Worlds without End : The Exploration of Planets Known and Unknown (Helix Books Series)

This changed somewhat such that planetary sciences became near to an equal footing when instrumentation and measurement became sufficiently precise to begin detecting planets around other stars. Suddenly there was a new universe opening up around each and every star, at least it seemed so for a time. We've reached the point now where announcement of new planets around other stars not only no longer makes headlines, but may no longer warrant a mention in the press beyond the professional journals.

Lewis' book, `Worlds Without End: The Exploration of Planets Known and Unknown' helped to fill a gap in my knowledge about the direction and breadth of the new planetary studies. Published back in 1998, it is already somewhat out of date given the speed with which discoveries are occurring in this field, but it still serves as a great, accessible and interesting primer to the study of planets both `at home' and `abroad'.

Lewis explores the different kinds of planets, from rocky types like Mercury to the big gaseous giants like Jupiter and Saturn. This survey includes the study of satellites, or planets around planets, as Lewis terms them. There are more moons around Jupiter and Saturn than planets around the Sun (if one does not include asteroids). These make for fascinating trips, too.

It is no surprise that these types of giant planets were the first to be discovered around other planets. He talks about the different kinds environments for stars, and in so doing gives a short course on other aspects of general astronomy such as overall galactic motion, the different types of stars and their life cycles, and the different kinds of groupings of stars. For example, a planet around a star in a globular cluster, clumps of stars that exist surrounding some galaxies but to a certain extent separate from those galaxies (rather like gated communities might be to larger urban settings), would have spectacularly starry nights, even if the stars in the cluster were relatively small, and the close fly-bys of other stars would be a million times more frequent, such that the environment of the planet would constantly be shifting dramatically as the orbit would constantly change - stars may even `steal' planets away from one another!

Lewis in his final chapter sets the stage for ongoing planetary science, theoretical and observational. He sees that in the not too distant future we may even be able to directly detect terrestrial-type planets (much `detection' today is done indirectly, measuring shifts in movement, light patterns, etc.). He gives a nod to the SETI project here (without mentioning it by name) in talking about the remote possibility of increasingly sensitive radio telescopes to detect artificial broadcast transmissions.

The one drawback of this text is the lack of graphic images. There are eight pages of plates, but none in colour - given the dramatic photography available of planets in our solar system from exploratory ships, and the stunning photography available of objects beyond the solar system from major observatories and the Hubble Space Telescope, one wonders why these weren't incorporated. Also, a few charts and graphs might have been helpful at certain points in the discussion to give a quick idea of figures or comparative values.
April 09, 2004

What it lacks is some sort of summary at the end! I was quite surprised that nothing like it was supplied. A total of how many sun could hold life. I hope that the writer rewrites it with such a chapter.
March 21, 2002

He presents several mind-bending -- yet scientifically feasible -- worlds for our consideration. "Earthissimo," for example, made me put the book down, lean back in my chair, and SAVOR the elegance of the science for several minutes. Wonderful!

BUT, like Lewis's otherwise excellent _Mining the Sky_, he doesn't include any graphs, table or illustrations. (He has a few artistic rendering in the middle, which are different.)

A few graphs or tables would have clarified his arguments and saved pages of dense, descriptive text.

Good book, mind-twisting science, poor presentation: 4 stars.
September 25, 2001