The Space Shuttle has been the dominant machine in the U.S. space program for thirty years and has generated a great deal of interest among space enthusiasts and engineers. This book enables readers to understand its technical systems in greater depth than they have been able to do so before. The author describes the structures and systems of the Space Shuttle, and then follows a typical mission, explaining how the structures and systems were used in the launch, orbital operations and the return to Earth. Details of how anomalous events were dealt with on individual missions are also provided, as are the recollections of those who built and flew the Shuttle. Many photographs and technical drawings illustrate how the Space Shuttle functions, avoiding the use of complicated technical jargon. The book is divided into two sections: Part 1 describes each subsystem in a technical style, supported by diagrams, technical drawings, and photographs to enable a better understanding of the concepts. Part 2 examines different flight phases, from liftoff to landing. Technical material has been obtained from NASA as well as from other forums and specialists. Author Davide Sivolella is an aerospace engineer with a life-long interest in space and is ideally qualified to interpret technical manuals for a wider audience. This book provides comprehensive coverage of the topic including the evolution of given subsystems, reviewing the different configurations, and focusing on the solutions implemented.

What if one of the most thrilling stories in the history of science turned out to be wrong? Can urban legends creep into the hallowed grounds of scientific history? As incredible as it may sound, the story of one of the most important elements in modern times helium - has been often misrepresented in books, encyclopedias, and online sources, despite the fact that archival materials tell a different story. Open the entry for Helium in any encyclopaedia and you will read a false story that has been repeated over the years. Encyclopaedia Britannica, for example, says that helium was discovered by the French astronomer Pierre Janssen while observing a total solar eclipse from India in 1868. Apparently he noticed something new in the spectrum of the sun, which he thought was the signature of an undiscovered element.
The truth is that Janssen never saw any sign of a new element during his observations in India. His reports and letters do not mention any such claim.
Other sources would have you believe that helium was jointly discovered by Janssen and Norman Lockyer, a British scientist, and that their discovery letters reached Paris the same day, one sent from India, and the other from England.
Again, the truth is completely different. Two letters from Lockyer and Janssen did reach Paris the same day in 1868, but their letters did not mention any new element. What they had discovered was a new way of observing the Sun without a solar eclipse. This would ultimately lead to the discovery of helium, in which Lockyer would play a prominent role, but not Janssen.
At the same time, Norman Robert Pogson, a disgruntled British astronomer stationed in India did notice something peculiar during the eclipse. He was the first one to notice something odd about the spectrum of the Sun that day, and his observations would prove crucial to Lockyer s own investigations of helium. But Pogson s report was never published in any peer reviewed journal and it languished on the desk of a local British officer in colonial India.
This book tells the real story behind the discovery of helium, along with biographical sketches of the scientists and descriptions of the milieu in which they worked. It will convey the excitement, confusion, and passion of nineteenth century scientists, using their own words, from their letters and reports.
The Story of Helium and the Birth of Astrophysics chronicles one of the most exciting discoveries ever made and explains why it also marked the birth of a new branch of science called astrophysics. "

'Sarah Cruddas is a gifted writer and Look Up is an inspired book. I am hopeful that we will never stop looking up.' Apollo 11 astronaut Michael Collins Most of us have never been to space. To date, of the more than 100 billion humans that have ever existed, fewer than 600 humans have ever left Earth. But the exploration of space is the most significant thing we will ever do as a species. Sarah Cruddas has been looking to the skies her entire life. Her childhood was spent staring at the Moon and hearing stories of the space race, and she worked in a fruit factory to fund her love of the subject. Her subsequent career studying astrophysics, and becoming a television host and space journalist has seen her report on space exploration and chase launches across the world. In Look Up Sarah explains why she has always been a passionate advocate for why space should matter - to everyone. From our ancestors who first painted patterns of the stars in caves, to the US and Soviet pioneers who first forged a path beyond our planet, Sarah Cruddas explores the stories and sacrifices that humankind has made to understand more about our place in the universe. And even today, when Moon walking and people in space suits seem less relevant to us than climate change and conflicts here on Earth, she shows how everything from medicine to mobile phones is affected by space technology, and how a new generation of entrepreneurs have kick-started a new story with the stars. This is an inspirational and enlightening introduction to the importance of space to everyone, and why we should all learn to Look Up.

