UNREPORTED COMMON PROPER MOTION BINARY STARS (NEW CHALLENGES FOR AMATEUR ASTRONOMERS Book 3)
It is organized with a twenty-eight day observing diary, and features tips on recording observations and helpful advice on Lunar photography. The Moon Map 40" x 27" is a highly detailed look at the Moon's near side. Hundreds of physical features—all of which can be seen with binoculars or a telescope—are labeled and indexed, including the locations of Lunar landings. The sidebar text offers practical guidance on moonwatching and highlights spectacular features. A smaller map of the far side completes this comprehensive depiction of the Lunar surface.
The poster is double-sided, showing how the Moon is seen from both the southern and northern hemispheres. Matloff More Telescope Power: Want to explore Mars? With More Telescope Power , you can do all of that and more! Filled with dozens of all-new stargazing projects and observing activities, this detailed guide also contains plenty of helpful illustrations such as finder charts, lunar and solar eclipse tables, diagrams, and photos. To mark the occasion, Curator Yip regrouped some forty pieces of the exhibits by their nature and compiled this beautifully conceived large format book.
The first chapter introduces starmaps and records related to the Chinese sky. The second details instruments for observation in Ancient China. The third focuses on ancient legends and relics related to astronomy. The fourth mainly introduces how ancient Chinese made use of the Sun, Moon, stars, clepsydras and joss sticks to tell time.
And where today is the Prince of the tower? Today they travel around the world as cultural ambassadors. They show visitors from all walks of life the beauty and elegance of science and art in the ancient world. And this echoes the meaning of the title of this book "Moving Stars, Changing Scenes. Leon Golub and Jay M. Unlike the myriad points of light we gaze at in the night sky, our nearest star allows us to study the wonders of stellar workings at blindingly close range—from a mere 93 million miles away.
And what do we see? In this book, two of the world's leading solar scientists unfold all that history and science—from the first cursory observations to the measurements obtained by the latest state-of-the-art instruments on the ground and in space—have revealed about the Sun. Following the path of science from the very center of this ,,,,,,megawatt furnace to its explosive surface, Nearest Star invites readers into an open-ended narrative of discovery about what we know about the Sun and how we have learned it.
How did the Sun evolve, and what will it become? What is the origin of its light and heat? How does solar activity affect the atmospheric conditions that make life on earth possible? These are the questions at the heart of solar physics, and at the center of this book. Having made optical solar observations with many solar telescopes and in the rockets and satellites, the authors bring their extensive personal experience to this story of how astronomers study the Sun, and what they have discovered about phenomena from eclipses to neutrinos, space weather, and global warming.
Richly illustrated with an assortment of pictures from the latest solar missions and the newest telescopes. Tom Standage The Neptune File: As well, thirty sky charts, each with a clear plastic overlay, feature the important stars and constellations. Features the superb images of world-renowned astrophotographer, Axel Mellinger.
New Frontiers in the Solar System: An Integrated Exploration Strategy Request a copy http: Solar system exploration is that grand human endeavor which reaches out through interplanetary space to discover the nature and origins of the system of planets in which we live and to learn whether life exists beyond Earth. It is an international enterprise involving scientists, engineers, managers, politicians, and others, sometimes working together and sometimes in competition, to open new frontiers of knowledge. It has a proud past, a productive present, and an auspicious future.
This survey was requested by the National Aeronautics and Space Administration NASA to determine the contemporary nature of solar system exploration and why it remains a compelling activity today. A broad survey of the state of knowledge was requested. In addition NASA asked for the identification of the top-level scientific questions to guide its ongoing program and a prioritized list of the most promising avenues for flight investigations and supporting ground-based activities.
Fifteen years on from the highly praised The New Physics , new scientific advances have led to a dramatic reappraisal of our understanding of the world around us, and made a significant impact on our lifestyle. Underpinning all the other branches of science, physics affects the way we live our lives and ultimately how life itself functions.
This fully rewritten new edition investigates key frontiers in modern physics. Exploring our universe, from the particles within atoms to the stars making up galaxies, it reveals the vital role invisible mechanisms play in the world around us, and explains new techniques, from nano-engineering and brain research to the latest advances in high-speed data networks and custom-built materials.
Written by leading international experts, each of the nineteen self-contained chapters will fascinate scientists of all disciplines, and anyone wanting to know more about the world of physics. The principles of quantum mechanics are the basis of everything in the physical world—from atoms to stars, from nuclei to lasers. Quantum paradoxes and the eventful life of Schroedinger's Cat are explained, along with the Many Universe explanation of quantum measurement in this newly revised edition of The Quantum Universe Updated throughout, the book also looks ahead to the nanotechnology revolution and describes quantum cryptography, computing and teleportation science fiction.
George Gamow's Classic Mr. The mild-mannered bank clerk with the short attention span and vivid imagination has inspired, charmed and informed since the publication of Mr. Tompkins in Paperback in Completely revised and updated, this new version retains the original British charm while introducing Mr. Tompkins to some of the most important developments that have taken place in recent years, including Einstein's relativity and bizarre effects near the speed of light, the birth and death of the universe, blackholes, quarks, space warps and antimatter, the fuzzy world of the quantum and the ultimate demolition derby of atom smashers.
Winner of the "Best French Astronomy Book " and written from the perspective of one of the pioneers of this scientific adventure, New Worlds in the Cosmos describes the development of the modern observing technique that has enabled astronomers to find so many planets orbiting around other stars. It reveals the wealth of new planets that have now been discovered outside our solar system, and the meaning of this finding as it concerns other life in the Universe.
In , together with Didier Queloz, he discovered the extrasolar planet 51 Peg b around a main sequence star, and has discovered many more since. Night Sky Atlas combines clear, accurate star maps with reliable and informative text. Sturdy binding makes it suitable for outdoor use. Cover flaps can be used as page-markers, and the sewn binding allows the atlas to be opened flat.
The star maps are drawn with black stars on a white background, allowing observers to pencil in their own observations the high quality paper can withstand repeated use of an eraser! The book begins by presenting the whole sky in a series of six maps, showing stars down to magnitude 5. Opposite each map is a photo-realistic image that shows how the same portion of sky looks to the naked eye, allowing less-experienced observers to quickly find specific objects of interest. This book is a down-to-earth guide for finding astronomical features in the Northern Hemisphere without the aid of expensive telescopes or complicated sky maps.
Organized chronologically, a simple color photo of the night sky shows which direction to face and where to look for such planets as Venus, Mars, Saturn, and Jupiter. Chapters are divided into months and include the Moon's phases, dates of planetary and star positions, and specific times to watch. Includes historical details and phenomena such as lunar and solar eclipses, constellations, and comets, as well as historical tidbits and useful tips.
The first three editions of NightWatch sold more than , copies, making it the top-selling stargazing guide in the world for the last 20 years. The key feature of this classic title is the section of star charts that are cherished by backyard astronomers everywhere. Each new edition has outsold the previous one because of thorough revisions and additional new material. The fourth edition has revisions in every chapter, including:. The famous charts, ideal for stargazers using a small telescope or binoculars. A complete update of the equipment section, including computerized telescopes.
An enlarged photography section, including how-to instructions for using the new generation of digital cameras for astronomical photography, both with and without a telescope. The tables of future solar and lunar eclipses, planetary conjunctions and planet locations, updated through This edition includes for the first time star charts for use in the southern hemisphere.
There are also dozens of new photographs throughout the book that show the latest thrilling discoveries made by current space observatories and probes.
