The companion website to Welcome to the Universe launches today

Welcome to the UniverseWe’re thrilled to launch this beautiful companion website to the highly anticipated new book, Welcome to the Universe by Neil DeGrasse Tyson, Michael Strauss, and Richard Gott.

If you’ve ever wondered about the universe and our place in it, then this elegant mini-tour of the cosmos is for you. Divided into three parts called ‘Stars, Planets and Life,’ ‘Galaxies,’ and ‘Einstein and the Universe,’ the site is designed to take you on a journey through the major ideas in Welcome to the Universe. We hope you learn something new and exciting about outer space. If you find something interesting and would like to share, please do! The site is set up to make sharing interesting tidbits on social media easy. Want to learn more? The site also includes information on where to learn more about each topic. Keep an eye out for the book in October 2016.


Welcome to the Universe: An Astrophysical Tour by Neil deGrasse Tyson, Michael A. Strauss & J. Richard Gott from Princeton University Press on Vimeo.

Gravitational waves making waves at Princeton

Today marks a new era in cosmology, astronomy, and astrophysics. The main page of the Einstein Papers Project website reports, “Gravitational waves do exist, as has been announced today with great joy by the scientists of the LIGO collaboration, after more than two decades of intensive experimental work.”

The cosmic breakthrough, which proves Einstein’s 100 year old prediction, has resulted in a tremendous response across the scientific community and social media. Scientific websites everywhere are already debating the meaning of the discovery, the #EinsteinWasRight hashtag has been bantered about on Twitter; You Tube featured a live announcement with over 80,000 people tuning in to watch (check it out at 27 minutes).



Princeton University Press authors Jeremiah Ostriker and Kip Thorne had a bet about gravitational wave detection in the 80s. Today when we contacted him, Ostriker, author of Heart of Darkness, was ebullient:

“The LIGO announcement today and the accompanying papers are totally persuasive. We all believed that Einstein had to be right in predicting gravitational waves, but to see them, so clean and so clear is marvelous. Two independent instruments saw the same signal from the same event, and it was just what had been predicted for the in-spiral and merger of two massive black holes.

A quarter of a century ago I had a bet with Kip Thorne that we would not see gravitational waves before the year 2000 – and I won that bet and a case of wine. But I did not doubt that, when the sensitivity of the instruments improved enough, gravitational waves would be found.  Now the skill and perseverance of the experimentalists and the support of NSF has paid off.

Hats off to all!!!”

But was Einstein always a believer in gravitational waves? Daniel Kennefick, co-author of The Einstein Encyclopedia says no:

“One hundred years ago in February 1916, Einstein mentioned gravitational waves for the first time in writing. Ironically it was to say that they did not exist. He said this in a letter to his colleague Karl Schwarzschild, who had just discovered the solution to Einstein’s equations which we now know describe black holes. Today brings a major confirmation of the existence both of gravitational waves and black holes. Yet Einstein was repeatedly skeptical about whether either of these ideas were really predictions of his theory. In the case of gravitational waves he soon changed his mind in 1916 and by 1918 had presented the first theory of these waves which still underpins our understanding of how the LIGO detectors work. But in 1936 he changed his mind again, submitting a paper to the Physical Review called “Do Gravitational Waves Exist?” in which he answered his own question in the negative. The editor of the journal responded by sending Einstein a critical referee’s report and Einstein angrily withdrew the paper and resubmitted it elsewhere. But by early the next year he had changed his mind again, completely revising the paper to present one of the first exact solutions for gravitational waves in his theory. So his relationship with gravitational waves was very far from the image of the cocksure, self-confident theorist which dominates so many stories about Einstein. Because of this, he would have been thrilled today, if he were still alive, to have this major confirmation of some of the most esoteric predictions of his theory.”

Here at Princeton University Press where we recently celebrated the 100th anniversary of Einstein’s theory of general relativity, the mood has been celebratory to say the least. If you’d like to read the Einstein Papers volumes that refer to his theory of gravitational waves, check out Document 32 in Volume 6, and Volume 7, which focuses on the theory. Or, kick off your own #EinsteinWasRight celebration by checking out some of our other relevant titles.