The authors, leading representatives of Russian space research and industry, show the results and future prospects of astronautics at the start of the third millennium. The focus is on the development of astronautics in Russia in the new historical and economic conditions. The text spotlights the basic trends in space related issues before moving on to describe the possibilities of the wide use of space technologies and its numerous applications such as navigation and communication, space manufacturing, and space biotechnology. The book contains a large amount of facts described in a way understandable without specialist knowledge. The text is accompanied by many photographs, charts and diagrams, mostly in color.

Rock legend and experienced amateur astronomer Brian May joins the legendary expert Sir Patrick Moore to tell the story of the Universe from the moment time and space came into existence at the Big Bang, through to the infinite future and the ultimate fate that awaits us. Many of the pictures of the Universe obtained by instruments such as the Hubble Space Telescope or the Very Large Telescope in Chile are beautiful enough to be considered works of art in their own right. This book presents them in context, and uses extraordinary new artworks to explain the mind-blowing theories from the cutting edge of astronomy in a way that everyone can understand.

There are at least 48 identified prehistoric stone circles in Scotland. In truth, very little is known about the people who erected them, and ultimately about what the stone circles were for. Most stone circles are astronomically aligned, which has led to the modern debate about why the alignment was significant. The megaliths certainly represented an enormous co-operative effort, would at the very least have demonstrated power and wealth, and being set away from any dwellings probably served a ceremonial, or perhaps religious, purpose.
Observations at the site of the stone circles, of solar, lunar, and stellar events, have already cast light on some of the questions about the construction and use of ancient megalithic observatories.
In his capacity as manager of the Parks Department Astronomy Project, author Duncan Lunan designed and built the first astronomically aligned stone circle in Britain in over 3,000 years. 'The Stones and the Stars' examines the case for astronomical alignments of stone circles, and charts the development of a fascinating project with a strong scientific and historical background. The work was documented in detail by the artist and photographer Gavin Roberts, and this archive has been added to since - so an appropriate selection of illustrations will bring the project vividly to life."

From prehistoric times, mankind has looked up at the night sky, and puzzled at the changing positions of the stars. How far away they are is a question that has confounded scientists for centuries. Over the last few hundred years, many scientific careers and considerable resources have been devoted to measuring their positions and motions with ever increasing accuracy. And in the last two decades of the 20th century, the European Space Agency developed and launched the Hipparcos satellite, around which this account revolves, to carry out these exacting measurements from space.

What has prompted these remarkable developments? Why have governments been persuaded to fund them? What are scientists learning from astronomy's equivalent of the Human Genome Project? This book traces the subject's history, explains why such enormous efforts are considered worthwhile, and interweaves these with a first-hand insight into the Hipparcos project, and how big science is conducted at an international level. The involvement of amateur astronomers, and the Hipparcos contributions to climate research, death stars' passing close to the Sun, and the search for extra-solar planets and even intelligent life itself, are some of the surprising facets of this unusual space mission.

From the Big Bang to the Gaia Mission, this is a very personal history of the universe through the author's favourite 100 stars. Astronomer Florian Freistetter has chosen 100 stars that have almost nothing in common. Some are bright and famous, some shine so feebly you need a huge telescope. There are big stars, small stars, nearby stars and faraway stars. Some died a while ago, others have not even yet come into being. Collectively they tell the story of the whole world, according to Freistetter. There is Algol, for example, the Demon Star, whose strange behaviour has long caused people sleepless nights. And Gamma Draconis, from which we know that the earth rotates around its own axis. There is also the star sequence 61 Cygni, which revealed the size of the cosmos to us. Then there are certain stars used by astronomers to search for extra-terrestrial life, to explore interstellar space travel, or to explain why the dinosaurs became extinct. In 100 short, fascinating and entertaining chapters, Freistetter not only reveals the past and future of the cosmos, but also the story of the people who have tried to understand the world in which we live.

Emigrating Beyond Earth puts space colonization into the context of human evolution. Rather than focusing on the technologies and strategies needed to colonize space, the authors examine the human and societal reasons for space colonization. They make space colonization seems like a natural step by demonstrating that if will continue the human species' 4 million-year-old legacy of adaptation to difficult new environments. The authors present many examples from the history of human expansion into new environments, including two amazing tales of human colonization - the prehistoric settlement of the upper Arctic around 5,000 years ago and the colonization of the Pacific islands around 3,000 years ago - which show that space exploration is no more about rockets and robots that Arctic exploration was about boating!

