Once it has caught something, how does it hold it?Does it move the prey around at all? Can you seewhen it sticks its piercing mouthparts into its prey?How long does it feed for before discarding its prey?• What happens if you catch waterboatmen thathave fed well, rather than some that have not eaten ina while? You could keep waterboatmen isolated for aday before offering them prey.• What happens if you offer waterboatmen differentsorts of prey in different proportions? • Is there any difference in the way a waterboatmanbehaves when it has only one prey item in the tankwith it, compared with when there are lots?

Nigel Collins is an editor of CATALYST. His excitement at watchingwaterboatmen in action used to bemuse his students.

Predator and prey Try this

17April 2006

What you needl a means of catching predator and prey — if you don’t have a net, a plastickitchen sieve is finel some glass jars, or plastic lemonade bottles cut to make beakers, to keeppredator and preyl a glass dish or a plastic tray in which to see predators in action — it helps tohave a large surface areal a magnifying glass helps, although you can see a lot with the naked eyel plastic or metal spoons to transfer predator and preyl watch or timer

Box 1 Warning!Be careful near openwater. Do not go nearopen water on yourown and take carewhen watching or collecting waterboat-men and their preyfrom ponds or lakes.

Cla

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Mar

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A greater waterboatman hangs on the surface film,replenishing its air supply via the end of its oar-like abdomen

Some overwinter, butmany only survive theone season.

Waterboatmen are in a group called theHemiptera — the truebugs.

Number of waterboatmen

May June July0

100

200

300

Figure 1 Changes in waterboatmenpopulation, May toJuly

Psychology is an increasingly popular subjectat A-level and university, but many studentsare not sure what psychology is or what theywould be doing if they chose to studypsychology or to work as a psychologist. Jane Leadbetter tells us about her job as an educational psychologist.

Many television programmes show psycho-logists helping to solve crimes, commentingon families who are experiencing difficulties

or helping parents to control their difficult children.They all show psychologists applying their knowledgeof psychology to everyday situations, but what is thesubject of psychology about?

According to the British Psychological Societywebsite (www.bps.org.uk): ‘Psychology is the study ofpeople: how they think, how they act, react andinteract. Psychology is concerned with all aspects ofbehaviour and the thoughts, feelings and motivationunderlying such behaviour.’

Working as an educational psychologistEducational psychology is just one of the careers youcan choose if you have a degree in psychology (Box 1).It is a fascinating and worthwhile job as it focuses ontackling the problems encountered by young people ineducation. These may involve learning difficulties orsocial or emotional problems.

Educational psychologists normally work inschools, colleges, nurseries and specialist settings.They spend some of their time working with childrenand young people to assess their diff iculties andsuggest ways forward. They also spend a lot of time in

l Find out whichcombinations of A-levels are suitable forentry to a psychologydegree by going to theBritish PsychologicalSociety website(www.bps.org.uk) andinvestigating the careerssection.

18 Catalyst

Educational psychology

Box 1 Other types of psychologyInterested in psychology but noteducational psychology? Here aresome other types of psychologycourses listed by UCAS:l animal psychologyl applied psychologyl applied social psychologyl behavioural sciencel business psychologyl clinical psychologyl cognitive psychologyl cognitive sciencel counselling psychology

l developmental psychologyl European social psychologyl experimental psychologyl forensic psychologyl health psychologyl human psychologyl occupational psychologyl psychology of communicationsl social psychologyl sport psychologyFind out more about these andother courses on the UCAS website(www.ucas.com).

Your future

TopF

oto

Box 2 A typical working day

Nursery visitToday starts with a visit to a nursery. A child iscausing concern because he is not talking to otherchildren and does not interact socially with them.Perhaps this child has a speech or languageproblem?

After observing the child and playing alongsidehim in the nursery, I meet with the importantpeople in the child’s life. These are the child’sparents, the staff in the nursery and, in this case,perhaps a speech and language therapist, to discussthe particular worries and to suggest plans that canbe put into place.

I will probably make a follow-up visit to see thechild at home, to do a detailed assessment with thechild to find out the exact nature of the problem.The health services will also be contacted to checkon the child’s overall development. Psychologistsknow how children develop and can detect if a childis developing differently from the usual patterns.

School visitLater in the morning it’s a school visit to check howa class teacher is getting on with a plan to improvethe classroom environment. The behaviour of someboisterous and unruly pupils is causing problems.After observing how the classroom is arranged, how

the lessons are planned and how the teachermanages the children, I made suggestions abouthow things might be improved. The teacher hastried some of the suggestions and noticed that thelessons have improved. Psychologists know aboutfactors that affect behaviour and aggression andalso about ‘classroom ecology’.