Traveling at the Speed of Thought: Einstein and the Quest for Gravitational Waves
by Daniel Kennefick


Relativity: The Special and the General Theory, 100th Anniversary Edition
by Albert Einstein

relativity 100 years

The Meaning of Relativity: Including the Relativistic Theory of the Non-Symmetric Field
by Albert Einstein


Einstein Gravity in a Nutshell
by A. Zee


The Road to Relativity: The History and Meaning of Einstein’s “The Foundation of General Relativity” Featuring the Original Manuscript of Einstein’s Masterpiece
by Hanoch Gutfreund & Jürgen Renn.

The Road to Relativity

The Curious History of Relativity: How Einstein’s Theory of Gravity Was Lost and Found Again
by Jean Eisenstaedt

the curious history of relativity jacket

 An Einstein Encyclopedia
by Alice Calaprice, Daniel Kennfick, & Robert Sculmann


Gravitation and Inertia
by Ignazio Ciufolini & John Archibald Wheeler

gravity and inertia jacket

Einstein’s Jury: The Race to Test Relativity
by Jeffrey Crelinsten

einstein's jury jacket

What Does a Black Hole Look Like?
by Charles D. Bailyn

black hole

Dynamics and Evolution of Galactic Nuclei
by David Merritt

dynamics and evolution of galactic nuclei

The Global Nonlinear Stability of the Minkowski Space (PMS-41)
by Demetrios Christodoulou & Sergiu Klainerman

the global nonlinear stability of the minkowski space

Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics
by Kip S. Thorne & Roger D. Blandford

modern classical physics

The Collected Papers of Albert Einstein, Volume 7: The Berling Years: Writings, 1918-1921
by Albert Einstein

albert einstein

Anna Frebel on the search for the oldest stars

Frebel jacketAstronomers study the oldest observable stars in the universe in much the same way that archaeologists study ancient artifacts on Earth. Stellar archaeologist Anna Frebel is credited with discovering several of the oldest and most primitive stars, and her book, Searching for the Oldest Stars is a gripping firsthand account of her work. Recently she took the time to answer some questions:

What is your main research topic and what is stellar archaeology?

AF: My work is broadly centered on finding the oldest stars in the universe and using them to explore how the first stars and the first galaxies formed soon after the Big Bang. This works because these ancient stars are about 13 billion years old and they are still shining. The universe itself, by comparison, is 13.8 billion years old. I find these ancient stars in the outskirts of the Milky Way galaxy, using a large telescope. I’m also researching how the chemical elements heavier than hydrogen and helium were first created in those early stars, which ultimately allowed Earth to form and to bring about life in the universe.

What is your biggest discovery?

AF: I have been fortunate enough to discover several “record holding stars”. In 2007, I found a 13.2 billion year-old star, which is incredibly old. This followed the 2005 discovery of the chemically most primitive star – a star of the second generation of stars to have formed in the universe. Since then, I have analyzed some incredible ancient stars in dwarf galaxies that orbit the Milky Way galaxy, and together with my team, we have recently beaten said 2005 record, which was enormously exciting.

Why do people say we are made from stardust?

AF: We humans are made from all sorts of different chemical elements, mostly carbon. We breathe oxygen and nitrogen, we wear silver and gold jewelry. All these elements were once, atom by atom, created inside different kinds of stars and their supernova explosions over the course of billions of years. Studying this evolution of the chemical elements in the universe with the help of ancient stars means that I’m literally studying the cosmic origins of the building blocks of life. So we really are closely connected with the universe, far more than we realize.

How did you decide to become a scientist?

AF: From a young age I knew I wanted to study stars. They were just so fascinating to me, these big spheres of gas, fusing new elements to gain energy to shine for eons in the sky. Fortunately, I received good advice during high school on how to become an astronomer. After studying physics until 2002, I turned to astronomy and the rest is history. Today, I take pride in sharing my story with young people and the general public by telling them what astronomers do on a daily basis, and how scientific results are achieved. I am passionate about conveying the importance of science literacy to the young and the young at heart while inspiring them with the beauty and mystery of the cosmos.

What kind of telescope is used for your astronomical observations?

AF: Astronomers use all kinds of different telescopes on Earth as well as from space to peer deep into the cosmos. It depends on the type of project and the brightness of the objects which telescope is best suited. Space observations are being carried out remotely, whereas ground-based observations are still done by the astronomer who has to travel to the telescope. More and more telescopes are becoming automated to enable remote controlled “office observing”.

Anna Frebel in front of the 6.5m Magellan Telescope in Chile.

Anna Frebel in front of the 6.5m Magellan Telescope in Chile.

Are you traveling to any telescopes?