"New Eyes on the Universe - Twelve Cosmic Mysteries and the Tools We Need to Solve Them" gives an up-to-date broad overview of some of the key issues in modern astronomy and cosmology. It describes the vast amount of observational data that the new generation of observatories and telescopes are currently producing, and how that data might solve some of the outstanding puzzles inherent in our emerging world view. Included are questions such as: What is causing the Universe to blow itself apart? What could be powering the luminous gamma-ray bursters? Where is all the matter in the Universe? Do other Earths exist? Is there intelligent life out there? The renowned author explains clearly, without recourse to mathematics, why each question is puzzling and worthy of research. Included in the study of the wide range of sensitive and powerful instruments used by scientists to try and solve these problems are ones which capture electromagnetic radiation and 'telescopes' for cosmic rays, neutrinos, gravitational waves, and dark matter. This book discusses twelve areas of active astronomical research, ranging from the nature of dark energy to the existence or otherwise of extraterrestrial civilizations, and devotes one chapter to each topic. Although astronomers tackle each of these questions using information gleaned from all possible wavelengths and sources (and this is emphasized throughout the book), in this work the author dedicates each chapter to a particular observational method. One chapter covers X-ray telescopes for investigating black holes, while another uses infrared telescopes to learn more about planetary information.

This book shows amateur astronomers how to use one-shot CCD cameras, and how to get the best out of equipment that exposes all three color images at once. Because this book is specifically devoted to one-shot imaging, "One-Shot Color Astronomical Imaging" begins by looking at all the basics - what equipment will be needed, how color imaging is done, and most importantly, what specific steps need to be followed after the one-shot color images are taken. What is one-shot color imaging? Typically, astronomical cooled-chip CCD cameras record only one color at a time - rather like old-fashioned black & white cameras fitted with color filters. Three images are taken in sequence - in red, blue, and green light - and these are then merged by software in a PC to form a color image. Each of the three images must be taken separately through a suitable color filter, which means that the total exposure time for every object is more than tripled. When exposure times can run into tens of minutes or even hours for each of the three colors, this can be a major drawback for the time-pressed amateur. "One-Shot Color Astronomical Imaging" describes the most cost-effective and time-efficient way for any amateur astronomer to begin to photograph the deep-sky.

This book is, ina sense, a sequel to David Seargent's first Springer book "Weird Astronomy" (2010). Whereas "Weird Astronomy" extended over a broad range of purely astronomical topics, the present work concentrates on phenomena closer to home; the atmospheric and "shallow space" events as opposed to deep space events. The line between astronomy and meteorology is blurred - a fact that is discussed in "Weird Weather." It is not primarily a book of "wonders" or of the unexplained, although some of the topics covered remain mysteries. It is primarily directed toward those who are fascinated by climate and weather, and who are open-minded when considering Earth's climate, what drives it, and what are the causes of climate change. The author, David A. J. Seargent, presents the facts with a balanced and scientific approach.

"Weird Weather: Tales of Astronomical and Atmospheric Anomalies" is about strange, unusual, and apparently inexplicable observations of the air and sky. Primarily these are in the Earth's atmosphere, but there are corresponding phenomena in the atmospheres of other planets of the Solar System - lightning on Venus, Jupiter, and Saturn, whirlwinds and dust storms of Mars, and auroras on Jupiter. Topics include anomalous lights, anomalous sounds, spectacular effects of cloud illumination by the Sun or Moon, lightning phenomena, electrophonic sounds of lightning, aurora and meteors, tornado and whirlwind phenomena on Earth and Mars, usual atmospheric effects, mirages, and the possible astronomical influences on cloud and climate."

Classic telescopes are of interest to amateur astronomers for a variety of reasons. There are the dedicated collectors, but there are also many amateurs who love the nostalgia they inspire. These telescopes "feel" different from any contemporary telescope and perhaps have a unique ability to reconnect the owner to a bygone age of craftmanship. This book takes a look at traditional telescopes built by the great instrument makers of the 18th and 19th centuries, particularly the dynastic telescope makers, including Dollond, Alvan Clark, Thomas Cooke & Sons, and Carl Zeiss. Also included are lesser luminaries such as John Brashear, John Calver, William Wray, Henry Fitz, and William Henry Mogey. 'Classic Telescopes' covers the key features of the telescopes designed by these manufacturers, and shows how a heady combination of market trends, instrument condition, and pedigree will dictate their prices at auction. 'Classic Telescopes' also shows the reader how to find real bargains! Interviews with top classic telescope collectors (and users) provide the best tips of prospecting for a genuine acquisition.

