Customer Reviews

The Telescope: Its History, Technology, and Future

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This is an odd book. It was written by an Aussie who now works at the US Air Force Academy. It was originally published in Australia and New Zealand, then republished by Princeton University Press. And I can't figure out who the target reader is.

It is a short book, a bit over 200 pages, broken up into short chapters with magazine article level treatments of various subjects. Despite its brevity, there are many times the author claims he could write so much more if he only had the space. He often alludes to being much more knowledgeable than the reader, yet some of the chapters don't quite get it right, and others give the impression he is simply digesting what he has read in other popular treatments.

He spends a few pages on astronomy before telescopes, then a few pages on the early history of the telescope. Both subjects are covered in more detail in many texts and popular astronomy books. These are followed by a brief sketch of how different types of telescopes work from a geometrical optics standpoint, and then a chapter called "The perfect telescope", which is really a very short, very introductory discussion of diffraction. A chapter with the cute but misleading title "When good telescopes go bad" then discusses why real telescopes can't be built to perform as well as reading a few page article on telescopes would suggest. (Aberrations and all that.)

Andersen then moves into the sensors that record what the telescope is looking at. One chapter skims over cameras, spectrometers, photometers, and polarimeters. He then has a chapter on interferometry. While written at roughly the high school physics level, it starts with the warning "While interferometry is the next big thing for telescopes, it is a complex subject, so some readers may want to skip over the material." I doubt many people would make it this far into the book without being able to understand the very basic treatment that follows.

The cute title "So you want to build an observatory?" briefly covers the difficulty of building a large mirror, choosing a site, and the mechanical engineering of a large device. These appear to be topics he wanted in the book but didn't know where to put them. Next we are in space with the Hubble Space Telescope. If you don't know the history of how they screwed up the primary mirror this includes a relatively good brief history. But the overall history of Hubble here is thin, and there are better treatments.

He's then off on "Advanced telescope techniques", which covers lightweighting, active optics, segmented primaries, adaptive optics, and laser guide stars. But what is on offer is a series of vignettes thrown together rather than integrated into the areas where they enable telescope advancement.

Next come a couple of chapters on applications other than astronomy for telescopes. Laser communication and remote sensing are tossed together in the first. The very first sentence claims "Telescopes are instruments for gathering and intensifying light." Telescopes concentrate light; "intensify" means something else. The next page claims "This increased waveform complexity (called bandwidth) ...". Complexity and bandwidth are different things. You can transmit a very simple signal at very high bandwidth (for example, a sine wave), or a very complex signal at very low bandwidth (for example, Beethoven's Ninth Symphony). (In the latter case you won't be enjoying the music in real time, but you can transmit it at low bandwidth with suitable patience. And for those old enough to remember, an LP is a pretty low bandwidth medium.)

The surveillance section is truly odd. Andersen has apparently surfed the internet and applied flights of fancy to imagine what US spy satellites can do. While it is possible that his speculation about satellite capability is correct (although it seems far fetched), his assertion that such a satellite's altitude has "a reasonable value of 200 km" is hard to swallow. At that altitude there is enough residual atmospheric drag that nothing stays up very long. He finishes the surveillance section with laser weapons. Yes, they use telescopes. But I don't see how they are tied to surveillance.

Next comes another mishmash called "Non-traditional observatories". First he talks about liquid mirror telescopes, which fit the title. But then he goes into solar telescopes which are, to my thinking, quite traditional. He mentions observations back to 1609, and includes a picture of a dedicated solar telescope (the 150 ft tower on Mt Wilson) finished in 1912! After explaining that the "emphasis of this book has been on optical telescopes, as the extension into other parts of the spectrum would constitute an overwhelming amount of subject matter", he then describes observing the Cherenkov radiation caused by high energy gamma rays entering the atmosphere. I suppose it can at least be argued that conventional telescopes are used for this purpose. But this is followed with a discussion of detecting gravity waves! Gravity waves aren't even light, although the detectors do use laser interferometry to (it is hoped) detect them. There is no room in his short book to discuss radio or x-ray telescopes at all, but he finds room for gravity wave detection? I think he just writes about what interests him, which is his prerogative, just don't expect a complete or rigorous coverage of "The Telescope".