General Astronomy/Print version
This challenging collection of problems is organized into seven carefully crafted, thoughtful chapters on the Sun and the nature of the solar system; the motion of the planets; the Sun, Earth, and Moon; the sky as observed from the rotating, revolving Earth; other planets, their satellites, their rings; asteroids, comets, and meteoroids; and the radiations and telescopes. From question 1, "List characteristics of the solar system that are major clues in devising a hypothesis of its origin and evolution," through question , "Give a brief list of the contributions of radio and radar technologies in lunar and planetary astronomy," the problems range in difficulty from ones requiring only simple knowledge to ones requiring significant understanding and analysis.
Many of the answers, in turn, illuminate the questions by providing basic explanations of the concepts involved. Regent Distinguished Professor of Physics and Astronomy at the University of Iowa and a "founding father" of the space age, Van Allen formally retired from teaching in He recently celebrated his 90 th birthday and remains an active researcher, arriving at his office daily to examine data from space-based instruments of his own design on board Pioneer 10 and earlier spacecraft.
Using an original approach, Mauro Dardo recounts the major achievements of 20th century physics--including relativity, quantum mechanics, atomic and nuclear physics, the invention of the transistor and the laser, superconductivity, binary pulsars, and the Bose-Einstein condensate--as each emerged. His year-by-year chronicle, biographies and revealing personal anecdotes help bring to life the main events since the first Nobel Prize was awarded in Noted physicist Henning Genz tells a history of emptiness as explored in physics and philosophy for the nonscientist, using stories, illustrations, and analyses to elucidate complex ideas.
Genz also moves behind the stories to explain how the study of nothingness has both contributed to and benefited from major scientific discoveries, including Big Bang cosmology, and also explores space time, ur-matter, the Higgs field, relativity, and quantum mechanics. At the core of the atom, enshrouded by electrons, lies the nucleus. The discovery of the nucleus transformed the past century and will revolutionize this one. Though many persons associate nuclear physics with weapons of mass destruction, it is an exciting, cutting-edge science that has helped to save lives through innovative medical technologies, such as the MRI.
In nuclear astrophysics, state-of-the-art theoretical and computer models help to explain the powerful stellar known as supernovas, to account for how stars shine, and to describe how the chemical in the universe were formed. A Trip into the Heart of Matter tells the story of the nucleus from the early experimental work of the quiet New Zealander Lord Rutherford to the huge atom-smashing machines of today and beyond. Nucleus tells of the protons and neutrons of which the nucleus is made, why some nuclei crumble and are radioactive, and how scientists came up with the "standard model," which shows the nucleus composed of quarks held together by gluons.
It is also the tale of the people behind the struggle to understand this fascinating subject more fully, and of how a research community uses the power of the nucleus to probe unanswered scientific questions others seek to harness the nucleus as a tool of twenty-first-century medicine. Scott Birney, et al.
The long-awaited second edition of this well-received textbook gives a thorough introduction to observational astronomy. Starting with the basics of positional astronomy and systems of time, it continues with charts and catalogs covering both historically important publications and modern electronic databases. The book builds on a fundamental discussion of the basics of light and the effects of the atmosphere on astronomical observations.
Chapters include discussions of optical telescopes, detectors, photometry, variable stars, astrometry, spectroscopy, and solar observations. This edition contains new discussions of measurements with CCDs and appendices give basic statistical methods, useful astronomical software and websites, and sources of accurate time-calibration signals. Examples based on real astronomical data are placed throughout the text. Each of the well-illustrated chapters is supported by a set of graduated problems and suggestions for further reading.
In its 96th year of publication, the Handbook is a concise, high-density compilation of information that is of interest to observers. Each year, some 12, copies are distributed to amateur and professional astronomers, educators, observatories, libraries and planetaria. Since the first edition in , the various editors, assistants and contributors have voluntarily contributed their time and expertise and the Handbook is hence the main source of income for the RASC.
Among the many other updated sections in this edition are: A perennial favorite, the Observer's Handbook gathers the expertise of more than 40 astronomers to detail times of sunrise and sunset, moonrise and moonset, where to find the planets -- major and minor, the movements of the major moons of Jupiter and Saturn, variable star cycles and countless other celestial events. Published since by the Royal Astronomical Society of Canada, the renowned Observer's Handbook is the astronomy hobbyist's standard reference for astronomical data for North America.
The Messier Catalogue is a list of one hundred and ten galaxies, star clusters and nebulae, and includes many of the brightest and best-known objects in the sky. Amateur astronomers who find all the objects on the list in one night have successfully completed the Messier Marathon. The Observing Guide to the Messier Marathon contains over 90 easy-to-use star maps to guide the observer from one object to the next, and provides tips for a successful night of observing.
Don Machholz also tells the story of the eighteenth-century astronomer, Charles Messier, and how he came to compile his extensive catalogue. This complete guide to the Messier Marathon will help the amateur astronomer to observe the Messier Objects throughout the year, using a small telescope or a pair of binoculars. This useful guide for amateur astronomers takes readers on a celestial journey to many of the most prominent stars and constellations visible from mid-northern latitudes. A great first-time reference, this book will help beginning stargazers become familiar with the stars and constellations visible from their backyards through inexpensive, handheld binoculars.
Introducing a range of useful techniques and skills for those wishing to undertake observational work in astronomy and planetary science, this book covers the principles of telescopes and detectors, photometry and spectroscopy and microscopy techniques for analyzing samples. The night sky - positional astronomy; 3. Reducing CCD data; 7.
Microscopes and microscopy techniques; Interpreting images of planetary surfaces; Part II. Preparing for practical work in astronomy and planetary science; Analyzing experimental data; Making use of graphs; Using calculators and computers; Gerald North's complete practical guide and resource package instructs amateur astronomers in observing and monitoring variable stars and other objects of variable brightness.
Descriptions of the objects are accompanied by explanations of the background astrophysics, providing readers with real insight into what they are observing at the telescope. The main instrumental requirements for observing and estimating the brightness of objects by visual means and by CCD photometry are detailed, and there is advice on the selection of equipment. The book contains a CD-ROM packed with resources, including hundreds of light-curves and over printable finder charts.
Containing extensive practical advice, this comprehensive guide is an invaluable resource for amateur astronomers of all levels, from novices to more advanced observers. Joseph Silk On the Shores of the Unknown: Astronomer Joseph Silk explores the Universe from its beginnings to its ultimate fate.
He demonstrates how cosmologists study cosmic fossils and relics from the distant past to construct theories of the birth, evolution and future of the Universe. Stars, galaxies, dark matter and dark energy are described, as successive chapters detail the evolution of the Universe from a fraction of a microsecond after the Big Bang. Silk describes how physicists apply theories of subatomic particles to recreate the first moments of the Big Bang, and how astronomers chart the vast depths of space to glimpse how the most distant galaxies formed. He gives an account of the search for dark matter and the dark energy that will determine the ultimate fate of the Universe.
It shows how one man, Tycho Brahe, used his powerful position to bend the lives of hundreds of others toward a goal that he deemed important: It shows how he established a new role for the astronomer as large-scale organizer, active reformer, and natural philosopher. This pioneering study includes capsule biographies of over a hundred individuals, all of whom helped shape the culture of the Scientific Revolution. Kepler to Werner von Braun, sees in the rise of spaceflight a metaphor of modern history as a recurrent story of transformation and rebirth.
The second recalls the romantic vision of the decades before Sputnik. The third essay looks at the moon landing as the signature event of our century, while the fourth offers new perspectives on the nature of wonder. The final essay returns to the themes of transformation and rebirth. Michael Light Suns: Between July and November the United States is known to have conducted atmospheric and underwater nuclear tests. It became literally invisible—but more frequent: National Archives in Maryland. It includes previously classified material from the clandestine Lookout Mountain Air Force Station based in Hollywood, whose film directors, cameramen, and still photographers were sworn to secrecy.
