Continuing EducationAstronomy

 Astronomy

Continuing Education Program, Eastern Suburbs Community College

Michael Burton, 
School of Physics, UNSW, 
March-April 2005 
 
Michael Burton at the South Pole

Michael Burton at the South Pole

This web page can be found at  http://www.phys.unsw.edu.au/conted/astronomy.html

Introduction:

Humans have always had a fascination with the stars.  A glimpse of the Milky Way, seen on a dark night, invokes a sense of wonder about who we are and where we came from.  This course is designed to provide an introduction to our current understanding of our place in the Universe.  It will be delivered as a series of multi-media style presentations, with extensive use of some of the spectacular images that astronomy provides.  Lectures will describe the Solar System, and the varied and fascinating worlds within it, as revealed by space probes sent to explore the planets.  They will then describe our Galaxy, the stars and nebulae within it, and the processes that cause stars to form and die.  Finally, we will discuss the Universe of galaxies, the fundamental building blocks of nature.  A session on astronomy on the internet will be given, with a hands-on demonstration of the many resources that are publicly available on the web, to aid individual exploration of them.  Finally, weather permitting, the course will include a practical session showing how telescopes work and viewing the night sky using the UNSW observatory.
 

The Lecturer:

Dr Michael Burton is a lecturer in astronomy and physics in the School of Physics of UNSW.  He is an active research astronomer, and the author of over 200 scientific papers.  He specialises in infrared astronomy, with its particular application to our understanding of the environment in  which star formation occurs, obscured cocoons inside vast clouds of molecular gas and dust.  He has been actively involved in the development of astronomy in Antarctica, playing a lead role in the pioneering activities that Australia is undertaking at the South Pole.  He is co-chair of the science steering committee for Joint Australian Centre for Astrophysical Research in Antarctica.  He is also project scientist for the 22-m diameter Mopra millimetre-wave telescope near Siding Spring Observatory, the largest in the Southern Hemisphere.  Michael also devotes considerable energies to the public popularisation of science.  He was a founder of 'Science in the Pub', a production which features eminent scientists discussing topics of public interest in the environment of the local pub, and which was awarded the Eureka Prize for the Promotion of Science in 2000.

Timetable:

 
Week
 Date Subject
1
 March 15 An overview of the Universe
2
 March 29 Observing or Astronomy with a Computer
3
 April 5 Astronomy with a Computer or Observing

 

Lecture Links:

 

Books:


As a result of the huge demand for popular astronomy courses at US universities and colleges there are a number of superb textbooks on astronomy, updated almost annually, which contain fantastic images, associated CDs and other teaching resources. They are generally written at a descriptive level, with mathematical equations placed inside text boxes. Such books will make an excellent reference source and can be used by a wide range of students and educators. You can order these books through the UNSW bookshop. Some suitable books, and web addresses for further information, include:

http://www.whfreeman.com/astronomy/master.htm
  http://jws-edcv.wiley.com/college/
  http://www.harcourtcollege.com/astro/fraknoi/ http://brookscole/astronomy
 
  http://www.wadsworth.com/
 
 

Magazines:
 
Australian Sky and Telescope http://www.austskyandtel.com.au
Sky and Space http://www.skyandspace.com.au/public/home.ehtml
New Scientist http://www.newscientist.com/
Scientific American http://www.scientificamerican.com/

Software:

Planetarium Software that may be of interest:

Notes from an Astronomer:

http://cfa-www.harvard.edu/seuforum/opis_tour_earth.htm

This article by Andrew Fraknoi and Sherwood Harrington of the Astronomical Society of the Pacific is a great background piece. Take a trip from Earth to the farthest reaches of the Cosmos! Extracts from it are given below:

THE SOLAR SYSTEM

To begin at home, our Earth is a member of the family of planets and moons known as the solar system. Orbiting our star, the Sun, are nine planets and their more than 40 satellites, each a unique world with its own special characteristics. Assorted cosmic debris - in the form of comets, asteroids, and smaller chunks called meteoroids - also share our system with us.

THE MILKY WAY GALAXY

Beyond the solar system, there is a vast expanse of space, with an occasional grain of dust or elemental atom floating in the dark emptiness. The nearest other star system - Alpha Centauri, best seen from the Earth's southern latitudes - is so far away that Voyager, the fastest spacecraft our species has built, would take about 100,000 years to reach it. Even beams of light, which travel at a phenomenal one billion kilometres an hour, take a little over four years to make the journey between these two systems.