AF: Yes, I regularly fly to Chile to the Magellan Telescopes to carry out my observations. These are some of the largest telescopes in the world and the dark night sky in the Southern Hemisphere is terrific for studying the cosmos. It’s the favorite part of my job and I love discovering new facts about the universe through these observations!

What does it mean when you say you’re going observing?

AF: To use the telescopes, you have to fly to Chile. First to Santiago, then to La Serena and from there is a 2-3h drive up the mountains of the Atacama Desert where the telescopes are. There are guest rooms there for the observers to sleep during the day and the observatory chefs are cooking delicious meals for everyone. Dinner is eaten together by all observers, including the technical staff. It’s a little community with the sole purposes of caring for the telescopes and obtaining exquisite astronomical observations all night long of a breathtaking sky.

What does a typical night at the telescope look like?

AF: All preparations for the night happen during the afternoon while it’s still light outside. After sunset, I usually choose the first targets from my list, which I begin to observe soon after dark. Each star is observed for 10-30 minutes. We immediately inspect each observation and then decide on the fly whether we need more data or not. If we have found an interesting old star we may choose to immediately observe it for a few more hours.

Did anything ever go wrong at the telescopes?

AF: Of course! Mostly when it’s cloudy because then we can’t observe any starlight. This can be very frustrating because it can mean that we have to come back to the telescope a year later to try again. Clouds spell bad luck. Other times, the air layers above the telescope are often not as smooth as is required. This makes the stars twinkle and appear less sharp, which means less good data and longer exposure times. And sometimes there are technical problems with the telescope too.

How do you get your telescope time? Can I go to your telescope and observe, too?

AF: To obtain telescope time, astronomers have to submit a proposal to a committee that selects the best projects and awards them the time. The proposal contains a detailed description of the project and the technical details on what information is being sought. Telescope use is restricted to professional astronomers because of the considerable expense. The cost is about USD 50,000 to 100,000 per night, depending on the telescope, and often paid by various institutions and universities who jointly operate observatories. While this is a lot of money, it’s actually not that much in comparison to many other research facilities.

Are there any special moments at the telescope that you remember in particular?

AF: Yes, going observing is always magical and memorable. Of course I particularly remember big discoveries and the excited nervousness of checking and checking whether we didn’t make a mistake and that the discovery was really what it appeared to be. Then, there have been the frustrating moments of sitting at the telescopes for nights on end listening to the rain and flying home empty-handed. I have been there when severe technical problems and even a bush fire prevented observing during clear nights. But I always associate observing with the most colorful sunsets, the calm and peaceful atmosphere up in the mountains, and of course the sleepless but exciting nights.

Anna Frebel is the Silverman (1968) Family Career Development Assistant Professor in the Department of Physics at the Massachusetts Institute of Technology. She is author of Searching for the Oldest Stars, and has received numerous international honors and awards for her discoveries and analyses of the oldest stars. She lives in Cambridge, Massachusetts.

Business Insider calls Katherine Freese one of the “50 scientists who are changing the world”

The Cosmic CocktailBusiness Insider included Katherine Freese, author of The Cosmic Cocktail, in a list of the 50 scientists who are changing the world. Freese was recognized for her pioneering work in the study of dark matter. Other picks included Andrea Accomazo, the first person to land a probe on a comet, Alan Stern, the principal investigator for NASA’s New Horizons mission,  Cori Bargmann, autism and Alzheimer’s researcher, as well as an impressive lineup of other scientists whose “revolutionary research in human happiness, evolutionary biology, neutrino physics, biotechnology, archeology, and other fields is helping to advance our lives in more ways than we could ever imagine.”

You can read the full feature here, and watch Freese discuss the greatest mysteries of the universe here.

Congratulations, Katherine!

Quick Questions for Charles D. Bailyn, author of What Does a Black Hole Look Like?

Charles BailynCharles D. Bailyn is the A. Bartlett Giamatti professor Astronomy and Physics at Yale University. He is currently serving as Dean of Faculty at Yale-NUS College in Singapore. He was awarded the 2009 Bruno Rossi Prize from the American Astronomical Society for his work on measuring the masses of black holes, and the recipient of several other, equally prestigious awards.