The title, Suns , refers to the response by J. Robert Oppenheimer to the world's first nuclear explosion in New Mexico when he quoted a passage from the Bhagavad Gita, the classic Vedic text, "If the radiance of a thousand suns were to burst forth at once in the sky, that would be like the splendor of the Mighty One I am become Death, the destroyer of worlds. Featuring glorious photographs, original illustrations and clear prose in a large format, One Universe explores the physical principles of motion, matter and energy that govern the workings of our own world so that we can appreciate how they operate in the cosmos around us.
A comprehensive mathematically detailed textbook on classical celestial mechanics, including numerical methods, astrodynamics of artificial satellites and interplanetary craft. This revised edition involves updates to all chapters and the addition of a new chapter on The Caledonian Symmetrical N-Body Problem, explaining the principles and applications from first principles.
This will be the first time this new method has appeared in a textbook. The contents have been reorganized and extended to encompass new methods and teaching demands and to cover more modern applied. Chondrites are the largest group of meteorites. They can provide unique insights into the origins and early evolution of our solar system, and even into the relationships between our solar system and other stars in the vicinity of our sun.
The largest structural components of most chondrites are the glass-bearing chondrules, and there are numerous theories for their origin. Sears summarizes the ideas surrounding the origin and history of chondrules and chondrites, drawing on research from the various scientific disciplines involved. With citations to every known published paper on the topic and extensive illustrations.
Fred Adams Origins of Existence: In O rigins of Existence astrophysicist Fred Adams takes a radically different approach from the long tradition of biologists and spiritual leaders who have tried to explain how the universe supports the development of life. He argues that life followed naturally from the laws of physics -- which were established as the universe burst into existence at the big bang. Those elegant laws drove the formation of galaxies, stars, and planets -- including some like our Earth. That chain of creation produced all the tiny chemical structures and vast celestial landscapes required for life.
Ultimately, physical laws and the complexity they generate define the kind of biospheres that are possible -- from an Amazon rain forest to a frigid ocean beneath an ice sheet on a Jovian moon. This is a book about the beginning of things—of the universe, matter, stars, and planetary systems, and finally, of life itself. After surveying prescientific accounts of the origins of life, Lurquin examines the concepts of modern physics and cosmology, in particular the two pillars of modern physics, relativity and quantum theory, and how they can be applied to the Big Bang model of the creation of the universe.
The book then considers the role of genetics and DNA and ultimately examines how "protocells" may have started a kind of integrated metabolism and how horizontal gene transfer may have speeded up evolution. Finally, Lurquin examines the possibilities of the end of life and the destruction of the universe, either by nuclear war or natural means. This concise and beautifully illustrated book traces the evolution of the Cosmos from the Big Bang to the development of intelligent life on Earth, conveying clear science in an engaging narrative.
By mapping the history of the Universe for introductory science and astrobiology course for non-science majors, this book explores many of the most fascinating questions in science. What is the origin of the Universe? Why do people search the sky? For many millennia the starry night sky has been a source of wonder and awe to men and women who have tried to unravel the mystery of the billion distant lights that fill the heavens after dark.
The story of the great discoverers who succeeded in explaining part of the mystery is told here with the joy and infectious enthusiasm that only a fellow discoverer can convey. David Levy, codiscoverer of Comet Shoemaker-Levy 9 and ASP Board member, with his wife, Wendee Wallach-Levy, gives a glimpse of the enthralling adventure of cosmic discovery through stories of the most famous and brilliant astronomers. For example, Galileo's breathtaking discovery of the moons of Jupiter, new worlds that refused to orbit the sun, challenged the whole doctrine of the earth being the center of the universe.
With the start of the 20th century, Shapley pushed back the envelope that had been opened by Galileo by proving that the center of our galaxy is very far beyond our own sun. And Hubble showed that even our galaxy is but a tiny part of a universe that is rapidly expanding.
Beyond their personal accomplishments, these scientists expanded all of humanity's understanding of the universe and our place within it. Eric Chaisson Cosmic Evolution: Now emerging is a unified scenario of the cosmos, including ourselves as sentient beings, based on the time-honored concept of change. From galaxies to snowflakes, from stars and planets to life itself, we are beginning to identify an underlying, ubiquitous pattern penetrating the fabric of all the natural sciences — a sweepingly encompassing view of the order and structure of every known class of object is our richly endowed Universe.
We call this subject "cosmic evolution. Guided by notions of beauty and, by the search for simplicity and elegance, by the ambition to explain the widest range of phenomena with the fewest possible principles, Chaisson designs for us an expansive yet intricate model depicting the origin and evolution of all material structures. He shows us that neither new science nor appeals to nonscience are needed to understand the impressive hierarchy of the cosmic evolutionary story, from quark to quasar, from microbe to mind.
Supernovae and gamma-ray bursts are the strongest explosions in the universe. Recent observations have shown that rather than being symmetrical, they are driven by strong jets of energy and other asymmetrical effects that reveal previously unknown physical properties. These observations have demanded new theories and computations that challenge the biggest computers. This volume marks the transition to a new paradigm in the study of stellar explosions. It highlights the burgeoning era of routine supernova polarimetry and the new insights into core collapse and thermonuclear explosions.
Leonard Susskind The Cosmic Landscape: The beginning of the 21st century is a watershed in modern science, a time that will forever change our understanding of the universe, Leonard Susskind contends. Several decades ago, Susskind introduced the revolutionary concept of string theory to the world of physical science.
In doing so, he inspired a generation of physicists who believed that the theory would uniquely predict the properties of our universe. This book is devoted to the cosmological implications of the gauge theories of particle physics and of string theory. It presumes some prior knowledge of these subjects, such as that provided in the authors' previous books Introduction to Gauge Field Theory and Supersymmetric Gauge Field Theory and String Theory , but it is self-contained.
As it cooled after the hot big bang, it is likely that the universe passed through a series of phase transitions in which the successive gauge symmetries of the higher-temperature phase were spontaneously broken. The survival to the present of relics of these phase transitions is discussed, as is that of more generic relics baryons, neutrinos, axions and supersymmetric particles neutralinos and gravitinos.
Recent observations confirm that the universe is very flat and extremely homogeneous. The most plausible explanation of this is that the universe passed through an inflationary era. The constraints on the presumed underlying field theory are studied and the possibility of satisfying these in a supersymmetric theory or in supergravity theory is discussed. Finally, black hole solutions of the supergravity theory that approximates string theory at low energies are considered, and the insight that string theory affords into the microscopic origin of the Bekenstein—Hawking entropy is discussed.
Cosmology in Gauge Field Theory and String Theory will provide a modern introduction to these important problems from a particle physicist's perspective. A dramatic photographic tour of the universe. The observable universe contains some hundred billion galaxies—each one made up of as many stars. Of the vast billions of stars, only a scant 5, are actually visible from Earth with the naked eye.
Over the last twenty years, space probes and space-based telescopes have released us from the confines of Earth and catapulted us into the open reaches of space to capture worlds beyond our own. Cosmos showcases magnificent celestial objects of unparalleled beauty, gathering the most dramatic images of the night sky—from close planets and our sun to the most remote galaxies. Organized into the following chapters: Alan Boss The Crowded Universe: In The Crowded Universe , renowned astronomer Alan Boss argues that based on what we already know about planetary systems, in the coming years we will find abundant Earths, including many that are indisputably alive.
Life is not only possible elsewhere in the universe, Boss argues -- it is common. Boss describes how our ideas about planetary formation have changed radically in the past decade and brings readers up to date on discoveries of bizarre inhabitants of various solar systems, including our own. America must stay in this new space race, Boss contends, or risk being left out of one of the most profoundly important discoveries of all time: What are the current ideas describing the largescale structure of the universe?