BEYOND THE MILKY WAY

Beyond our own Galaxy lie even larger and emptier regions of what we call "intergalactic space". These areas are so unpopulated that on average you might run across only a single atom in every cubic metre of space. Accompanying our Milky Way are several small "satellite" galaxies, the largest of which are the Magellanic Clouds. They are 150,000 to 200,000 light years away and give astronomers (in the Southern Hemisphere, where the clouds are visible) an excellent opportunity to study another system of stars that has evolved more or less separately from our own.

THE LARGEST OF SCALES

Very recently, astronomers have discovered that even the grand groups of galaxies are not randomly distributed. Galaxy groups seem strung out in vast rounded filaments, separated by enormous voids with relatively few galaxies. This structure, which we are just beginning to glimpse, may hold important clues to the unimaginably violent processes that created the universe.
 

At a particular instant roughly 13 billion years ago, all the matter and energy we can observe, concentrated in a region smaller than a 5c piece, began to expand and cool at an incredibly rapid rate. By the time the temperature had dropped to 100 million times that of the sun's core, the forces of nature assumed their present properties, and the elementary particles known as quarks roamed freely in a sea of energy. When the universe had expanded an additional 1,000 times, all the matter we can measure filled a region the size of the solar system.

At that time, the free quarks became confined in neutrons and protons. After the universe had grown by another factor of 1,000, protons and neutrons combined to form atomic nuclei, including most of the helium and deuterium present today. All of this occurred within the first minute of the expansion. Conditions were still too hot, however, for atomic nuclei to capture electrons. Neutral atoms appeared in abundance only after the expansion had continued for 300,000 years and the universe was 1,000 times smaller than it is now. The neutral atoms then began to coalesce into gas clouds, which later evolved into stars. By the time the universe had expanded to one fifth its present size, the stars had formed groups recognisable as young galaxies. When the universe was half its present size, nuclear reactions in stars had produced most of the heavy elements from which terrestrial planets were made. Our solar system is relatively young: it formed five billion years ago, when the universe was two-thirds its present size. Over time the formation of stars has consumed the supply of gas in galaxies, and hence the population of stars is waning. Fifteen billion years from now stars like our sun will be relatively rare, making the universe a far less hospitable place for observers like ourselves.

From The Evolution of the Universe by P. James E. Peebles, David N. Schramm, Edwin L. Turner and Richard G. Kron, Scientific American Special Edition, 'The Magnificent Cosmos', March 1998. 

The basic difference between a star and a planet is that a star emits light produced in its interior by nuclear 'burning', whereas a planet only shines by reflected light. The Sun is our own special star yet, as stars go, it is a very average one. There are stars far brighter, fainter, hotter and cooler than the Sun. Basically, however, all the stars we can see in the sky are objects similar to the Sun. They are great balls of gas held together by their own gravity. The force of gravity is continually trying to force the Sun towards its centre and if there were not some other force counteracting it the Sun would collapse. The necessary outward pressure is produced by the radiation from the nuclear energy generation in the Sun's interior.

Stars form from condensations within huge interstellar gas clouds. These contract due to their own gravitational pull. The star settles down to a long period of stability while the hydrogen at its centre is converted into helium with the release of an enormous amount of energy. This stage is called the main-sequence stage, a reference to the classical Hertzsprung-Russell (HR) diagram, which relates the stellar temperature (or colour) to the luminosity (or 'magnitude'). Most stars lie in a well-defined band in the HR diagram and the only parameter that determines where they lie is the star's mass.

The more massive a star is the quicker it 'burns' up its hydrogen and hence the brighter, bigger and hotter it is. The rapid conversion of hydrogen into helium also means that the hydrogen gets used up far sooner for the massive stars than for the lighter ones. For a star like the Sun the main-sequence stage lasts about 10 billion years whereas a star 10 times as massive will be 10,000 times as bright but will only last for 100 million years. On the other hand, stars a tenth the mass of the Sun have a lifetime far greater than the current age of the Universe!