In physics, the idea of extra spatial dimensions originates from Nordstom s 5-dimensional vector theory in 1914, followed by Kaluza-Klein theory in 1921, in an effort to unify general relativity and electromagnetism in a 5 dimensional space-time (4 dimensions for space and 1 for time). Kaluza Klein theory didn t generate enough interest with physicist for the next five decades, due to its problems with inconsistencies. With the advent of supergravity theory (the theory that unifies general relativity and supersymmetry theories) in late 1970 s and eventually, string theories (1980s) and M-theory (1990s), the dimensions of space-time increased to 11 (10-space and 1-time dimension).

There are two main features in this book that differentiates it from other books written about extra dimensions: The first feature is the coverage of extra dimensions in time (Two Time physics), which has not been covered in earlier books about extra dimensions. All other books mainly cover extra spatial dimensions. The second feature deals with level of presentation. The material is presented in a non-technical language followed by additional sections (in the form of appendices or footnotes) that explain the basic equations and formulas in the theories. This feature is very attractive to readers who want to find out more about the theories involved beyond the basic description for a layperson. The text is designed for scientifically literate non-specialists who want to know the latest discoveries in theoretical physics in a non-technical language. Readers with basic undergraduate background in modern physics and quantum mechanics can easily understand the technical sections.

Part I starts with an overview of the Standard Model of particles and forces, notions of Einstein s special and general relativity, and the overall view of the universe from the Big Bang to the present epoch, and covers Two-Time physics. 2T-physics has worked correctly at all scales of physics, both macroscopic and microscopic, for which there is experimental data so far. In addition to revealing hidden information even in familiar "everyday" physics, it also makes testable predictions in lesser known physics regimes that could be analyzed at the energy scales of the Large Hadron Collider at CERN or in cosmological observations."

Part II of the book is focused on extra dimensions of space. It covers the following topics: The Popular View of Extra Dimensions, Einstein and the Fourth Dimension, Traditional Extra Dimensions, Einstein's Gravity, The Theory Formerly Known as String, Warped Extra Dimensions, and How Do We Look For Extra Dimensions?"

Where were the amino acids, the molecules of life, created: perhaps in a lightning storm in the early Earth, or perhaps elsewhere in the cosmos? This book argues that at least some of them must have been produced in the cosmos, and that the fact that the Earthly amino acids have a specific handedness provides an important clue for that explanation. This book discusses several models that purport to explain the handedness, ultimately proposing a new explanation that involves cosmic processing of the amino acids produced in space. This book provides a tour for laypersons that includes a definition of life, the Big Bang, stellar nucleosynthesis, the electromagnetic spectrum, molecules, and supernovae and the particles they produce.

This handbook is a guide to exploring the classical night sky and its wonderful telescopic sights. All 88 officially recognized constellations are presented in natural groups which are related by their origin and location in the sky. Each group is explained by a fascinating story which tells what each constellation represents, how it appears in the sky, and why the other constellations of the group are close by, or related in some other manner. Some of these stories are classical myths which show how and why ancient cultures saw the constellations as related groups. Others are about more modern astronomers who sought recognition by filling in the gaps between the ancient constellations with inventions of their own. Both types of stories are crafted to make the constellation groups memorable, so that amateur astronomers can not only locate and recognize the constellations more easily, but also be able to pinpoint the celestial objects they contain more quickly.

Specific instructions are given for finding each constellation, how to spell and pronounce the constellation and star names, plus the origins of the star names. Finder charts show each constellation group and a large area of sky around the group. These charts also indicate pointer stars which aid in finding the constellations.

More detailed charts show how each constellation figure is visualized through simple line drawings. For each constellation, there is a table of about 10 to 30 telescopic objects selected to include a wide range of difficulty. Some can be glimpsed with the unaided eye, others require a 12 or 14 inch telescope. All the most prominent telescopic objects are included, plus a varied selection of interesting, but much more difficult objects. The tables include each object s celestial coordinates, type, size, brightness, other information specific to each type of object, and a recommendation of the appropriate telescope size needed for good viewing.