He concludes with brief discussions of some recent discoveries in astronomy and some future telescope projects.

While there are some interesting bits to this book, there is no unified story. There are also some things he doesn't quite get right. On the other hand, I can't think of another book that gives a better short introduction to the topics he choses to cover. There are certainly better books on astronomical telescopes, but they give little or no coverage to other uses for telescopes. Andersen's coverage is nether very complete nor always accurate, but it is another viewpoint. I didn't personally learn much from this book, but some readers might. Just approach with caution.

More than a few amateur astronomers- and I count myself in the group- find nearly as much fascination with the hardware of astronomy and space exploration as they do with the actual viewing. A good fraction of my library is taken over by books on telescope construction, the history of telescopes, testing optics, ray tracing and so forth.

Here's a fascinating and delightful book that is a bit different than the typical book about telescopes. It's written for the educated reader, who isn't afraid to see a little algebra, or some ray tracing diagrams, and because of that it's far more informative and useful than the typical all-about book that tries to explain everything by metaphor. There's historical material, exellent explanations of topics like how achromatic and apochromatic lenses work, telescope technologies used in astronomy, satellites, and elsewhere, and future technologies- spinning mirrors, liquid mirrors and other cutting-edge (and some yet untried) techniques.

It's not just limited to telescopes used in astronomy, either. There's material on terrestrial telescopes, surveillence satellites, industrial appplications and more.

This volume is hIghly recommended for technology junkies, fans of the history of technology, those interested in aerospace, and anyone who is looking for something short of a college text on optics that does a good job of really explaining how optics work.

I have read a number of books on telescope history and technology over the recent past, but this one has got to be one of the very best. The scientific principles are very clearly explained with just sufficient depth so as to allow the interested reader to understand the basic concepts without becoming overwhelmed with unnecessary details. Just about everything is covered, from how a telescope works, its limitations, e.g., diffraction limit, atmospheric turbulence, aberrations, etc., its site selection and its use, all the way to the state-of-the-art technology and techniques that are used to observe the faintest of objects such as extra solar planets. Several topics are discussed here that I have not seen discussed in the other books that I have read on this topic. Appendices are included to explain some math/geometry basics, the nature of electromagnetic radiation and even suggestions on buying one's own telescope. The author's writing style is friendly, authoritative and a model of clarity. Because of this, the book could be enjoyed by anyone - especially those with a fascination for telescopes and astronomy. However, it is likely to be relished the most by science buffs and amateur astronomers.

For the 400th anniversary of the telescope, physicist Geoff Andersen celebrates with this little volume. He says today's models are still the same "simple" instruments they were back then. Just a lot bigger.
Galileo did not invent the telescope. It isn't certain who did, but the one who got the ball rolling was Hans Lippershey, a spectacle maker in Holland.
Simple or not, it took a long time to get an instrument big enough to see the Universe. It is startling to recall that the proof that the Universe contains more than one galaxy wasn't published until 1929.
It's equally startling to recall that in those days it was still possible to do astronomy just outside the little town of Los Angeles.
Today, with telescopes costing hundreds of millions of dollars, only the very best locations will do. That means a high mountain with clear, still air and not too many neighbors with electric lights.
Mauna Kea and Haleakala in Hawaii are among the very best, although the best of the best may be in Antarctica. Andersen comments that it's doubtful astronomers will prefer Antarctica to Hawaii or Chile, which are the most popular spots for viewing the northern and southern skies, respectively.
Haleakala gets scant mention in "The Telescope," which is a bit of a surprise. The Air Force telescopes there are not the biggest -- although 50 years ago they would have been contenders -- but they are the fastest. That is in terms of tracking fast objects crossing the sky.
Tracking asteroids that might collide with Earth is now perhaps the most alarming and practical use for a telescope, although it could not have been foreseen by Lippershey.
Asteroids were discovered two centuries ago.
There are lots of ways to build a telescope, including putting one in space. But the Earth-bound telescope still has its merits.
Some of the proposals for the next generation of 'scopes are truly astonishing. Their designers are running out of words to label them: "very large" and "giant" have been taken. For the past decade, the dreamers have been sketching a 100-meter telescope. The Kecks at Mauna Kea are 10 meters (32.5 feet) in diameter.
The 100-meter scope is called OWL for "overwhelmingly large telescope."
Andersen says its designers see no particular engineering obstacles to building it.
The OWL's perch has not been determined but it won't be in Hawaii. Its sponsor is the European Organization for Astronomical Research in the Southern Hemisphere, so it will have to be below the Equator.
More and more, telescope builders have to deal with claims that they are intruding onto sacred land. The biggest flaw in Andersen's book is that he treats these claims without skepticism.
Many religions' sacred mountains are imaginary. Where chthonic religions do revere real mountains, the sacred spots are usually at lower levels or even inside. Peaks are not often sacred, although not every such claim will be spurious.