Stars do not all evolve in the same way. Once again it is the star's mass that determines how they change. Stars similar in mass to the Sun 'burn' hydrogen into helium in their core during the main-sequence phase but eventually there is no hydrogen left there to provide the necessary radiation pressure to balance gravity. The core of the star thus contracts until it is hot enough for helium to be converted into carbon. The hydrogen in a shell continues to 'burn' into helium but the outer layers of the star have to expand. This makes the star appear brighter and cooler and it becomes a 'red giant'.

During the red giant phase a star often loses much of its outer layers, blown away by the radiation coming from below. In the more massive stars the carbon may be 'burnt' to even heavier elements but eventually all energy generation will fizzle out and the star will collapse to what is called a 'white dwarf', if its mass is less than five times that of the Sun.

There are very few stars with masses greater than this but their evolution ends in a spectacular fashion. They go through their evolutionary stages very quickly compared to the Sun. They expand enormously, becoming red 'supergiants'. During this stage many different chemical elements will be produced in the star and the central temperature will approach 100 million Kelvin.

For elements of lower atomic number than iron the addition of more nucleons to the nucleus releases binding energy and so yields a small contribution to the balance inside the star between gravity and radiation. However, to add nucleons to an iron nucleus requires energy and so once the core of the star has been converted to iron no more energy can be extracted. The star's core then has no resistance to the force of gravity and it contracts rapidly. The protons and electrons combine to produce a core composed of neutrons and a vast amount of gravitational energy is released. This energy is sufficient to blow away all the outer parts of the star in a violent explosion and the star becomes a supernova. The light of this explosion shines as bright as an entire galaxy for a few days. During this phase all the elements with atomic weights greater than iron are formed in the expanding shell and are blown out into interstellar space. The central core of neutrons is left as a neutron star, which could be a pulsar, or even collapse to a black hole.

What is remarkable about this process is that the first stars were composed almost entirely of hydrogen and helium, without oxygen, nitrogen, iron, or any of the other elements that are necessary for life. These were all produced inside massive stars and then spread throughout space by such supernovae events. We are made up of material that has been processed at least once, and probably several times, inside stars-we are 'stardust'.

Adapted from Royal Greenwich Observatory Information Leaflet No. 7: 'What is a Star?' http://www.nmm.ac.uk/server/show/conWebDoc.299
 
 

A cloud of interstellar gas (the "solar nebula") is disturbed and collapses under its own gravity. The disturbance could have been caused, for example, by the shock wave from a nearby supernova. As the cloud collapses, it heats up and compresses in the centre, forming a protostar. Most of the gas flows inward and adds mass to the protostar. However the cloud is rotating and centrifugal forces (and the conservation of angular momentum) prevent all the gas from reaching the protostar. Instead, it forms an "accretion disk" around it. The gas cools off enough for the metal, rock and (far enough from the forming star) ice to condense out into tiny particles of dust. The dust particles collide with each other and form into larger particles. This goes on until the particles get to the size of boulders or small asteroids. Larger particles then are big enough to have a non-trivial gravity and their growth accelerates, forming proto-planets. After about 1 million years the nebula has cooled and the star generates a strong wind, which sweeps away all of the remaining gas. If a proto-planet was large enough its gravity would pull in the nebular gas, and it would become a gas giant (e.g. Jupiter). If not, it would remain a rocky or icy body (e.g. Earth). Eventually, after ten to a hundred million years, we end up with ten or so planets, in stable orbits. These planets and their surfaces may be heavily modified by the last, big collision they experience, and they are scarred by impact craters from collisions with smaller bodies.

Planetary structure is determined by chemical differentiation whilst the planet is still molten. Dense elements sink to the core of the planet and light elements rise to the surface. After the planet cools and solidifies this internal structure remain frozen.

Our solar system consists of the Sun; the nine planets, sixty-six satellites of the planets, a large number of small bodies (the comets and asteroids), and the interplanetary medium. The inner solar system contains the Sun, Mercury, Venus, Earth and Mars and the outer solar system contains Jupiter, Saturn, Uranus, Neptune and Pluto.

The orbits of the planets are ellipses with the Sun at one focus, though all except Mercury and Pluto are very nearly circular. The orbits are all more or less in the same plane (called the ecliptic), and are in the same sense. All but Venus and Uranus also rotate in the same sense as the orbit.
 