How do they relate to the observed facts? This book looks at both the strengths and weaknesses of the current big bang model in explaining certain puzzling data. It arises from an international conference held at the College de France, Paris in June , which brought together many of the world's leading players in cosmology. In addition to presenting individual talks, the proceedings of the resulting discussions are also recorded. LoPresto has taught introductory astronomy at Henry Ford CC since and found that traditional textbooks "list the steps of the scientific method like cookbook instructions then gloss over the sky's motions and history on the way to 'more important' material Cycles is designed to stand alone as a more in-depth look at the motions in the sky We wish to understand why the night sky is dark and the nature of the dark matter in the universe.
These topics are intimately related.
Similar authors to follow
The darkness of the night sky is due to the age of the universe, its rate of expansion and its content of luminous matter in the form of stars and galaxies. However, the latter have motions, which imply the existence of large amounts of non-luminous material, probably in the form of particles. These slowly decay, producing photons. So while intergalactic space is dark, it is not completely black. Understanding the relation between the dark sky and dark matter is comparable to a modern version of Olber's paradox.
The approach of the authors is to compare the best observational data from large telescopes with the best cosmological theory based on general relativity and particle physics. This gives us a more accurate picture of the universe and the exotic material believed to constitute dark matter. The dark night sky; The modern resolution and energy; The modern resolution spectra; The dark matter; The vacuum; Axions; Neutrinos; Supersymmetric weakly interacting particles; Black holes; Conclusions; Appendices: Bolometric intensity integrals; Dynamics with a decaying vacuum; Absorption by galactic hydrogen.
This timely volume presents specially written articles by world experts at an international conference at the Space Telescope Science Institute. The goal of the meeting was to assemble physicists and astronomers working on all aspects of dark matter and theories of gravity. David Levy has held a lifelong passion for comets, and is one of the most successful comet discoverers in history. In this book he describes the observing techniques that have been developed over the years - from visual observations and searching, to photography, through to electronic charge-coupled devices CCDs.
He combines the history of comet hunting with the latest techniques, showing how our understanding of comets has evolved over time. This practical handbook is suitable for amateur astronomers, from those who are casually interested in comets and how to observe them, to those who want to begin and expand an observing program of their own.
Drawing widely from his own extensive experience, Levy describes how enthusiastic amateurs can observe comets and try to make new discoveries themselves. More than a decade ago, David Levy, award-winning astronomer and Society board member, wrote The Sky: Fully updated, the new edition includes: A new section on the computer-controlled telescopes and how to use this new technology; one new chapter on how charge-coupled devices CCDs have revolutionized the art of astronomical observation; an explanation of how a new variable star is discovered and studied, based on Levy's personal experience.
Levy explores topics as diverse as the features of the Moon from night to night; how to observe constellations from both urban and rural observation sites; how best to view the stars, nebulae, and galaxies; how to find a new comet; how to buy or even make a telescope; what to see in a month of lunar observations or a year of stellar observations; and how to map the sky.
Found throughout the universe, variable stars are fascinating objects to observe. Their brightness changes over time and they can easily be seen with even the most basic equipment. ASP Board of Directors member David Levy explains how to begin electronic or CCD observing, as well as how to observe variable stars through a small telescope or binoculars.
Featuring a section on Southern hemisphere stars, this book covers various types of objects that can be observed by amateur astronomers, including more exotic phenomena like gamma ray bursts, blazars, and polars. For millions of years, human anatomy and human behavior evolved together. But only 50, years ago, anatomical evolution came to a near halt while behavioral evolution accelerated dramatically. This important shift became the dawn of what we now consider modern behavior and was the starting point of human culture. What sparked this incredible revolution is truly the greatest mystery of human evolution.
Preeminent anthropologist Richard G. Klein reexamines the archaeological evidence and introduces the latest information on the study of the human brain and human genetics to present an absorbing account of the correlation between brain development and the earliest known origins of human consciousness. Jansky identified static from thunderstorms and random radio noise from devices on Earth, but he also found a radio hiss from the Milky Way galaxy.
After World War II, astronomers constructed more radio telescopes with greater sensitivity to faint radio signals from space.
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The VLA is well equipped to hunt for strange objects and solve astronomical mysteries. The VLA receives radio signals from outer space. Most are so faint, a blastingly strong signal would be a cell phone ringing on the moon, , miles away from Earth. The VLA has shown ice on the burning-hot planet of Mercury, has discovered a burst of brand-new star formations, and has probed dying and exploding stars. Karen Taschek introduces young readers to the wonders revealed by the VLA.
She begins with basic information on our solar system and our own Milky Way galaxy and then extends the discussion to galaxies billions of light-years from Earth. William Dembski, Michael Ruse, and other prominent philosophers provide a comprehensive balanced overview of the debate concerning biological origins—a controversial dialectic since Darwin published The Origin of Species in Invariably, the source of controversy has been "design. Or, does the appearance of design signify genuine prevision and teleology, and, if so, is that design empirically detectable and thus open to scientific inquiry?
Four main positions have emerged in response to these questions: Darwinism, self-organization, theistic evolution, intelligent design. The contributors to this volume define their respective positions in an accessible style, inviting readers to draw their own conclusions. Two introductory essays furnish a historical overview of the debate. There is no doubt that the Hubble Space Telescope HST in its first decade of operation has had a profound impact on astronomical research.
But HST did much more than that. It literally brought a glimpse of the wonders of the universe into millions of homes worldwide, thereby inspiring an unprecedented public curiosity and interest in science. Unlike astronomical experiments that were dedicated to a single, very specific goal, HST's achievements are generally not of the type of singular discoveries.
More often, HST has taken what were existing hints and suspicious from ground-based observatories and has turned them into certainty. In other cases, the level of detail that HST has provided forced theorists to re-think previous broad-brush models, and to construct new ones that would be consistent with the superior emerging data. In a few instances, the availability of HST's razor-sharp vision at critical events provided unique insights into individual phenomena. These proceedings represent a part of the invited talks that were presented at the symposium, in order of presentation.
Stephen O'Meara's new and exciting observing guide spotlights an original selection of deep-sky objects that will appeal to sky-watchers worldwide. His 'hidden treasures' include a wonderful assortment of galaxies, open clusters, planetary nebulae and more, all of which have been carefully chosen based on their popularity and ease of observing.
None of these objects are included in either the Messier or the Caldwell catalogs, and all are visible in a 4-inch telescope under dark skies. Stunning photographs and beautiful drawings accompany detailed visual descriptions of the objects, which include their rich histories and astrophysical significance. The author's original finder charts are designed to help observers get to their targets fast and efficiently. For more than two centuries, amateur astronomers have earned their stripes by observing the star clusters, nebulae, and cataloged by French comet hunter Charles Messier.
Sir Moore has compiled a new list of deep-sky delights, the Caldwell Catalog, which covers the entire celestial sphere. Stephen James O'Meara has observed all Caldwell objects and Deep Sky Companions presents his beautiful sketches and detailed visual descriptions and discusses each object's rich history and astrophysical significance. The latest fundamental data on each object are tabulated, and the book's star charts will lead observers to each object's precise location.
David Levy Deep Sky Objects: As the discoverer or co-discoverer of twenty-one comets, including Shoemaker-Levy 9 that crashed into Jupiter in, David Levy has devoted many decades of experience to observing the night sky. Light years beyond our solar system, deep sky objects include such intriguing phenomena as double and triple stars, nebulae, galaxies, and quasars. Complete with both color and black-and-white photos, plus many helpful illustrations.