Dr. Bailyn received his B.Sc. in Astronomy and Physics from Yale (1981) and completed his Ph.D. in Astronomy at Harvard (1987). His research interests are concentrated in High Energy Astrophysics and Galactic Astronomy, with a focus on observations of binary star systems containing black holes. His latest book, What Does a Black Hole Look Like? addresses lingering questions about the nature of Dark Matter and black holes, and is accessible to a variety of audiences.

Now, on to the questions!

PUP: What inspired you to get into your field?

Charles D. Bailyn: Like a lot of little kids in the late 1960s, I was fascinated by space travel, and I wanted to be an astronaut. But then someone told me about space sickness – I’m prone to motion sickness, and that sounded pretty awful to me. So “astronaut” morphed into “astrophysicist” – I liked the idea of exploring the universe through math and physics. In college I thought I would work on relativity theory, but I didn’t quite have the mathematical prowess for that, and around that time I found out that the X-ray astronomers were actually observing black holes and related objects. So as a graduate student and post-doc I gradually moved from being a theorist to being an observer. I’ve analyzed data from many of NASA’s orbiting observatories, so I ended up being involved with the space program after all.

What would you have been if not an astronomer?

I’ve always loved music, particularly vocal music, and I’ve spent a lot of time in and around various kinds of amateur singing groups. I could easily see myself as a choral conductor.

What is the biggest misunderstanding that people have about astronomy?

Well, I’m always a bit amused and dismayed when I tell someone that I’m an astronomer, and they ask “what’s your sign?” – as if astronomy and astrology are the same thing. I used to tell people very seriously that I’m an Orion – this is puzzling, since most people know it’s a constellation but not part of the zodiac. At one point I had an elaborate fake explanation worked out about how this could be.

Why did you write this book? Who do you see as its audience?

There seem to be two kinds of books on black holes and relativity – books addressing a popular audience that use no math at all, and textbooks that focus on developing the relevant physical theory. This book was designed to sit in the middle. It assumes a basic knowledge of college physics, but instead of deriving the theory, its primary concerns are the observations and their interpretation. I’m basically talking to myself as a sophomore or junior in college.

“The unseen parts of the Universe are the most intriguing, at least to me.”

How did you come up with the title?

The Frontiers in Physics (Princeton) series like to have questions in the title, and this one is particularly provocative. Black holes by definition cannot be seen directly, so asking what they “look like” is a bit of an oxymoron. But a lot of modern astrophysics is like that – we have powerful empirical evidence for all sorts of things we can’t see, from planets around distant stars to the Dark Matter and Dark Energy that make up most of the stuff in the Universe. The unseen parts of the Universe are the most intriguing, at least to me.

What are you working on now?

I’m turning the online version of my introductory astronomy course into a book – kind of a retro move, turning online content into book format! It will be for a non-scientific rather than a scientific audience. But mostly I’m doing administrative work these days – I’m currently in Singapore serving as the inaugural Dean of Faculty for Yale-NUS College, the region’s first fully residential liberal arts college. The importance of science in a liberal arts curriculum is a passion of mine – after all, astronomy was one of the original liberal arts – and I’m glad to have a chance to bring this kind of education to a new audience, even though it takes me away from my scientific work for a while.

What are you reading right now?

I’ve been following the reading list for our second semester literature core class, starting from Don Quixote and Journey to the West, the first early modern novels in the European and Chinese traditions respectively, ending with Salman Rushdie, who is all about the interaction of East and West. It’s fun being a student again!


Charles D. Bailyn is the author of:

Buy the Book image What Does a Black Hole Look Like? by Charles D. Bailyn
Hardcover | August 2014 | $35.00 / £24.95 | ISBN: 9780691148823
224 pp. | 5 x 8 | 21 line illus.| eBook | ISBN: 9781400850563 | Reviews

A letter from Ingrid Gnerlich, Executive Editor of Physical and Earth Sciences

Photo on 2014-05-14Dear Readers:

As many of you will know, in November 2013, the remarkable astrophysicist, Dimitri Mihalas – a pioneering mind in computational astrophysics, and a world leader in the fields of radiation transport, radiation hydrodynamics, and astrophysical quantitative spectroscopy – passed away.  Though deeply saddened by this news, I also feel a unique sense of honor that, this year, I am able to announce the much-anticipated text, Theory of Stellar Atmospheres:  An Introduction to Astrophysical Non-equilibrium Quantitative Spectroscopic Analysis, co-authored by Ivan Hubeny and Dimitri Mihalas.  This book is the most recent publication in our Princeton Series in Astrophysics (David Spergel, advising editor), and it is a complete revision of Mihalas’s Stellar Atmospheres, first published in 1970 and considered by many to be the “bible” of the field.  This new edition serves to provide a state of the art synthesis of the theory and methods of the quantitative spectroscopic analysis of the observable outer layers of stars.  Designed to be self-contained, beginning upper-level undergraduate and graduate-level students will find it accessible, while advanced students, researchers, and professionals will also gain deeper insight from its pages.  I look forward to bringing this very special book to the attention of a wide readership of students and researchers.

