Rare Earth: Why Complex Life is Uncommon in the Universen November 12, 2002, Dr. John Chambers of the NASA Ames - search Center gave a seminar to the Astrobiology Group at the OUniversity of Washington. The audience of about 100 listened with rapt attention as Chambers described results from a computer study of how planetary systems form. The goal of his research was to answer a dec- tively simple question: How often would newly forming planetary systems produce Earth-like planets, given a star the size of our own sun? By “Ear- like” Chambers meant a rocky planet with water on its surface, orbiting within a star’s “habitable zone. ” This not-too-hot and not-too-cold inner - gion, relatively close to the star, supports the presence of liquid water on a planet surface for hundreds of million of years—the time-span probably n- essary for the evolution of life. To answer the question of just how many Earth-like planets might be spawned in such a planetary system, Chambers had spent thousands of hours running highly sophisticated modeling p- grams through arrays of powerful computers. x Preface to the Paperback Edition The results presented at the meeting were startling. The simulations showed that rocky planets orbiting at the “right” distances from the central star are easily formed, but they can end up with a wide range of water c- tent. |
Contents
Habitable Zones of the Universe | 15 |
Building a Habitable Earth | 35 |
Lifes First Appearance on Earth | 55 |
How to Build Animals | 83 |
Snowball Earth | 113 |
The Enigma of the Cambrian Explosion | 125 |
Mass Extinctions and the Rare Earth Hypothesis | 157 |
The Surprising Importance of Plate Tectonics | 191 |
Other editions - View all
Rare Earth: Why Complex Life is Uncommon in the Universe Peter D. Ward,Donald Brownlee Limited preview - 2003 |
Rare Earth: Why Complex Life is Uncommon in the Universe Peter D. Ward,Donald Brownlee Limited preview - 2000 |
Rare Earth: Why Complex Life is Uncommon in the Universe Peter D. Ward,Donald Brownlee No preview available - 2003 |
Common terms and phrases
2.5 billion abundance accretion appear archaeans asteroid astrobiologists astronomers atmosphere bacteria billion years ago biological body plans Cambrian Explosion carbon dioxide cause cell changes chapter chemical collision comets complex metazoans continental continents crust discovery diversification diversity early Earth Earth history Earth today Earth-like planets Earth’s surface Ediacarans ejected elements energy environment environmental Eucarya eukaryotic evolution evolutionary evolved exist extremophiles formation fossil record galaxy genes giant global greenhouse habitable zone habitats heat hydrothermal hydrothermal vents impact James Kasting Jupiter kilometers land large moon life’s liquid water living major mantle Mars Martian mass extinction material metazoans microbes molecules multicellular nebula number of species occurred oceans orbit organisms origin oxygen perhaps phyla planet’s surface planetary systems plate tectonics produce prokaryotic proteins Rare Earth Hypothesis regions rocks scientists Snowball Earth solar system space stars subduction telescopes temperature terrestrial planets tion Universe volcanic