There are also photographs of constellations and telescopic objects, detailed locator charts for the hard-to-find objects, and plots of binary star orbital motions. The same charts used to show the constellation figures are repeated, with the addition of symbols indicating the locations of all the selected telescopic objects.

An index and seven appendices help the user find specific objects or classes of objects.

The birth and evolution of our solar system is a tantalizing mystery that may one day provide answers to the question of human origins. This book tells the remarkable story of how the celestial objects that make up the solar system arose from common beginnings billions of years ago, and how scientists and philosophers have sought to unravel this mystery down through the centuries, piecing together the clues that enabled them to deduce the solar system's layout, its age, and the most likely way it formed.

Drawing on the history of astronomy and the latest findings in astrophysics and the planetary sciences, John Chambers and Jacqueline Mitton offer the most up-to-date and authoritative treatment of the subject available. They examine how the evolving universe set the stage for the appearance of our Sun, and how the nebulous cloud of gas and dust that accompanied the young Sun eventually became the planets, comets, moons, and asteroids that exist today. They explore how each of the planets acquired its unique characteristics, why some are rocky and others gaseous, and why one planet in particular--our Earth--provided an almost perfect haven for the emergence of life.

From Dust to Life is a must-read for anyone who desires to know more about how the solar system came to be. This enticing book takes readers to the very frontiers of modern research, engaging with the latest controversies and debates. It reveals how ongoing discoveries of far-distant extrasolar planets and planetary systems are transforming our understanding of our own solar system's astonishing history and its possible fate.

From small steps to giant leaps, A Galaxy of Her Own tells fifty stories of inspirational women who have been fundamental to the story of humans in space, from scientists to astronauts to some surprising roles in between.

From Ada Lovelace in the nineteenth century, to the women behind the Apollo missions, from the astronauts breaking records on the International Space Station to those blazing the way in the race to get to Mars, A Galaxy of Her Own reveals extraordinary stories, champions unsung heroes and celebrates remarkable achievements from around the world.

Written by Libby Jackson, a leading UK expert in human space flight, and illustrated with bold and beautiful artwork from the students of London College of Communication, this is a book to delight and inspire trailblazers of all ages.

Packed full of both amazing female role models and mind-blowing secrets of space travel, A Galaxy of Her Own is guaranteed to make any reader reach for the stars.

This star guide enables amateur astronomers to focus on a class of object, and using an observation list that begins with the easiest object, find and move progressively over a period of months to more difficult targets. Includes detailed descriptive summaries of each class of object. Amateur astronomers of all levels will find this book invaluable for its broad-ranging background material, its lists of fascinating objects, and for its power to improve practical observing skills while viewing many different types of deep-sky objects. This new edition of A Field Guide to Deep-sky Objects brings in a correction of out-of-date science along with two new chapters; Transient objects, and Naked-Eye Deep Sky Objects. This edition adds up-to-date information and on the objects mentioned above. This new edition of A Field Guide to Deep-sky Objects brings in a correction of out-of-date science along with two new chapters; Transient objects, and Naked-Eye Deep Sky Objects. This edition adds up-to-date information and on the objects mentioned above.

Observing the Messier Objects with a Small Telescope contains descriptions and photographs of the 103 Messier objects, with instructions on how to find them without a computerized telescope or even setting circles. The photographs show how the objects appear through a 127mm Maksutov (and other instruments, where applicable). The visual appearance of a Messier object is often very different from what can be imaged with the same telescope, and a special feature of this book is that it shows what you can see with a small telescope. It will also contain binocular descriptions of some objects. Messier published the final version of his catalog in 1781 (it contains 103 different objects), a catalog so good that it is still in common use today, well over two centuries later. In making a catalog of all the 'fixed' deep-sky objects that observers might confuse with comets, Messier had succeeded in listing all the major interesting deep-sky objects that today are targets for amateur astronomers. Messier's telescope (thought to be a 4-inch) was, by today's amateur standards, small. It also had rather poor optics by modern standards. Thus - and despite the fact that he was a master observer - all the things Messier saw can be found and observed by any observer using a commercial 127 mm (5-inch) telescope. Observing the Messier Objects with a Small Telescope lets the reader follow in Messier's footsteps by observing the Messier objects more or less as the great man saw them himself!