It is also with profound excitement that I would like to announce the imminent publication of Kip Thorne and Roger Blandford’s Modern Classical Physics:  Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics.  This is a first-year, graduate-level introduction to the fundamental concepts and 21st-century applications of six major branches of classical physics that every masters- or PhD-level physicist should be exposed to, but often isn’t.  Early readers have described the manuscript as “splendid,” “audacious,” and a “tour de force,” and I couldn’t agree more.  Stay tuned!

Lastly, it is a pleasure to announce a number of newly and vibrantly redesigned books in our popular-level series, the Princeton Science Library.  These include Richard Alley’s The Two-Mile Time Machine, which Elizabeth Kolbert has called a “fascinating” work that “will make you look at the world in a new way” (The Week), as well as G. Polya’s bestselling must-read, How to Solve It.  In addition, the classics by Einstein, The Meaning of Relativity, with an introduction by Brian Greene, and Feynman, QED, introduced by A. Zee, are certainly not to be missed.

Of course, these are just a few of the many new books on the Princeton list I hope you’ll explore.  My thanks to you all—readers, authors, and trusted advisors—for your enduring support. I hope that you enjoy our books and that you will continue to let me know what you would like to read in the future.

Ingrid Gnerlich
Executive Editor, Physical & Earth Sciences

World Space Week Round-Up #WSW2013

All this week for World Space Week, we’ve been posting excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration, and while that’s an amazing book, we decided that in order to give World Space Week all of the cosmic attention it deserves, we would put together an interstellar round-up to fire up your engines and blast you to infinity… and beyond!

Beyond UFOs
Beyond UFOs: The Search for Extraterrestrial Life and Its Astonishing Implications for Our Future

By: Jeffrey Bennett

This book describes the startling discoveries being made in the very real science of astrobiology, an intriguing new field that blends astronomy, biology, and geology to explore the possibility of life on other planets. This book goes beyond UFOs to discuss some of the tantalizing questions astrobiologists grapple with every day: What is life and how does it begin? What makes a planet or moon habitable? Is there life on Mars or elsewhere in the solar system? How can life be recognized on distant worlds? Is it likely to be microbial, more biologically complex–or even intelligent? What would such a discovery mean for life here on Earth?

Titan Unveiled
Titan Unveiled: Saturn’s Mysterious Moon Explored

By: Ralph Lorenz and Jacqueline Mitton

In the early 1980s, when the two Voyager spacecraft skimmed past Titan, Saturn’s largest moon, they transmitted back enticing images of a mysterious world concealed in a seemingly impenetrable orange haze. Titan Unveiled is one of the first general interest books to reveal the startling new discoveries that have been made since the arrival of the Cassini-Huygens mission to Saturn and Titan.

From Dust To Life
From Dust to Life: The Origin and Evolution of Our Solar System

By: John Chambers & Jacqueline Mitton

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.

Fly Me to the Moon
Fly Me to the Moon: An Insider’s Guide to the New Science of Space Travel

By: Edward Belbruno
With a foreword by Neil deGrasse Tyson

Belbruno devised one of the most exciting concepts now being used in space flight, that of swinging through the cosmos on the subtle fluctuations of the planets’ gravitational pulls. His idea was met with skepticism until 1991, when he used it to get a stray Japanese satellite back on course to the Moon. The successful rescue represented the first application of chaos to space travel and ushered in an emerging new field. Part memoir, part scientific adventure story, Fly Me to the Moon gives a gripping insider’s account of that mission and of Belbruno’s personal struggles with the science establishment.

The Milky Way
The Milky Way: An Insider’s Guide

By: William H. Waller

This book offers an intimate guide to the Milky Way, taking readers on a grand tour of our home Galaxy’s structure, genesis, and evolution, based on the latest astronomical findings. In engaging language, it tells how the Milky Way congealed from blobs of gas and dark matter into a spinning starry abode brimming with diverse planetary systems–some of which may be hosting myriad life forms and perhaps even other technologically communicative species. It vividly describes the Milky Way as it appears in the night sky, acquainting readers with its key components and telling the history of our changing galactic perceptions.