The Sun is an ordinary star, one of more than 100 billion stars in our galaxy. It is by far the largest object in the solar system, containing more than 99.8% of its mass (Jupiter contains most of the rest). The Sun is, at present, about 75% hydrogen and 25% helium by mass; everything else ("metals") amounts to only 0.1%. This changes slowly over time as the Sun converts hydrogen to helium in its core. Conditions in the Sun's core are extreme. The temperature is 15 million Kelvin and the density 150 times that of water. The Sun's energy output (4 x1026 Watts) is produced by nuclear fusion reactions in the core. Each second about 700 million tons of hydrogen are converted to about 695 million tons of helium and 5 million tons of energy in the form of gamma rays. As the gamma-rays travels outwards, their energy is continuously absorbed and re-emitted at lower and lower temperatures so that by the time they reach the surface, they are primarily visible light. The surface of the Sun, called the photosphere, is at a temperature of about 6,000 K. Sunspots are "cool" regions, only 4,000 K (they look dark only by comparison with the surrounding regions). Sunspots can be very large, as much as 50,000 km in diameter. Sunspots are caused by interactions with the Sun's magnetic field. In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind, which travels throughout the solar system at about 450 km/sec. The solar wind can have dramatic effects on the Earth ranging from power line surges, to radio interference, to beautiful aurora.

The Sun's output is not entirely constant. Nor is the amount of sunspot activity. There was a period of very low sunspot activity in the latter half of the 17th century called the Maunder Minimum. It coincided with an abnormally cold period in northern Europe sometimes known as the Little Ice Age. Since the formation of the solar system the Sun's output has increased by about 40%. It is now about 4.5 billion years old and will continue to radiate "peacefully" for another 5 billion years or so (although its luminosity will approximately double in that time). But eventually it will run out of hydrogen fuel and be forced into radical changes, which will result in the total destruction of the Earth (and probably the creation of a planetary nebula).
 

The Earth is divided into several layers which have distinct chemical and seismic properties: The crust varies considerably in thickness; it is thinner under the oceans, thicker under the continents. The inner core and crust are solid, the outer core and mantle layers are plastic or semi-fluid. The core is probably composed mostly of iron though some lighter elements may be present too. Temperatures there may be as high as 7,500 K, hotter than the surface of the Sun. The Earth's crust is divided into several separate, solid, 'tectonic' plates, which float around independently on top of the hot mantle below.

The Earth's surface is very young. In the relatively short (by astronomical standards) period of 500 million years or so, erosion and tectonic processes destroy and recreate most of the surface and thereby eliminate almost all traces of earlier geologic surface history (such as impact craters). Thus, the very early history of the Earth has mostly been erased. The Earth is about 4.6 billion years old, but the oldest known rocks are about 4 billion years old and rocks older than 3 billion years are rare. The oldest fossils of living organisms are about 3.5 billion years old. There is no record of the critical period when life was first getting started.

Earth has a modest magnetic field produced by electric currents in the core. The interaction of the solar wind, the Earth's magnetic field and the Earth's upper atmosphere causes the auroras. The Earth's magnetic field and its interaction with the solar wind also produce the Van Allen radiation belts, a pair of doughnut shaped rings of ionized gas (or plasma) trapped in orbit around the Earth, extending from 7,500 km to 40,000 km in altitude.
 
 

Web Sites of Interest

(a) Institutions

Department of Astrophysics, University of New South Wales

http://www.phys.unsw.edu.au/astro.html

One of Australia's leading university research groups in astronomy, with particular strengths in star formation, cosmology, infrared astronomy, millimetre-wave astronomy and Antarctic astronomy.
 
 

School of Physics, University of New South Wales

http://www.phys.unsw.edu.au/

One of Australia's premier physics groups, undertaking a wide range of research activities, including condensed matter physics, biophysics, environmental physics and astrophysics.
 
 

Astronomical Society of Australia

http://www.atnf.csiro.au/asa_www/asa.html
 

The society for professional astronomers in Australia.
 

Australian Astronomy Portal

http://www.astronomy.org.au/ 

Run by the Astronomical Society of Australia, a starting point for learning about astronomy in Australia.

Anglo Australian Observatory

http://www.aao.gov.au/

Australia's national optical / infrared observatory. Includes an excellent source of astronomical images taken by David Malin.
 
 

Australia Telescope National Facility

http://www.atnf.csiro.au/

Australia's national radio observatory.
 