This book would probably appeal to those wanting somewhat greater depth in understanding how telescopes and associated instruments work than is common in a popular science book.

The author, a physicist working at the U. S. Air Force Academy, describes the different ways a telescope can be built (refractors, reflectors, Schmidt-Cassegrians, and so on) and the instruments they use. The author emphasizes that resolution (how far apart two objects need to be for us to tell that there are two, rather than one, thing out there) and light gathering ability limit our ability to detect objects much more than magnification does.

Until the last few decades, not much could be done to improve resolution (because atmospheric turbulence was the most important cause of lower resolution), but light gathering could be increased by making larger mirrors. The new technique of making mirrors out of separate segments has allowed for much larger mirrors, a technique made practical by the concurrent development of computers to keep these segments properly aligned. Electronic controls also allow for correction of the minute changes in mirror shape due to gravity. Furthermore, the technique of adaptive optics, in which the shape of the overall mirror is adjusted to keep the image of a guide star or of laser light reflected off of sodium atoms in the out atmosphere, sharp has greatly improved for ground based telescopes. In addition, putting telescopes into orbit also avoids the problem of atmospheric factors reducing resolution.

The adaptive optics technqiues were originially developed for spy satellites and were declassified in the early 1990s to the benefit of astronomers. The author shows using simple calculations and some publicly available information that the incredible resolutions that I've heard attributed to spy satellites are in fact plausible.

The author mainly discusses astronomical telescopes, but also describes the physics behind spy satellites and lidar. Lidar is a remote sensing technique, analagous to radar, but using laser pulses rather than radio or microwaves. It can be used to make extremely accurate topographical "maps" and can also be used to detect wind shear, a useful thing to know around airports as arriving and departing planes are very vulnerable to sudden severe gusts. As the receiving device for lidar is a telescope, there is a connection to the main topic. In terms of instruments used in conjunction with telescopes, the author describes such imaging techniques as photographic imulsions (mostly out of date now), digital devices like CCD (similar to a digital camera), spectrometry, and inferometry. The last technique can allow for higher resolution for part of the field of view of an object. It is also useful in searching for dim objects, such as planets, next to bright ones.

The author keeps the equations to a minimum. The equation he uses most is the one for calculating the theoretical resolution of a telescope, given its diameter. Two appendices cover common units of distance, luminosity and energy (the first appendix) and the characteristics of light.

I very much enjoyed this book. It walks through the history and many interesting details of telescope construction. I don't have any special optics or astronomy background, just a basic engineering background, and I found the level to be about right, making an interesting tour through an area novel to me.

People interested in another treatment of the hubble space mirror fiasco should see Inviting Disaster: Lessons From the Edge of Technology.

A nicely done book. Organization is a bit odd, but workable. The only reason i couldn't give it 5 stars was it omits the two GREAT telescope designs of the 20th century that ultimately solved most of the observer's problems (both are only briefly mentioned), the Ritchey-Chretien aplanatic Cassegrain and the Schmidt catadioptric camera. I have yet to find a good general audience treatment of these two great designs, or the stories of the eccentric geniuses that created them...

Still a very good book and recommended...

Geoff Andersen has compiled a fascinating and thorough description of the modern telescope. It treats the history of the instrument and goes into depth analysing the manner in which telescopes function. It further discusses the limitations on the instrument as well as the rather sizeable developments challenges that have happened in the field of astronomical optics primarily since the late 1940's.

I emailed the author. He stated that he enjoyed researching the book. It shows!

I could not put this book down and I highly recommend it.

Francis J. O'Reilly