Life on Earth and Other Planetary Bodies, edited by Arnold Hanslmeier, Stephan Kempe and Joseph Seckbach

Rating: 10/10

So far we know of one object in the Solar System, that has had the necessary conditions to support life for more than 500 million years, possibly even longer. It has been historically just recently that we have begun looking at life not just for classification purposes, but rather to try and understand the history of our blue-green planet and what was the planet like when life arose.

"Life on Earth and Other Planetary Bodies" is a collection of articles about life, habitability and astrobiology, that should find a place on everyone's reading-list who's interested in the possibility of extraterrestrial life and the quickly evolving field of astrobiology and search for exoplanets and naturally also SETI.

In this book you can get a comprehensive overview of exoplanets, that was written by Eike W. Guenther. The history of searching for exoplanets - when, how and around which kind of objects they were found, what were the methods used and what sort of planets can be found with different methods. With the radial velocity method we might be able to find giant planets orbiting their star in just a few days in a really close orbit, and the planet might not ever transit the star. However if the planet does transit as well, we can gain more information combining the radial velocity method and transit method - for example the density of the planet can be determined.

Although we haven't yet found any planets that scientists would think might harbor the same kind of life that we know on Earth, even if we'd find one, it might be inhabitable through some cosmic catastrophe, that wouldn't let life evolve or would kill it all. From the Earth's history we know of several mass exitinction events, that might give clues to what might happen - a large asteroid impact changing the climate of the planet drastically could easily wipe out life. In Harold Hanselmeier's "Habitability and Cosmic Catastrophes" you can find out what were some of the catastrophic events in the Solar System and what are some that might happen in a different star system. These events lead us on to think about the habitability of a planet in regard to it's location both in the star system and in the galaxy, and the reader can find out more about the habitable zones in galaxies and planetary systems.

These are just some of the more general overviews that this collection has to offer. One can get acquainted with some of the other possible places where life might exist now or might have existed. For example the Saturn system - although the planet doesn't lie in the habitable zone, might life still be possible on one of it's moons that is either heated by tidal energy or inner radiation? Could there be life under the dense atmosphere of Titan? Or on the icy Enceladus?

But we can also look closer to home - look at some of the exceptional lifeforms that can exist in extreme conditions - in really cold icy worlds or near warm lava caves - if life is possible there, why not somewhere else, on a planet where the conditions are nothing like the Earth?

And the SETI enthusiasts aren't left out, there's enough for them to read about as well in Rob Hengeveld's "The Likelihood of Extraterrestrial Intelligence". SETI's been running for about 50 years now, with no evidence of extraterrestrial intelligence to show. Maybe it just doesn't exist?

"Life on Earth and Other Planetary Bodies" is a thrilling albeit scientific work that sheds light to all aspects of astrobiology, from analyzing the necessary conditions for life on Earth, to finding other planets and to the more biological part of how organic compounds can be generated on a lifeless world and what kind of conditions were present on Earth when first organic molecules formed.

All in all it's definitely a fascinating book. The best part about the book might be that you get to know some of the objects of the Solar system a lot more from the habitability aspect.

Labels: astrobiology, book review, Life on Earth and Other Planetary Bodies, SETI