The Universe in a Mirror: The Saga of the Hubble Space Telescope and the Visionaries Who Built It

By: Robert Zimmerman
With a new afterword by the author

The Hubble Space Telescope has produced the most stunning images of the cosmos humanity has ever seen. It has transformed our understanding of the universe around us, revealing new information about its age and evolution, the life cycle of stars, and the very existence of black holes, among other startling discoveries. But it took an amazing amount of work and perseverance to get the first space telescope up and running. The Universe in a Mirror tells the story of this telescope and the visionaries responsible for its extraordinary accomplishments.

Think you know all about missions in space? Take our quiz and find out!
Proud of your score? Tweet it! #WSW2013

“Dreams of Other Worlds”: Chandra and HST #WSW2013

Houston, we have lift off!

All week long for World Space Week, we will be posting exclusive excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration. Each day will include an excerpt from a different chapter(s) about a different unmanned spacecraft, along with a picture of the craft that doubles as an iPhone background!

Today we have two excerpts. The first is from Chapter 10, and it describes some of the leaps and bounds we have been able to make in black hole exploration thanks to Chandra. The second excerpt is from Chapter 11, which talks about what is probably the most famous spacecraft, the Hubble Space Telescope.

Tomorrow will bring another chapter and another adventure, so stay tuned!

chandra99-13Chandra has the sensitivity to detect stellar black holes hundreds of light-years away. Only about twenty binary systems have well-enough measured masses to be sure the dark companion is a black hole, but X-ray observations can be used to identify black holes with fairly high reliability. The examples studied with X-ray telescopes are the brightest representatives of a population of about 100 million black holes in the Milky Way.
X-ray observations have also pushed the limit of our understanding of black holes. In 2007, a research team used Chandra to discover a black hole in M33, a nearby spiral galaxy. The black hole was sixteen times the mass of the Sun, making it the most massive stellar black hole known.32 Moreover, it was in a binary orbit with a huge star seventy times the Sun’s mass. The formation mechanism of the black hole that placed it in such a tight embrace with its companion is unknown. This is the first black hole in a binary system that shows eclipses, which provides unusually accurate measurements of mass and other properties. The massive companion will also die as a black hole, so future astronomers will be able to gaze on a binary black hole where energy is lost as gravitational radiation and the two black holes dance a death spiral as they coalesce into a single beast.
hubble89-13Above all scientific projects, the Hubble Space Telescope encapsulates and recapitulates the human yearning to explore distant worlds, and understand our origins and place in the universe. Its light grasp is 10 billion times better than Galileo’s best spyglass, and many innovations were needed for it to be realized: complex yet reliable instruments, the ability for astronauts to service the telescope, and the infrastructure to support the projects of thousands of scientists from around the world. The facility and its supporters experienced failure and heartache as well as eventual success and vindication.
Hubble’s legacy has touched every area of astronomy, from the Solar System to the most distant galaxies. In the public eye, it’s so well known that many people think it’s the only world-class astronomy facility. In fact, it operates in a highly competitive landscape with other space facilities and much larger telescopes on the ground. Although it doesn’t own any field of astronomy, it has made major contributions to all of them. It has contributed to Solar System astronomy and the characterization of exoplanets, it has viewed star birth and death in unprecedented detail, it has paid homage to its namesake with spectacular images of galaxies near and far, and it has cemented important quantities in cosmology, including the size, age, and expansion rate of the universe.

Think you know all about these missions? Take our quiz and find out!
Proud of your score? Tweet it! #WSW2013

“Dreams of Other Worlds”: Hipparcos and Spitzer #WSW2013

Houston, we have lift off!

All week long for World Space Week, we will be posting exclusive excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration. Each day will include an excerpt from a different chapter(s) about a different unmanned spacecraft, along with a picture of the craft that doubles as an iPhone background!

Today we have two excerpts. The first is from Chapter 8, which talks about the first star charts, which were created by the Greek astronomer, Hipparchus (for whom the Hipparcos was named). The second excerpt is from Chapter 9, explaining some of the adversities Spitzer had to face before it was able to go into space.

Tomorrow will bring another chapter and another adventure, so stay tuned!