Teacher sessionThe first afternoon session is with teachers, notchildren. Educational psychologists train teachersand other adults in schools. This afternoon is atraining session about children’s social andemotional needs. Other sessions have been aboutnew initiatives such as peer mentoring and pairedreading. After a training session there will be morevisits to help the staff to put the new systems inplace and ensure that they work properly.

Home visitLate afternoon is a home visit to a family whosechild has been referred for help. This visit is aboutfinding a suitable school. Some children need afresh start at another school or are in danger ofbeing permanently excluded from their currentschool. It is the time to find out the parents’ viewsand to compare the child’s behaviour across thevery different environments of home and school.

schools with teachers and others discussing problemsthat arise within the whole school, or within particularclasses, and, of course, with specific children whomay be causing concern.

The work is incredibly varied as it involves childrenand young people from the age of 2 to 19. Box 2describes a typical working day. More and moreeducational psychologists are working closely with other professionals who are concerned aboutchildren’s wellbeing outside schools.

How to become an educationalpsychologistTo be an educational psychologist, you must have adegree in psychology. You will need very high grades at A-level to gain a place on a suitable psychologycourse.

After graduating you must spend at least 2 yearsworking with children in a range of settings; manypeople train and then work as teachers to gain theexperience. Finally, you need to complete a 3-yeardoctoral course at university to qualify as an educa-tional psychologist. It’s a long training, but it’s worthit in the end!

Dr Jane Leadbetter is Tutor in Educational Psychology,University of Birmingham, and Senior Educational Psychologist,Birmingham LEA.

Speech and languagespecialists work withchildren who havedifficulty speaking,hearing orunderstanding spoken words.

l Get involved in anypeer listening and peermentoring groups atyour school.

l Go to www.psychnet-uk.com/games/games.htm to try somepsychological games.

l Find out about thelives and work of somefamous psychologists at www.psychnet-uk.com/training_ethics/psychologists.htm

19April 2006

Educational psychologistsoften assess the needs ofindividual children

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oto

The three oceanographic scientists — Harry

Bryden, Stuart Cunningham and Hannah

Longworth — who were involved in

investigating the Gulf Stream (pages 6–7)

relate something of their lives in science.

Scientific research often involves people workingtogether on problems, either directly in teams orby maintaining close contact with each other.

Scientists might work with engineers to create newinstruments for a space probe or with mathematiciansand software engineers as they model the workings ofcells or climate change.

20 Catalyst

The Royal Society is the UK Academy ofSciences. When he was made a Fellow the citation said that‘Professor HarryBryden is knowninternationally for the outstandingcontributions he hasmade through carefulobservation andinnovative analysis andinterpretation of datato the study of themeridional transport of heat in the ocean.’

A life in science

Oceanographers

Box 1 Stuart CunninghamThere is great debate about the relativeimportance of environment and genetics fordetermining what makes you you — nature versusnurture. My early life supports both sides. Myfather was an analytical chemist working in thesteel industry; perhaps I inherited some ‘science’genes from him. But I also grew up discussingscience — mainly physics and astronomy — on adaily basis. My mother’s side of the family were allboat builders. So there it is. Take one chemist andone boat builder’s daughter to make oneoceanographer!

After completing a BSc in astrophysics from the University of Edinburgh, I converted tophysical oceanography by completing a MSc at Bangor, before joining the Institute of

Oceanographic Sciences as a sea-goingoceanographer. At first I worked with the UK team in the World Ocean Circulation Experiment.This was a grand project, involving tens ofthousands of scientists from around the world,whose goal was to define the mean state of theocean over a 7-year period.

I have spent about 2.5 years of my life at sea allover the world on this and subsequent projects,making measurements of ocean temperature,salinity and currents.

I completed my PhD at the University of Liverpoolin 1997 and am now a principal investigator in an international programme to measure the role of the ocean in rapid climate change(www.noc.soton.ac.uk/rapidmoc).

Above: ProfessorHarry Bryden enjoys a mug of tea while an array of watersamplers is preparedfor lowering into theocean

Box 2 Hannah LongworthI have always enjoyed problem solving —this fuelled my early interest in science.When I was doing my GCSEs I had a workexperience placement at Merlewood, aresearch station on the southern edge ofthe Lake District. I met scientists studyingclimate change and had my firstexperience of fieldwork with a groupstudying soils.