I wrote this book because I wanted to learn more about interstel lar flight. Not the Star Trek notion of tearing around the Galaxy in a huge spaceship-that was obviously beyond existing tech nology-but a more realistic mission. In 1989 I had videotaped Voyager 2's encounter with Neptune and watched the drama of robotic exploration over and over again. I started to wonder whether we could do something similar with Alpha Centauri, the nearest star to the Sun. Everyone seemed to agree that manned flight to the stars was out of the question, if not permanently then for the indefinitely foreseeable future. But surely we could do something with robotics. And if we could figure out a theoretical way to do it, how far were we from the actual technology that would make it happen? In other words, what was the state of our interstellar technology today, those concepts and systems that might translate into a Voyager to the stars? Finding answers meant talking to people inside and outside of NASA. I was surprised to learn that there is a large literature of interstellar flight. Nobody knows for sure how to propel a space craft fast enough to make the interstellar crossing within a time scale that would fit the conventional idea of a mission, but there are candidate systems that are under active investigation. Some of this effort begins with small systems that we'll use near the Earth and later hope to extend to deep space missions."

Grappling with Gravity explores the physiological changes that will occur in humans and the plants and animals that accompany humans as we move to new worlds, be it to colony in the emptiness of space or settlements on the Moon, Mars, or other moons or planets. This book focuses on the biomedical aspects, while not ignoring other life-changing influences of space living. For example, what happens to people physiologically in the microgravity of space, where weight and the direction "up" become meaningless? Adapting to microgravity represents the greatest environmental challenge that life will have encountered since our ancestors moved from the seas to solid Earth. Away from Earth the human body will begin almost immediately to adapt and change, to be able to function in these strange environments. As a person adapts in space he or she will become less fit to live on Earth.

If you have ever wondered how we get from the awesome impersonality of the Big Bang universe to the point where living creatures can start to form, and evolve into beings like you, your friends and your family, wonder no more. Steve Miller provides us with a tour through the chemical evolution of the universe, from the formation of the first molecules all the way to the chemicals required for life to evolve. Using a simple Hydrogen molecule - known as H-three-plus - as a guide, he takes us on a journey that starts with the birth of the first stars, and how, in dying, they pour their hearts out into enriching the universe in which we live. Our molecular guide makes its first appearance at the source of the Chemical Cosmos, at a time when only three elements and a total of 11 molecules existed. From those simple beginnings, H-three-plus guides us down river on the violent currents of exploding stars, through the streams of the Interstellar Medium, and into the delta where new stars and planets form. We are finally left on the shores of the sea of life. Along the way, we meet the key characters who have shaped our understanding of the chemistry of the universe, such as Cambridge physicist J.J. Thomson and the Chicago chemist Takeshi Oka. And we are given an insider's view of just how astronomers, making use of telescopes and Earth-orbiting satellites, have put together our modern view of the Chemical Cosmos.

This book follows the evolutionary trail all the way from the Big Bang 13.7 billion years ago to conscious life today. It is an accessible introductory book written for the interested layperson anyone interested in the big picture coming from modern science. It covers a wide range of topics including the origin and evolution of our universe, the nature and origin of life, the evolution of life including questions of birth and death, the evolution of cognition, the nature of consciousness, the possibility of extraterrestrial life and the future of the universe. The book is written in a narrative style, as these topics are all parts of a single story. It concludes with a discussion on the nature and future of science.

The Casual Sky Observer's Pocket Guide offers an observing program for occasional amateur observers looking for some quick, fun astronomy adventures under the stars. In the real world, where time for observing is limited, the weather is seldom perfect, and expensive equipment is not an option, amateur astronomy may not be seen as a worthwhile activity. However, portable and quick-to-set-up instruments are available. A pair of binoculars or a small telescope fills the bill. And the way to make the most of these instruments is described in the Casual Sky Observer's Pocket Guide. Not only does the book feature the best and brightest showpieces of the heavens; it also provides a great deal of physical and environmental data as well as lots of fascinating information and beautiful illustrations that provide a unique perspective on the many treasures within and beyond our home galaxy, the Milky Way - stars, star clusters, other galaxies, and nebulae, all within reach of binoculars or a small telescope.