From galaxies to globular and open clusters, from nebulae to double stars, the Deep Sky Observer's Guide introduces the basics of observing and explains what equipment is required. To view most of the objects described, binoculars and small telescopes are explained, along with accessories such as filters and mounts.
Also includes descriptions of challenging deep sky objects and of the hardware with more powerful magnification necessary to view them. Mark Wolverton The Depths of Space: The first spacecraft to explore the secrets of the Sun, Jupiter, Saturn, and the void beyond Pluto, the Pioneer space probes have been the trailblazers of the space age, truly going where no man has gone before. Emblazoned with the nude figures of a man and a woman, etched representations of our human form, the Pioneer generation of probes were aptly named. Launched into the inky depths of space, they were more than mere machines, they were humanity's first emissaries into deep space.
And the pictorial inscriptions that adorned the crafts embodied the hopes and dreams of everyone involved in the Pioneer program Perhaps the most efficient, reliable, and cost effective program to come out of NASA, the Pioneer missions are a shining example of how a small and talented group of people can, against all odds, pull something off that has never been done before. Indeed, more than thirty years after its launch in , Pioneer 10 is still cruising into interstellar space, sending back data as it courses through the galaxy while Pioneer 6, in solar orbit, is more than 35 years old and humankind's oldest functioning spacecraft.
But despite their enduring contributions, the Pioneer project remains a footnote in space history, little more than a humble prologue to its inheritors. The Depths of Space recounts the long overdue history of Pioneer both as a scientific and technological achievement and as the story of the exceptional people who made the program possible. This tight narrative captures the black-coffee buzz of full-throttle, deadline-driven production, the sharp, intense thrill of discovery, the pang of anxiety that accompanies looming danger and ultimate loss, and the satisfaction and pride of creating an enduring legacy.
Destination Mars begins with the earliest references to Mars in the mythology of ancient civilizations in Mesopotamia, Babylon, Egypt, Greece and Rome, then discusses the origins of the scientific revolution brought about by men like Newton, Kepler, Huygens and Galileo. After pausing for a quick look at Mars in literature and the movies, author Dupas moves to the development of rockets, the saga of space exploration and the search for life on Mars, including "The Extraordinary Revelations of Mariner 9," immense volcanoes, dry river beds, and gigantic canyons.
The successes and failures of more recent craft are covered, as well as a section on astronauts and the future of humans in space. Finally, coupling the science of today with the best available theories about tomorrow, Destination Mars reports on future explorations as if they have already occurred. Includes never-before-seen photos, some of them in fold out three-and four-page spreads and evocative illustrations by Ron Miller.
Award-winning science writer Seymour Simon has teamed up with the Smithsonian Institution for new updated editions of his acclaimed long running series of photo-essays. Matching full-color, full- and double-page-spread-sized light and radio photographs of nebulas, galaxies, and sundry deep-space phenomena with two or three paragraphs of explanatory text. This revised edition contains 4, up-to-date entries written by an expert team of contributors, under the editorship of Ian Ridpath. Covering the most recent space exploration missions and latest technological development, this authoritative dictionary covers everything from astrophysics to galaxies and time.
World-wide coverage of observatories and telescopes, and major entries on supernova, Big Bang theory, and stellar evolution. In the absence of evidence, it's often wiser not to speculate.
When creating theories or distinguishing between competing theories, scientists rely on two distinct types of reasoning: Inductive reasoning works from the specific to general. It involves making observations and building generalizations on the basis of observations. For instance, you might observe the sunrise every day for a year, and you notice that this Sun rises more or less in the east every time.
You might conclude that the Sun always rises in the east. Inductive reasoning involves drawing conclusions from a limited sample of information. You have no way of knowing that the Sun won't rise in the west tomorrow.
Still, a pattern will become apparent as observation continues, and year after year of observation makes it compelling to imagine that the Sun must always rise in the east. If the pattern remains very consistent, it can be considered reliable even if the underlying cause isn't obvious. Should a theory ever be presented that predicts that the Sun will always rise in the east, that theory will be well supported. On the other hand, if a theory predicts that the Sun will sometimes rise in the east and sometimes in the west, that theory will be disfavored by the observations even though it isn't disproved in a strict sense.
Notice that it is possible, though unlikely, for inductive reasoning to discredit a correct theory or support an incorrect theory. Although it is a powerful and essential tool in science, inductive reasoning must be treated with skepticism when based on a very limited sample of observations. Deductive reasoning works from the general to the specific. It is based on logical arguments syllogisms. An example of deductions invented by the author Lewis Carroll is provided below:.
Unlike inductive reasoning, deductive reasoning is perfectly reliable if you have made correct assumptions and applied correct logic. Because deductive reasoning is absolutely reliable when used with good assumptions and proper method, it is easy to place undue trust in claims made on the basis of deductive reasoning.
It is important to remember that these claims also require careful examination to check that the assumptions are good and the reasoning is valid. In reality, deductive reasoning is as much subject to error as inductive reasoning. Only the sources of error differ. Astronomy like all sciences is a social activity in which people are constantly discussing new ideas, interpreting data, and arguing with each other over what observations mean.
Astronomers can broadly be divided into two groups. Observational astronomers specialize in building instruments such as telescopes, and spacecraft, and take raw data and process them into meaningful results. Theoretical astronomers often also known as astrophysicists take the results that observational astronomers provide and attempt to create physical models which explain the data that observers see and provide ideas of the directions that observers should go into.
Theoretical astronomers increasingly rely on computer models and often are skilled at programming. Astronomy is rather unique in that a lot of the data is provided by amateur astronomers. The data needed in some fields such as variable star astronomy or comet discovery can be gathered by instruments well within the budget of an interested hobbyist. A central part of the scientific process is peer review which occurs at several stages in the process, and creates what H. Bauer calls a knowledge filter. In the peer review process, a proposal or a journal article is given to a group of referees who anonymously submit their comments on the proposal.
While the referees will sometimes communicate with each other, they are not intended to reach a consensus on the quality of work. In addition, the referees usually do not have the final authority to decide on the fate of a proposal, but instead given their opinions to an editor or project director who does have the final authority and on occasion overrides the opinions of the referees. The opinions of the referees are usually made available to the submitter, and often contain suggestions for improvement to the submitter. This is considered crucial for the scientific process as it allows the submitter to receive feedback on his or her proposal and improve it.
In some cases, the submitter is encouraged to resubmit their proposal after making changes, and this often develops into an anonymous communication between the referees and the submitter. In order to get these resources, astronomers typically write grant proposals which outline the amount of money, telescope, and computer time needed. Grant proposals typically undergo peer review by the granting agency which includes feedback on how well it fits the priorities of the funding agency, how likely the committees think it is to advance the frontiers of knowledge, and how essential the resource being allocated is to the researcher.
Typically, a set portion of telescope or supercomputer time will be made available to the institution that hosts or funds the resource, giving scientists affiliated with that institution priority use over that resource. The remaining time is then made open for research proposals from researchers from other institutions. In the case of ground based telescope time, the most precious and highly sought after time is dark time during which the moon is new and the dimmest objects can be seen. In some cases, such as building a new telescope, supercomputer center, or funding a new spacecraft, astronomers must lobby funders such as charitable foundations and legislators for money to finance a certain activity.
The lobbying for research facilities can be extremely intense as having a facility sited at your institution gives your institution priority access to the facility, as well as prestige, and makes your institution a destination for researchers. Typically, in an observing run, you wake up at about 3 p.
During the day the technicians will have installed the instruments that you need for a nights observing run. You go to the telescope at 3 p. After the sun starts setting, your first goal is to find the object that you are trying to photograph. You can punch in the coordinates into the computer, but that will only point the telescope in the general area of the sky that you are interested in.