HipparcosFor thousands of years, all we’ve known of Hipparchus’s star guide were descriptions by Ptolemy. But astronomer Bradley Schaefer asserts that, indeed, the Farnese Atlas, a statue of the Greek figure Atlas kneeling while holding on his shoulders a globe of constellations, represents the stars and constellations known to the ancient Greeks. He contends that the statue “is the oldest surviving depiction of the set of the original Western constellations, and as such can be a valuable resource for studying their early development.”18 Schaefer realized after a detailed study of the globe that the constellations depicted match the night sky in the era and from the location where Hipparchus lived in 129 BC. As evidence in favor of this possibility, Schaefer writes: “First, the constellation symbols and relations are identical with those of Hipparchus and are greatly different from all other known ancient sources. Second, the date of the original observations is 125 ± 55 BC, a range that includes the date of Hipparchus’s star catalogue (c. 129 BC) but excludes the dates of other known plausible sources.” Schaefer concludes that “the ultimate source of the position information [of the constellations on the globe] used by the original Greek sculptor was Hipparchus’s data.”

SpitzerSpitzer, from its earliest inception, was especially designed for infrared astronomy and is sensitive enough to detect infrared signatures of stars and galaxies billions of light-years away. The space telescope has been instrumental in unveiling small, dim objects like dwarf stars and exoplanets and can even determine the temperature of their slender atmospheres. Originally proposed in the late 1970s as NASA’s Space Infrared Telescope Facility, the Spitzer Space Telescope suffered from uncertainty, a delay after the loss of the space shuttle Challenger, near-cancellation, congressional limbo, budget cuts, and “descoping.” Nevertheless, in 2003 the telescope was finally launched, after being renamed subsequent to a public opinion poll conducted by NASA. The last of NASA’s four Great Observatories, the $800 million telescope was named after Lyman Spitzer, an early advocate of the importance of orbital telescopes.13 After launch, the spacecraft took about 40 days to cool to its operating temperature of 5 Kelvin. Once cooled, it took just an ounce of liquid helium per day to maintain its detectors at their operating temperature. A solar panel facing the Sun serves to gather power and protect the telescope from radiation.

Think you know all about these missions? Take our quiz and find out!
Proud of your score? Tweet it! #WSW2013

“Dreams of Other Worlds”: Stardust and SOHO #WSW2013

Houston, we have lift off!

All week long for World Space Week, we will be posting exclusive excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration. Each day will include an excerpt from a different chapter(s) about a different unmanned spacecraft, along with a picture of the craft that doubles as an iPhone background!

Today we have two excerpts. The first is from Chapter 6, and our excerpt talks about how Stardust was able to keep up with the intense speed of the Wild 2 comet to photograph it. The second excerpt is from Chapter 7, which describes “space weather”, which SOHO is able to track to warn us of any changes in our solar system.

Tomorrow will bring another chapter and another adventure, so stay tuned!

StardustMission controllers tried to sneak up behind Wild 2 to minimize the relative speed of the two objects. Even so Stardust was moving 13,000 mph, or five times the speed of a rifle bullet, as it flew through the glowing coma of the comet. It took seventy-two close-up photographs. That may not seem like many, but keeping the relatively small comet in the camera field of view during such a fleeting and high-speed encounter was a major feat.10 The images showed a surface riddled with depressions with flat bottoms and sheer walls, ranging in size from dozens of meters to several kilometers. The comet itself is irregular in shape and five kilometers in diameter. The features are impact craters and gas vents; ten vents were active when Stardust flew by.
The neatest trick Stardust had up its sleeve was gathering material from the comet tail. […] All of the solid objects in the universe were built from microscopic dust particles—stardust. The probe was designed to capture material too small to see in its eight-minute ride through the comet’s tail and then its long ride home.
SOHOData from SOHO, and increasing concern over the impact of space weather, caused NASA to commission a new study in 2009. The resulting report provides clear economic data to quantify the risk to the near-Earth environment from episodes of intense solar activity. Extreme space weather is in a category with other natural hazards that are rare but have far-reaching consequences, like major earthquakes and tsunamis.34 It’s likely that more than once in the next twenty years there will be an “electro-jet disturbance” that disrupts the national power grid. In the 1989 event, the loss of some portions of the grid put stress on others and led to a cascade affect. The end result was power outages affecting more than 130 million people and covering half the country.
SOHO cannot prevent these natural disasters, but it can give two or three days’ notice of Earth-directed disturbances. And as we become more accurate in anticipating space storms, operators can place satellites in protective modes, shut down or limit power grids, redirect commercial flights, warn oceanic cruise and cargo ships, and place astronauts working on the International Space Station in the safest possible location on the station. Such steps will not only save lives but also protect the information systems that sustain our electronically fragile and networked global community.

