About the Book | Reviews | Authors | Contact
Bookmark and Share


Adopting a popular style, this book shows the fundamental change in our perception of the universe by covering the full spectrum of light, emphasising what humans cannot see. Using spectacular colour images constructed from observations with telescopes operating from radio to gamma-ray wavelengths, the book lifts the veil on the hidden universe.

Until 400 years ago, when Galileo first turned his telescope towards the heavens, our perception of the Universe was limited by our eyes and the thoughts and ideas arising from what we saw. The huge leap in capability that even such a simple instrument could realise set us on the path of creating ever more powerful instruments to satisfy our voracious appetite for knowledge.

Nonetheless, until the mid-20th century our view of the Universe was limited almost entirely to the narrow band of light that could penetrate the Earth’s atmosphere and was visible either to our eyes or to sensitive photographic plates loaded at the focus of increasingly large telescopes. With these resources alone, the discoveries were still stupendous: the mapping of our Solar System, the identification of the mechanism that makes stars shine and determines how long they live, the realisation that there are a multitude of galaxies like our own Milky Way and that they constitute an expanding Universe. The profound revolution in physics during the first half of the century brought with it the understanding of how light is emitted and how to read the subtle messages it carries concerning the physical state and chemical composition of stars and nebulae.

Stimulated by the development of radar for military use, the first major expansion of our view was the result of the development of radio astronomy, leading to the realisation that the Universe could look very different to us when seen through new “eyes” tuned to a different type of radiation.

The launch of Sputnik in 1957 paved the way for astronomy’s escape from the absorbing and distorting effects of the Earth’s atmosphere. With truly clear skies, generations of exploratory spacecraft and orbiting observatories have produced a wondrous and often breathtakingly beautiful view of a Universe whose richness could not have been imagined. A string of new discoveries has come from this fleet of new space-based instruments and observatories, and each new insight has been firmly placed within the existing framework of understanding by astronomers. Meanwhile the impressive arsenal of today’s ground-based facilities bears witness to the continuing success of the modern large and highly evolved versions of the traditional telescope.

This book will enable you to peer through these exotic new telescopes and see some of the more spectacular images that have become the icons of modern astronomy. By expanding your vision beyond the visible into an array of “colours” that span the full spectrum of light, you will be able to gain a more complete picture of the Universe than has ever been possible before. These images are truly a legacy to be appreciated by everyone. Obtained using facilities built by governments and public institutions across the globe, they allow us all to better understand our place in a spectacular Universe, once hidden, but now revealed.

This book is divided into nine chapters dealing with various aspects of the unseen Universe. The first three discuss the way we perceive the Universe, using our eyes and with telescopes on the ground and in space. The next five chapters each discuss a wavelength band, starting with the most familiar, visible light, and then moving outwards on each side of the spectrum into the less familiar: infrared, ultraviolet, radio/microwaves and X-rays/gamma rays. In the final chapter we attempt to gather the individual threads of the story into one, somewhat coherent, view of the totality of the multi-wavelength Universe.


  • Hardcover
  • 145 pages
  • Publisher: Wiley-VCH
  • Lots of full-page photographs
  • Similar in style to the popular Hubble — 15 years of discovery book
  • Aimed at laypeople
  • Size: 247 mm (W) x 297 mm (H)
  • Available in English, German, Finnish and Japanese



Buy it at Wiley-VCH -
- English
- German
Buy it at the Hubble Shop
- English
- German