The next thing that you have to do is to take out your star atlas, and look for a pattern of stars that is close to the thing that you are looking for. This is a lot like driving in a strange city when you are looking at the monitor and then trying to match the patterns you see with the patterns on the chart. So you've now found the object you are looking for. In between these measurements, you take some snapshots of a calibration device. If you are looking at spectra, you take picture of a fluorescent lamp that has lines in certain known positions. If you are measuring brightness, then you need to take some pictures of a star whose brightness is known.
So after a night of all of this, you now have some data on hard disk, and you go to sleep. The next few weeks is where the hard part comes in. You see you have a lot of raw data, but it's not very useful to anyone. The problem is that none of the data has been calibrated. So you spend the next few weeks taking the data, subtracting the black levels, correcting the white levels, stretching and shrinking the picture so that you know what the frequencies of your spectra are. You might also be spending your time doing things like trying to correct for the effects of dust in the galaxy.
Through it all, you are probably using an astronomy package called IRAF, which like all big software packages has its cute bugs and idiosyncrasies. At the end of all of this you have a paper, and are ready to publish. Observational astronomers are often at the mercy of things that are outside of their control. Weeks if not months of effort at setting up an observing run can be destroyed if it happens to be cloudy or raining on the night of the run. Unlike observers, theorists are creatures of the day. The typical theorist spends their days reading papers trying to understand how to model a particular type of phenomenon.
Once they have a model, the goal then is to try to get testable predictions from that model, and this often means programming a computer to calculate the consequences of that model. There are occasional flashes of inspiration, but most of the time is spent very slowly and methodically trying to understand the consequences of a model, and to slowly and methodically program the model into a computer and systematically remove the bugs from the model.
There are also a lot of social interactions as theorists argue and debate what a particular observation means, and as theorists and observationalists share ideas about the latest data. There are a number of channels through which scientific results are made known. The primary means that astronomers use to make others aware of current research are through preprints which are papers uploaded through web servers such as the Los Alamos Preprint Server at http: Astronomers are also constantly travelling between departments to give talks on their research at seminars, astronomy lunches, and journal clubs.
Although it has been supplemented by preprints, peer reviewed publication in the primary literature is still considered an essential part of publicizing research. This literature consists of articles in journal such as Astrophysical Journal or Astronomy and Astrophysics. Because of the length of time, typically several months, necessary to go through a peer review, research results are typically shared with the community through preprints before peer review is complete. Nevertheless, astronomers still generally submit their papers to peer review even after the results have been released to the research community, because the interaction between anonymous referees and the paper submitter improves the quality of the work and insures the community that the paper does not have any obvious errors.
Once an astronomy paper is available for publication, it can be accessed through the Astrophysics Data System at http: One shortcoming of the primary literature is that it reports on individual research results without providing context. As such it is difficult for someone who is not actively involved in research in a particular area to understand the relevance of the work. To deal with this problem, primary literature is summarized and combined into the secondary literature , where it will be read by a broader audience of scientists.
The secondary literature is a synthesis of the results of recent research in a field. Most astronomers major in either physics or astronomy as an undergraduate and then go to graduate school where they work on the Ph. The main challenges in becoming an astronomer are to master the language of mathematics and physics, and to gain experience in working through the scientific process. After graduate school, an astronomer typically works as a post-doctoral fellow before getting a job either as a professor at a university or a researcher at a laboratory. Because of the large number of graduates gaining Ph.
They work in science related fields, as computer programmers for software companies and even on Wall Street. Astronomy also is open for amateur astronomers. Most of the data for variable stars is accessible via a telescope which is affordable by hobbyists, and amateurs provide important observational data.
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When a result is believed likely to be controversial such as the possible discovery of microfossils on Mars , the researchers may choose to keep the finding secret until peer review is complete so that the result will likely withstand challenges after it is released. Another case where results are kept until peer review is complete involves releasing large datasets such as sky surveys.
In this case, the delay introduced by peer review is small in comparison to the benefits of having a through review before announcing the results. How is the paper structured and what concepts in this text book do you find in the papers? What is being discussed? How are different astronomy departments different from each other and how are they the same? Dark matter is invisible, but has been postulated from its apparent influence on visible matter. It is one explanation for the observed strength of gravity needed to hold galaxies and clusters of galaxies together.
Without considerably more mass than can be detected with telescopes, roughly 10 times more, these systems should simply fly apart. The dark matter theory hypothesizes that matter exists that emits little or no radiation and therefore is not observable with telescopes. Dark matter might also be needed to explain the cosmic microwave background CMB power spectrum. Another hypothesis, dark energy, has been proposed to explain the surprising observation that the expansion of the universe is getting faster. This acceleration of the expansion was discovered by measuring a certain type of supernova, called type Ia, in surveys of galaxies.
Type Ia supernova are used since they all have the same absolute brightness. This makes them very useful for measuring distances. It had been anticipated, before the measurements were made, that the expansion of the universe would be decelerating, due to the gravity of all the matter. Dark energy is postulated to explain the apparent repulsive force pushing things apart.
Ongoing research efforts are to measure the expansion rate more accurately, and discover the nature of dark energy. Dark matter is generally accepted to exist, though questions remain. It is probably not regular matter made of protons and neutrons baryonic matter. That is because a higher density of ordinary matter during the nuclear reactions occurring in the first few minutes of the universe known as big bang nucleosynthesis , would be expected to produce different abundances of light elements and their isotopes, like deuterium, than are actually observed.
Another problem for ordinary matter is that the "clumpiness" of the observed galaxies and the cosmic background radiation is not what would be expected from predictions. Other considerations tend to disfavor neutrinos as dark matter as well. Alternatives to the dark matter hypothesis are new forces or modified gravity theories. There is speculation that there is another large-scale force that is keeping our universe together.
If you place two objects apart from each other then pressurize the area, the two objects will be forced towards each other. This reverses our current ideas of gravity from an object having a pull on other object, to an object being pushed from all directions. An object alone has no movement, but two objects create an uneven pressure pushing the objects together. The most popular theory right now is that the repulsive force is actually a property of space itself: Early in the universe, when there was not much space, the effect was small compared to gravity.
But as the galaxies moved apart, the effect became greater. Dark matter was first proposed in by Swiss astrophysicist Fritz Zwicky to explain the orbital motions of galaxies in clusters. He observed that there was apparently much more mass in a cluster of galaxies than just the visible objects, like stars, gas, and dust. So there was something unseen adding to the mass of the cluster. Later, when X-ray telescopes became operational, they revealed a cloud of hot hydrogen gas between the galaxies, accounting for part of the missing mass.
Beginning in the 's, Vera Rubin discovered that contrary to Kepler's law that objects orbiting around a central body move slower the farther away they are, that in fact the orbital speed of stars in galaxies remains roughly the same beyond a certain distance from the galaxy core. So there has to be some extra matter, either in the flat disk of galaxies or in a spherical halo around the galactic core.
The term dark matter refers to matter that is perceived to be present because of its effect on the objects around it. While the composition of dark matter is still unknown, scientist have proposed some possible candidates that dark matter could be. A more in-depth flow chart depicting how the above suggestions are connected is picture below taken from Modern Cosmological Observations And Problems The cosmic background radiation was formed when protons and electrons combined to form atoms.
The trouble is that we know that the matter between galaxies today is ionized i. We know this because when we look at all but the most distant galaxies, we don't see the spectra lines of hydrogen. So at some point the hydrogen in the universe reionized. The notion was that starlight caused the hydrogen in the universe to reionize, but the latest observations seem to indicate that this reionization occurred before the first stars were there.
The idea is that galaxies started from tiny fluctuations in density that formed after the big bang. By assuming that the universe consists mainly of cold dark matter, you can almost get the clumpiness that you see with the current galaxies. But there are still puzzles. There is an annoying lack of tiny galaxies, and the rotation curve that cold dark matter predicts, isn't quite the one that we see.
