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'Habitable & Dead Zones' of the Milky Way

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  • derhexer@aol.com
    URL to an interesting article in Daily Galaxy _http://tinyurl.com/7gwjqkx_ (http://tinyurl.com/7gwjqkx) More solid research into habitable and non-habitable
    Message 1 of 1 , Jan 1, 2012
      URL to an interesting article in Daily Galaxy
      _http://tinyurl.com/7gwjqkx_ (http://tinyurl.com/7gwjqkx)

      More solid research into habitable and non-habitable zones and eras

      The article
      New findings from diverse fields are are being brought to bear one of the
      central questions of the 21st century: How common is life in the universe?
      Where can it survive, Will it leave a fossil record, How complex us it. The
      list below moves several key features of the Universe's habitable zones and
      "off-the-chart" of likely places to search for life.

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      Peter Ward and Donald Brownlee, both of the University of Washington have
      outlined a short list of conditions needed:
      Right distance from a star; habitat for complex life; liquid water near
      surafce; far enough to avoid tidal lock; right mass of star with long enough
      lifetime and not too much ultraviolet; stable planetary orbits; right planet
      mass to maintain atmosphere and ocean with a solid molten core and enough
      heat for plate tectonics; a Jupiter-like neighbor to clear out comets and
      asteroids; plate tectonics to build up land mass, enhance bio-diversity, and
      enable a magnetic field; not too much, nor too little ocean; a large moon
      at the right distance to stabilize tilt; a small Mars-like neighbor as
      possible source to seed Earth-like planet; maintenance of adequate temperature,
      composition and pressure for plants and animals; agalaxy with enough heavy
      elements, not too small, elliptical or irregular; right position the
      galaxy; few giant impacts like had 65 million years ago; enough carbon for life,
      but not enough for runaway greenhouse effect; evolution of oxygen and
      photosynthesis; and, of course, biological evolution.
      In stark contrast, the listing of "dead zones" compiled for Rare Earth -Why
      Complex Life is Uncommon in the Universe by Ward (Professor of Geological
      Sciences and Curator of Paleontology) and Brownlee (Professor of Astronomy
      and member of the National Academy of Sciences).
      Early Universe: The most distant known galaxies are too young to have
      enough metals for formation of Earth-size inner planets. Hazards include
      energetic quasar-like activity and frequent super-nova explosions.
      Elliptical Galaxies: Stars are too metal-poor. Solar mass stars have
      eveloved into giants that are too hot for life o inner planets.
      Globular Clusters: Although they contain millions of stars, the stars are
      too metal poor yo have inner planets as large as`earth. Solar mass stars
      have evolved to giants that are too hot for life on inner planets.
      Small Galaxies: Most of the stars are too metal deficient.
      Centers of Galaxies: Energetic star building and black-hole processes
      prevent development of complex life.
      Edges of Galaxies: Where most stars are too metal poor.
      Planetary Systems with "Hot Jupiters": Inward spiral of the giant planets
      drives the inner planets into the central star.
      Planetary Systems with Giant Planets in Eccentric Orbits: Unstable
      environments. Some planets lost to space.
      Future Stars: Uranium, potassium, and thorium too rare to provide sufficent
      heat to drive plate tectonics.
      Three years ago, astronomers at the European Southern Observatory in Chile
      announced that they had found what might be the first habitable planet
      outside the solar system. Known as Gliese 581c, the planet is only five times
      as massive as the Earth and inhabits a rare sweet zone around a dim red star
      in the constellation Libra where it is neither too hot nor too cold for
      liquid water.
      Gliese is but a cosmic hop, skip, and jump from Earth -only some 20 light
      years away (or 120 trillion miles!). Voyager 1, now leaving the solar system
      at a speed of about 39,000 miles per hour, would need more than 300,000
      years to travel that far. Or, maybe someday we'll actually invent a Star
      Trek-type transporter that reassembles our atoms and transports us to the
      farthest reaches of the Cosmos.
      For decades, scientists have been debating the conditions that are needed
      to replicate an Earth-like probability of complex beyond the microbial leve
      l. There's not much doubt in the minds of most astrobiologist that based on
      extremophile life we've discovered recently on Earth (see prior posts
      below), that life on the microbial level will be discovered sometime in the next
      twenty years on Mars or on one of Jupiter or Saturn's moons.
      The three recent key findings for astrobiology are extremophiles,
      extrasolar planets, and a sense that water may be more ubiquitous even in our own
      solar neighborhood (in meteors like the Mars' Lafayette, Europa, and the ice
      frost on polar Mars). This picture has evolved quite suddenly with
      1300-plus extrasolar planets found in just the last decade (and none known before
      around 1995)."


      (I reject your reality and substitute my own)

      [Non-text portions of this message have been removed]
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