 

Hubble Space Telescope

http://www.stsci.edu/

Home page for the Hubble Space Telescope, including access to all the news releases, pictures and extensive educational resources.
 

NASA (National Aeronautics and Space Administration)

http://www.nasa.gov/

Starting point for a truly vast ranges of resources!  Of particular interest might be the link to Human Spaceflight.
 
 

(b) Educational Resources

Amazing Space

http://amazing-space.stsci.edu/

A set of web-based activities designed for classroom use. Includes


AstroCappella

http://www.astrocappella.com/

AstroCappella is a marriage of astronomy and music, developed by astronomers and professionally recorded by the Chromatics. It includes the following downloadable songs:

A free CD can be obtained by teachers containing all the songs. The web pages not only contain the words, which tell the story behind the subject matter, but also contain an activity sheet and include supplementary information, images etc.
 

Astronomy Notes

http://www.astronomynotes.com/

Lecture notes for a complete astronomy course, together with images, from Nick Strobel of Bakersfield College. A quite remarkable resource. It contains the following sections:


Astronomy Picture of the Day

http://antwrp.gsfc.nasa.gov/apod/astropix.html

Updated daily - a picture of somewhere interesting in the Universe, with a brief description from a professional astronomer.
 

Earth and Moon Viewer

http://www.fourmilab.to/earthview

See any part of the Earth and Moon, at any time of the day or night, from space!  You can view the Earth as a map, as it is seen from the Sun or the Moon, above any particular location, or from a satellite.  This is a great piece of software to play with!

Great Debates in Astronomy

http://antwrp.gsfc.nasa.gov/debate/debate.html

Classic debates in astronomy on major issues. A useful reference not only for the subject at hand, but for the history of science, and also for understanding the working of the scientific method. Debates include:


Imagine the Universe

http://imagine.gsfc.nasa.gov

A service from the high-energy astrophysics group at NASA's Goddard Space Flight Center. The site is dedicated to a discussion about our Universe; what we know about it, how it is evolving, and the kinds of objects and phenomena it contains. Just as importantly, it also includes discussion on how scientists know what they know, what mysteries remain, and how we might one day find the answers to them.
 

Java Applets

http://zebu.uoregon.edu/nsf/demo.html

This is a demonstration page of various physics and astronomy Java applets from the University of Oregon Physics Department. They recommend a minimum size of 800x600 to view these resources. The Java applets which are referenced have been certified to work under Netscape version 3.0 (and higher) on a Windows 95 platform or in the SUN/Solaris OS. Java under Netscape on a Mac still exhibits problematical behaviour. Please be patient when loading the applet pages - if funny behaviour occurs under Windows95 try flushing Netscape's Cache. Note that hitting the reload button will often cause the applet to be repainted incorrectly. This behaviour is beyond their control. In this case it's best to go back to the demo page, flush the cache, and click on the applet link again. Referenced animations are all in MPEG format so an MPEG viewer is required to view them.
 

J-Track
NASA tracking software J-track allows you to see where any satellite is at any time!  It works using java applets, so should work on your machine once you download the database. In particular, you can find out where the Hubble Space Telescope, the Mir space station, the Space Station and the Space Shuttle (during missions) are right now, watch their progress across the surface of the Earth and see when they will next be visible from your location.  The 3D version is particularly useful for illustrating orbital mechanics, by observing the distribution of satellites used for specific purposes (eg astronomy-IUE, HST, ROSAT, Chandra; communications, iridium, military-GPS; weather-GOES).

http://liftoff.msfc.nasa.gov/RealTime/JTrack/Spacecraft.html Satellite location over Earth map

Mouse controls:
Click on craft Change orbital data in lower right 
Ctrl+Click on craft Toggles on/off ground trace
Shift+Click on craft Goes to web page about craft
Click+hold on map Display first visible at longitude

http://liftoff.msfc.nasa.gov/RealTime/JTrack/3D/JTrack3D.html 3D distribution of satellites

 Mouse controls:
Shift+Click Zoom In
Ctrl+Click Zoom Out
Click on satellite show trace
Click in list show trace
Drag rotate in 3d

 

Origins Program (NASA)

http://origins.stsci.edu/

The Origins Program is funded by NASA for the scientific study of the long chain of events from the birth of the universe in the Big Bang, through the formation of galaxies, stars and planets, the chemical elements of life to the profusion of life on Earth and possibly elsewhere. This link is the public gateway to the program. There are fact sheets on the following:

There are on-line tutorials for:


Project Astro (Astronomical Society of the Pacific)

http://www.astrosociety.org/education/astro/project_astro.html

Astronomers and educators as partners for learning. Project ASTRO began in 1993 as a pilot project in California, pairing professional and amateur astronomers with the classroom. It combines the expertise of educators and scientists in a long-term collaborative. The partners are trained together in workshops that emphasise hands-on activities with family and community involvement. Some sample classroom activities include:


Project CLEA (Contemporary Laboratory Exercises in Astronomy)

http://www.gettysburg.edu/academics/physics/clea/CLEAhome.html

Project CLEA develops laboratory exercises that illustrate modern astronomical techniques using digital data and colour images. They are suitable for high schools. Each CLEA laboratory exercise includes a dedicated computer program, a student manual, and a technical guide for the instructor. The CLEA labs run under Windows on PC's, or on Macintosh computers (but work best on PC's). The exercises can be down-loaded for free. Of particular interest may be the following exercises:

Others include:


Relativity on the World Wide Web
http://www.math.washington.edu/~hillman/relativity.html (broken link)

A starting point for learning about Relativity, with a comprehensive listing of sites on the subject.  Broken down into three main sections:

Science Education Gateway

http://cse.ssl.berkeley.edu/segway/

The Science Education Gateway is a collaborative NASA project, which brings together the expertise of NASA scientists, science museums, and educators to produce Earth and space science curricula for classroom and public use via the World Wide Web. This SEGway web site is designed to help teachers locate and identify the resources they can use best and that fit their local curriculum and National Science Education Standards. Web-projects are divided into three main categories, each containing several web-based tutorials:


Solar System Exploration

http://education.jpl.nasa.gov/educators/lp5-12.html

Lesson plans from NASA JPL (some need to be down-loaded in PDF format) regarding the Solar System. These may help you find ways to integrate the study of Space Science into the curriculum. The lesson plans are classified by grade level.


Royal Greenwich Observatory Information Leaflets
http://www.rog.nmm.ac.uk/leaflets/index.html

An excellent source of concise information about a wide variety of astronomical topics.  The notes are divided into the following sections, each containing many leaflets within them:


The Astronomy Café

http://www.astronomycafe.net/

Ask the Astronomer! Sten Odenwald will attempt to answer your question on astronomy. There is also an archive of questions that he's answered. There's a good chance he may already have answered yours! Get your pupils to send him a question!
 

The Nine Planets

http://www.nineplanets.org/

The Nine Planets is an overview of the history, mythology, and current scientific knowledge of each of the planets and moons in our solar system. Each page has text and images, some have sounds and movies, and most provide references to additional related information.
 

The Universe as Humans see it

http://www.geocities.com/Athens/Atlantis/7119/UniPicture.htm (link broken)

A short synopsis of our changing view of the Universe, including a brief overview of the ideas of the Greeks (Aristotle and Ptolemy) and the Renaissance astronomers of Europe (Copernicus, Kepler, Newton), followed by a more in-depth view of 20th century cosmology, including the expanding universe, the steady-state universe and the Big Bang.
 

Treasure Trove of Science

http://www.treasure-troves.com

Eric Weissen's encyclopedia of science, with particular volumes for physics and for astronomy. A comprehensive reference source.
 

Visible Earth
http://www.visibleearth.nasa.gov/

A searchable directory of images, visualisations and animations of the Earth.  Contains some truly spectacular images of the Home Planet, and helps one to appreciate the fragile beauty of the Earth as well the interconnected ecology of its parts.  Created from a range of satellites operating as part of NASA's "Mission to Planet Earth".  Divided into several sections:


Welcome to the Planets

http://pds.jpl.nasa.gov/planets

This is a collection of many of the best images from NASA's planetary exploration program.
 
 
 
 


 
 

Further Information

Contact
 
 

[Search | School Information | Physics Courses | Research | Graduate]
[ Resources | Physics! | Physics Main Page | UNSW Main Page ]

School of Physics - The University of New South Wales - Sydney Australia 2052
Site Comments: physicsweb@phys.unsw.edu.au
© School of Physics - UNSW 2001