Sample chapters for download

Ours is a Universe of light…The light we see defines the way we understand the world around us. What is solid and what is insubstantial, what is bright and what is dark, what is beautiful and what is ugly. All of these concepts derive from visual cues. But since our vision is inextricably linked to the nature of the Sun, in a real sense even our aesthetics are deeply rooted in astronomy. Perhaps it is no wonder that images of the Universe can trigger such a sense of awe. But the light from the Universe contains so much more than the light we can see for ourselves...
Astronomy is an observational science. Apart from the use of space probes in the Solar System, it is not possible to carry out experiments in situ, and information must be gleaned from light signals collected by telescopes and measured with instruments such as cameras and spectrometers, which spread out the light into its constituent wavelengths and allow a closer study. Most of the telescopes in existence observe the heavens from the ground — often from remote mountain tops to get above as much of the Earth’s disturbing atmosphere as possible. But ground-based telescopes are much more than the well known visible-light telescopes that collect light from remote stars and galaxies with gigantic mirrors...
Astronomical observatories in space have revolutionised our knowledge of the Universe. They are one amongst the many types of satellites launched since the beginning of the space age, devoted to a great variety of applications including Earth observation, communication and broadcasting, navigation and military, right up to fully habitable space stations. Space observatories give access to light that is not visible from the ground and provide an undisturbed view of the star- and galaxy-studded sky. Expensive yes, but unbeatable in the search for the elusive photons from the hidden Universe.
The visible part of the electromagnetic spectrum is the astro-nomical base camp. This is where people first started to look at the sky with the naked eye many thousands of years ago and it remains the reference point for research taking place in all other wavelength bands. The visible band is home to the majority of the starlight and, although many scientists and engineers are finding ingenious ways to exploit the non-visible bands, there are still many secrets left to explore in the visible...
The infrared band lies just beyond the deepest red we can see. This band of the electromagnetic spectrum is a window onto a cool, dust-filled Universe. By allowing us to peer through the obscuring dust, strewn between the stars like an interstellar fog, it reveals distant reaches of our Milky Way hidden outside the visible spectrum.
At longer infrared wavelengths the dust itself becomes luminous, showing us a different facet of the wispy tendrils of tiny grains that drift through the vastness of space between the stars. Shrouded by these dust clouds, young stars form and planets like our own are assembled.
Ultraviolet light falls beyond the limits of what we can see at the blue end of the spectrum. In human terms the word ultraviolet calls to mind images of sore skin resulting from overexposure to the Sun, an indication of the high energy of this form of light.The hottest stars in the Universe are brightest in ultraviolet light. The dusty clouds that give birth to these massive, luminous ob-jects are in turn sculpted and shaped under the onslaught of the high energy photons they emit. Ultraviolet light shows us where the action is in star formation — amongst the young, the massive and the hot stars.
Seen with radio telescopes, the sky is unrecognisable to a visible-light astronomer. In place of the stars in the Milky Way there are objects sprinkled throughout the entire Universe. Radio sources are rare but often intrinsically very powerful, making them de-tectable at very large distances. The emissions from these radio galaxies, quasars and titanic stellar explosions are the result of immensely energetic sub-atomic particles speeding through regions of twisted magnetic fields. This process is quite different from that producing the heat radiation from the surfaces of stars and it leads us to the sites of some of the most violently energetic action in the Universe.
Beyond the ultraviolet we reach the highest energies of the electro magnetic spectrum. From X-rays to the even more energetic gamma rays, the increasingly rare photons have to be counted one by one. Only the most dramatic phenomena will generate light at this far end of the spectrum. This means that X-rays and gamma rays are our window into the study of cata-clysmic processes such as the explosions of massive stars and the neutron stars and black holes they leave behind, as well as hot plasmas in galaxy clusters and in nearby stars.
Astronomy began as a visual science. For thousands of years, humans used little more than their eyes to observe and record the light from the stars. All this changed 400 years ago when Galileo first turned his telescope towards the heavens, dramatically expanding our ability to see and understand the Universe. Yet, for the next 350 years, the potential of this magnificent device was limi ted to that tiny sliver of the spectrum visible to human eyes. As we have seen in this book, a series of technological advances over the past 50 years or so has given us access to the hidden Uni verse: the cosmic domains of radio waves, infrared light, ultraviolet light, X-rays and gamma rays. Layer by layer, the cosmic onion has been peeled away to reveal a richness and complexity that was unimaginable from our long-held visible perspective. We show the fundamental change in worldview brought about by expanding our perception to include the full spectrum of light.