Now to get really speculative, there have been some papers written recently that try to figure out what happened before the Big Bang. One of the strange ideas is that the universe is merely one plane in a multidimensional space, and that what happened was that two membranes in a multidimensional space collided causing a massive expansion in three of the dimensions. This is all really speculative, but the weird thing is that it isn't totally disconnected from observation. The idea is that you can use this model to predict the initial expansion of the universe, and this might have some effects on the ripples that you see in the cosmic microwave background.
The big problem is that the matter that began expanding had to have always existed, yet, because of the predictable nature of the elements, it had to have had a definite, external force to set it in motion that could decide when to start the "chain reaction". Something cannot just be in a stable form, or even an unstable form, forever and finally explode, it has to go in a cycle. In other words, consider the following. Out of nothing, a theretofore nonexistent dense mass spontaneously emerged, which erupted in an enormously powerful fireball by its own theretofore nonexistent energy to spontaneously and immediately create from this chaos the defined fundamental forces of physics and the subatomic fundamental particles, which eventually organized themselves into a variety of atomic species, then into molecules, and then into a diverse assortment of inorganic matter that gravitationally assembled itself into this highly structured and precisely ordered universe.
We all know that this is ridiculous, but it is equally ridiculous to say "a theretofore stable mass spontaneously became unstable". With all of these puzzles, its not clear what is going to happen next. There is a lot of data coming in, and it may be that with new data, it will be possible to make our models of the universe work with minor tweaks here and there, and we can go on in the mode of what Kuhn calls "normal science. What mysteries in the old astronomy textbook are now believed to be resolved, and what facts and statements in the old astronomy textbook are now believed to be incorrect?
If you look out from an empty field into a dark sky, you will get the impression that you are standing on a flat plate, enclosed by a giant dome. Depth perception fails us for the distant objects we see in the sky. This creates the appearance that all of the stars have the same distance. The stars appear to move together across the sky during the night, rising in the east and setting in the west, as if they are affixed to the inside of a dome.
Because of this, many ancient civilizations believed that a dome really did enclose the Earth. Only a few centuries ago astronomers came to realize that the stars are actually very far away, scattered throughout the Milky Way Galaxy, rather than attached to the inside of a vast sphere. The old idea remains useful, however. The concept of the celestial sphere provides a simple way of thinking about the appearance of the stars from Earth without the complication of a more realistic model of the universe.
Working with the celestial sphere offers a convenient way of describing what we see from Earth. When we refer to the celestial sphere, we are imagining that everything we see on the sky is set on the inside of a huge spherical shell that surrounds the Earth. We will use the reference points of the celestial sphere as the basis for several coordinate systems used to place celestial locations with respect to one another and to us. The celestial sphere is an imaginary hollow globe that encloses the Earth.
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The sphere has no defined size. It can be taken to be infinite or at least really big , with an infinitesimal Earth at the center. The observer is always taken to be at the center of the celestial sphere, even though the observer isn't at the center of the Earth. Our particular position among the stars gives us a particular view. Brighter stars appear closer; stars in nearly the same direction appear nearby each other, even if they are separated by great distances. Our first and most basic look out into the universe is completely stripped of any depth perception. The celestial sphere can be seen from either of two perspectives.
In one perspective, the celestial sphere itself remains still while the Earth turns inside it. In the other perspective, the Earth stands still and the celestial sphere rotates once per day. To an observer on Earth, these two perspectives appear the same. As we think about how we would expect to perceive the rotation of the Earth, we can use this second perspective to guide us.
Everything we see in the sky, we see as though projected onto the celestial sphere. The stars in the constellation Orion, for example, are at a variety of distances, but the differences are imperceptible to us on Earth. Orion's pattern would disappear if we could view it from any other angle or if we could perceive the depth, because the stars would project differently. Because depth perception is lost, measurements of size are much more difficult. The Sun and the Moon look about the same size in the sky, even though the Sun is really much larger. The Sun appears to be the same size as the moon because the Sun is much farther away simply because the Sun is both times larger in diameter and times farther away than the Moon.
Although we can't easily measure the physical sizes of celestial objects, we can measure their apparent sizes. We do this by measuring the angle an object subtends in the sky. The Sun and the Moon, for example, subtend an angular diameter of half a degree. Most objects in the sky are smaller than this, so it is often convenient to use a smaller measure of angle. For this purpose, astronomers use arc minutes and arc seconds. There are sixty arc minutes in a degree, and sixty arc seconds in an arc minute. Angles this small are near or beyond the limits of ordinary human vision, but they become useful when using a telescope to make observations.
For casual stargazing, observers think about much larger angles. You can easily measure these angles when stargazing by using your hand as your ruler. This can be useful for estimating the position of a star in the sky, or for gauging the angular separation of two stars. While the apparent movement of a star across the sky each night, with the celestial sphere, is great, the measurement of an object's movement across the Celestial Sphere as the object drifts through space, is called proper motion , and is measured in arc seconds per year. To begin thinking about the view of the sky from Earth, we will identify a few points of reference that are fixed to the ground and of importance to astronomers.
Some of these are widely known from common experience. To any observer, regardless of location, these markers stay in the same positions relative to the observer. The zenith is always directly overhead, the horizon is always level, and so on. Observers standing at different places on Earth will have a different view of the sky. An observer in Singapore might see the Sun at the zenith while another observer in New York would not see the Sun at all.
These reference points change with the location of the observer. There are also reference points that are fixed in the sky. These fixed reference points don't move with respect to the stars, but different observers see them in different positions. They are the basis for the fixed coordinate systems that we discuss later. For now, we will identify only the two most useful of these — the celestial poles and the celestial equator.
The celestial equator is an extension of the Earth's equator onto the celestial sphere. If you stand on Earth's equator, the celestial equator will always be directly overhead and pass through the zenith. It will run from the East point up to the zenith and down again to the West point. Anywhere you stand on Earth, the celestial equator will intersect the East and West points on the horizon.
The nearer you are to the equator, the nearer the celestial equator come to the zenith. At the North Pole or the South Pole, the celestial equator lines up with the horizon. Like the celestial equator, the celestial poles are an extension of the Earth's pole onto the celestial sphere. At the equator, the North Celestial and South Celestial Poles would lie on the horizon where the meridian intersects the horizon.
Polaris is called the "North Star. The last two stars of the "cup" of the Big Dipper are called the Guardians or "Pointers" , and point to Polaris in the sky. Polaris is special because the Earth's North Pole points almost exactly towards it. This means that Polaris will always appear to be due north to any observer, and it will always stay in the same position on the sky. Often, beginning stargazers assume that Polaris must be a very bright or prominent star. This is not really the case. Polaris is only remarkable because it is almost exactly in line with Earth's axis of rotation.
Because of this, Polaris always remains at nearly the same place in the sky. For example, Shakespeare made reference to Polaris in the play Julius Caesar:. Though it must be pointed out that Shakespeare actually got it wrong. At the time Shakespeare wrote Julius Caesar Polaris was indeed the pole star but in Julius Ceasar's time Polaris was not the pole star. The fact that Polaris always stays in the same position due north has given it much fame. It also makes Polaris a useful reference point for navigation — Using geometry, it is easy to show that the angle Polaris or the celestial pole makes with the horizon is equal to the observer's latitude.
The pole and the equator are at right angles, so. This fact was once used by navigators at sea, who could easily find their latitude by measuring the position of Polaris. Like many things in astronomy, the celestial sphere can be very difficult to visualize because of its three dimensional geometry. A visit to a planetarium or a session under the night sky can be very helpful to you in developing a conceptual understanding of the celestial sphere.