I went on to study A-levels inmathematics, further mathematics,physics, chemistry and general studies.My degree choice of Oceanography withMathematics (BSc) at the University ofSouthampton was determined by thepotential to combine mathematicalanalysis of the dynamic ocean system with fieldwork at sea.

After graduating, I had the chance tostay on in Southampton at the NationalOceanography Centre, to work for a PhD.I am analysing oceanographicobservations made over the last 25 years at 26°N to try to buildup a picture of the Atlantic Meridional Overturning Circulation(MOC) over that time.

The current MOC monitoring project,which is funded for 4 years, involvesmore frequent observations, so this willprovide much more detail over the shortterm to complement the 25-year picture.

Both projects rely on cruises todeploy/recover moorings and measure in situ water properties. Going to seaprovides invaluable insight into thelimitations of the data but is an intenseexperience. For up to 6 weeks, scientists,technicians and the ship’s crew work ashift system, allowing almost continuous data collection and processing ofparameters, including watertemperature, salinity, velocity, nutrient,carbon and oxygen content.

I am looking forward to seeing theresults from the first year of monitoringand how they tie in with the fivehistorical sections.

The Centre for Ecology and Hydrology which used to be based atMerlewood, Grange-over-Sands, Cumbria, is now based at LancasterUniversity.

The project studying the ocean currents in thenorth Atlantic, described on pages 6–7, involves alarge international team of people. The principalinvestigator for the UK component is ProfessorHarry Bryden. He was born in the USA at Provi-dence, Rhode Island, and went on from high schoolto do a degree in mathematics at Dartmouth Collegein 1968.

Following a summer spent at an oceanographicresearch institute called Woods Hole, Harry appliedhis mathematics to oceanography, f irst with the US Navy and then when he became involved inresearch at Woods Hole. He worked on to complete a

PhD in 1975. During this time he was supported by aseries of research grants, but by 1983 Harry hadearned a permanent position as a Senior Scientist.

In 1993 Harry moved to England and in 1995 joinedthe Southampton Oceanography Centre. Last year hewas elected to become a Fellow of the Royal Society. AsProfessor of Physical Oceanography at SouthamptonUniversity, he teaches and conducts research withother scientists, including his fellow author StuartCunningham, and supervises the research of PhDstudents, such as Hannah Longworth. In Boxes 1 and 2Stuart and Hannah tell their own stories about howthey became involved in oceanography.

21April 2006

l You can read moreabout life and work on cruises to deploymoorings to monitorocean currents,temperature andsalinity atwww.soc.soton.ac.uk/rapidmoc/home.html byclicking on ‘News’ andchoosing a cruise.

Above: The water samplers are lowered into the oceanRight: Stuart Cunningham working on a profiler beforeit is attached to a mooring cable (see back page) A

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Hannah Longworth working on a sampler at 26°N

50 inch steel sphere float with navigation light

Titanium swivel inserted in buoy chain

Recording current meter

Surface

75 mProfiler stop with wire clamps

Profiler moves up and down wire

3400 m 3/16 inch wire

Profiler stop with wire clamps

Current meter

Ten 43 cm glass floats

Swivel

Release mechanism for retrieval

5 m chain

Railway wheels as �a heavy anchor

Not to scale

Bottom pressure recorder

3500 m

50 m depth

Scientists collect all sorts of information about the world’s

oceans. Temperature, salinity,currents, depth and otherparameters, such as amounts ofplankton, are all of interest tooceanographers and other scientists.Sometimes data are collected usingdevices towed behind ships;sometimes ships heave to and lowerinstruments on cables. Some dataare collected by instrumentsattached to submerged buoys,floating with the ocean currents.These surface every so often and

transmit the data they have loggedto laboratories far away, via satellite.

The international project describedon pages 6–7 involves instrumentsattached to wires up to 5000 metreslong. The wires are anchored to theseabed and buoys at the top, justunder the surface, hold themstraight. Some instruments motor up and down the wires every 2 days,taking measurements.

In all there are 22 moorings on thecontinental slope off Africa, eitherside of the Mid-Atlantic Ridge, andon the continental slope of the USA.

Logging data fromthe world’s oceans

Activitiesl You can watch a short film of the cruise to put out these

moorings by clicking onwww.noc.soton.ac.uk/rapid/sis/moc_monitor.php

l Plankton monitoring is described in CATALYST Vol. 15, No. 3.l You can find out more about datalogging carried out by

submerged buoys atwww.noc.soton.ac.uk/JRD/HYDRO/argo/op_argo.php

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