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“Dreams of Other Worlds”: Voyager and Cassini #WSW2013

Houston, we have lift off!

All week long for World Space Week, we will be posting exclusive excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration. Each day will include an excerpt from a different chapter(s) about a different unmanned spacecraft, along with a picture of the craft that doubles as an iPhone background!

Today we have two excerpts. The first is from Chapter 4, and our excerpt does its best to describe exactly how far away the Voyager spacecrafts are, and how completely wild that is. The second excerpt is from Chapter 5, which describes the way in which Cassini travels around Saturn without getting sucked into its gravitational pull.

Tomorrow will bring another chapter and another adventure, so stay tuned!

voyager77-13To see why these spacecraft represented such a leap in our voyaging through space, consider a scale model of the Solar System where the Earth is the size of a golf ball. On this scale, the Moon is a grape where the two objects are held apart with outstretched arms. That gap is the farthest humans have ever traveled, and it took $150 billion at 2011 prices to get two dozen men there. Mars on this scale is the size of a large marble at the distance of
1,100 feet at its closest approach. As we’ve seen, it took an arduous effort spanning more than a decade before NASA successfully landed a probe on our nearest neighbor. A very deep breath is needed to explore the outer Solar System. In our scale model, Jupiter and Saturn are large beach balls 1.5 and 3.5 miles away from Earth, respectively, and Uranus and Neptune are soccer balls 7 and 12 miles from the Earth. This large step up in distance was a great challenge for spacecraft designers and engineers. On this scale, the Voyager 1 and 2 spacecraft are metallic “motes of dust” 48 and 37 miles from home, respectively.
cassini97-13Over its core mission, Cassini orbited Saturn 140 times. To see Saturn, its rings, its largest moons, and its magnetosphere from all conceivable angles, Cassini is using its rockets and seventy gravity-assist flybys of Titan to tweak its orbit size, period, velocity, and inclination from Saturn. As the largest moon, Titan isthe most useful in “steering” Cassini around the Saturnian system. Each Titan flyby is engineered to return Cassini into the proper trajectory for its next Titan flyby. Encounters with other moons are performed opportunistically with what’s called a targeted flyby. About fifteen are planned by the end of the mission, half to the intriguing small moon Enceladus. From 2004 through 2011, Cassini did a dizzying hundred flybys, with another dozen completed in 2012. NASA hosts a clock counting down the time until the next swooping visit to a moon and coyly calls these “Tour Dates” to appeal to a younger generation.26 By clever planning, NASA engineers have doubled the length of the mission even though just a quarter tank of fuel remains.

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“Dreams of Other Worlds”: The Mars Rovers #WSW2013

MERHouston, we have lift off!

All week long for World Space Week, we will be posting exclusive excerpts from Chris Impey and Holly Henry’s new book, Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration. Each day will include an excerpt from a different chapter about a different unmanned spacecraft, along with a picture of the craft that doubles as an iPhone background!

Today’s excerpt is from Chapter 3, and it talks about our strategy for learning more about Mars, and what the Mars Rovers, Spirit and Opportunity, are doing to help us with that.

Tomorrow will bring another chapter and another adventure, so stay tuned!

Decoding the Red Planet

As we saw in the last chapter, Mars seems dead to the orbiters that daily send back images of the surface. The atmosphere is tenuous, ultraviolet radiation and cosmic rays scorch the soil, and it rarely gets above freezing even on the balmiest summer day.15 It’s unlikely any form of life could exist on the surface now, but Mars has not always been so inhospitable. NASA’s strategy in searching for life in the Solar System is to “follow the water,” and even if there’s no surface water now, there was in the past. Each of the Mars Exploration Rovers, Spirit and Opportunity, was designed for just a ninety-day mission. In the end, they have vastly exceeded expectations with their indomitable traverses of the forbidding Martian terrain. Think of them as twin robotic field geologists whose primary goal is to search for the signposts of water.16 The record of past water can be found in the rocks, minerals, and landforms on Mars, particularly those that could only have formed in the presence
of water.

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