In the absence of the opportunity for these, it can be helpful to try to draw diagrams such as the one at the beginning of this section for yourself. To begin drawing a celestial sphere such as the one above, you only need to know the latitude of the observer. Then imagine that the spot where the observer is standing is the "top of the world"; draw circle for the earth, and draw an observer standing at the top. Now draw a much larger circle around that; this represents the celestial sphere.
Since our observer is always on top of the Earth, the features on the celestial sphere that are defined relative to the ground will always be in the same position on the sphere. The zenith is the point directly above the observer's head, at the top of the celestial sphere. The next important reference is the horizon.
The horizon will be horizontal on the diagram. Remember that the celestial sphere has no specific size relative to the Earth, regardless of how you've drawn it. Draw the horizon across the middle of the celestial sphere, so that it's center is the same as the center of Earth. Markers such as the horizon are always idealized, so it doesn't matter whether your observer's view of the sky is actually cut off at the position marked by the horizon.
Think about what the orientation of the pole should be given the observer's latitude. If the observer is at the equator, the pole should go horizontally through the Earth. If the observer is at one of the poles, the pole should go through the Earth vertically. Extend the Earth's poles out to the celestial sphere and mark the intersections as the North Celestial Pole and the South Celestial Pole.
If we're in the northern hemisphere, the North Celestial Pole will be above the northernmost point on the horizon, and the South Celestial Pole will be on the opposite side of the celestial sphere, below the horizon. If we're in the southern hemisphere, the situation is reversed. Remember to check that the angle the horizon makes with the pole is about the same as the observer's latitude. For any given latitude, one can build an appropriate celestial sphere. First, consider the sky in relation to the earth. Take the north and south poles and extend them into the sky; these become the north and south celestial poles.
The Earth's equator can be projected outward to form the celestial equator. We'll get something that looks like the picture above. When you're done, you should have a celestial sphere very like the one at the top of this section. A celestial sphere forms the basis for the application of many coordinate systems.
For example, the horizon and the celestial meridian together form the reference circles for giving the position of stars in terms of altitude and azimuth, making it easier for one to find them on the night sky. The celestial sphere is also a natural system for describing the motion of the sun. In order to explore these concepts, however, it is necessary to understand just how the celestial sphere changes for an observer at a given latitude. As we consider the daily rotation of the Earth, we'll see that your perception of the daily motion depends very much on your latitude.
As you look at the sky, your mind will naturally identify obvious patterns. The Big Dipper and Orion are two very prominent groupings of stars, and others stand out all over the celestial sphere. These asterisms are guideposts to the night sky. You can use them to keep your bearings when you look at the sky. The appearance of the night sky has remained much the same for millennia. Many of the ancient civilizations across the globe invented stories about the sky. Often, the groups of stars are called constellations. Constellations have a very long history in astronomy, dating back thousands of years.
Early in the twentieth century, a list of constellations was formally established by the International Astronomical Union, a widely recognized body of astronomers. The IAU identified constellations that would be used in astronomy and defined specific boundaries to unambiguously establish which constellations each star belonged to. It's easy to learn a few of the most prominent constellations so that you can find your way around the night sky. Beginning with a few easy-to-find landmarks you can find the rest by using familiar stars as guideposts. Another useful guide in the sky is the ecliptic.
The ecliptic is an imaginary line in the sky that the sun draws. The ecliptic is even with the plane of the Earth's orbit around the sun; thus, all of the main planets and the moon should be found relatively close or on the ecliptic, because the solar system is mostly flat.
Also, along the ecliptic are the 12 constellations of the zodiac. Thus, by finding some of the main zodiac constellations in the night sky, one can determine if certain objects they see may or may not be planets by whether or not they lie on the ecliptic. Like the stars and planets, the Moon doesn't stay fixed in the sky but slowly moves as the Earth rotates and as the Moon moves through its orbit about the Earth.
To someone taking a casual glance at the Moon, it seems as fixed as the stars. But observation of either the Moon or the stars over a period of several hours will reveal their diurnal daily motion across the sky. The Moon rises and sets each day. An observer who watches the Moon over the course of many days will notice the Moon moving not only with the stars, but among them. Every month, the Moon completes one fewer pass across the sky than the stars have completed.
We see this because of the Moon's orbit about the Earth. As the Moon progresses through its orbit, its rising and setting times change. Each day, the Moon rises and sets fifty minutes later than the day before. The moon usually takes 27 days to rotate once on its axis. So any place on the surface of the moon experiences about 13 days of sunlight, followed by 13 days of darkness.
Temperatures on the Moon range from C at night to C during the day. For example if you were standing on the surface of the moon during sunlight hours it would be blazing hot. When the sun goes down, the temperature automatically drop degrees in just a matter of moments. Furthermore, there are craters around the North and South poles of the moon which never seen the sunlight.
These dark places would always be as cool as C. However, there are nearby mountain peaks that are covered in continuous sunlight, and would always be hot. The "dividing line" between the light and dark halves of the globe is called the terminator, as it terminates the area of darkness and also that of daylight. Typically, one-half of the Moon will be lit up by the Sun, while the half facing away from the Sun remains dark. The only exception occurs during a lunar eclipse, when the Earth blocks the light falling on the lit side of the Moon.
The part illuminated by the Sun is not, it should be emphasized, always the same portion of the Moon's surface! Like the Earth, the Moon turns on its axis, exposing different areas at different times. In combination with the orbital revolution of the Moon around the Earth, this phenomenon creates the phases of the Moon as seen from Earth. The phrase "Dark side of the Moon" arose before the age of artificial satellites and the back side of the Moon could not be observed. Hence, the that one side was unknown or "dark". However, at the North and South poles, the height of the sun above the horizon varies by more than 3 degrees over the course of the year.
In other words, it affects the percentage of sunlit regions and surface temperatures at the poles. Furthermore, the coldest areas are located in doubly shadowed regions inside small craters, in which they are located within the permanently shadowed regions of larger craters. Temperatures are as low as 35K C or F in these areas, even at noon on the warmest day of the year.
Some half of the Moon is always illuminated but the fraction of the illuminated part or the Moon's phases directly depend on the relative positions of the Earth, Moon, and Sun. Simply put, it's a matter of how much of the daylight side of the Moon we can see from our current viewing angle. The phase will depend on how much of the side facing toward us is illuminated at any given time.
The sketch below illustrates the phases of the moon for various Earth-Moon-Sun positions the Sun is presumed to be off of the diagram to the right:. Next to each "Moon" is a black-and-white sketch of the phase as it would be seen from Earth when the Moon is in that position.
When the Moon is between the Earth and the Sun, the sunlit side of the Moon is facing completely away from us, and therefore we have the dark "New Moon". When the Moon reaches the other side of the Earth, the sunlit side will be fully toward us, and we have the "Full Moon". As the Moon moves from New to Full and the sunlit side grows increasingly large, we say the Moon is waxing; as we see less, in the decline from Full to New Moon, we say it is waning. Because a half of the half illuminated Moon can be seen, this is referred to as a "quarter Moon".
When the Moon is waxing and reaches this position, it's called the "first quarter Moon"; when waning, the "third quarter Moon. When more than a quarter-moon is visible, it's referred to as a "gibbous moon", again, waxing or waning. The Moon's orbit and rotation speed is just such that the Moon always shows the same side to Earth, aside from only a slight "wobble.
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- MMXII © Astronomical Society of the Pacific.
- Books by Martin Nicholson (Author of The New Biggles Companion)?
- Believe and Youre There, vol. 6: When Ammon Was a Missionary.
Western society has long imagined a face in the markings — the "Man in the Moon.