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----------------- 1809 - Life Beyond Earth?
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- Is there life beyond Earth?
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- How about beyond the Milky Way Galaxy?
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- Earth seems the only likely place in our Solar System. Mars is too dry. Venus is too hot. Where can we find the Goldilocks’ porridge just right?
- Let’s start by defining a solar system with a “habitable zone” being planetary orbits (moons will be discussed later). A habitable zone is the range of distances from the star where a rocky planet could maintain liquid water on the surface.
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- Because stars vary with age and temperature these zones vary as well.
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- A rocky planet covers the range from 2 times radius to 10 time mass of Earth.
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- Mars is in our Solar System’s habitable zone yet it lacks standing water on its surface.
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- A habitat would change surface life in the very air we breath in a detectable way. Where an exoplanet passes in front of its star ( a transit) the light from the star passes through the exoplanets atmosphere. A spectroscopy measurement can detect the components in that atmosphere. Carbon dioxide ( CO2) and water (H2O) are the primary greenhouse gases to look for.
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- Hydrogen and oxygen are the 1st and 3rd most abundant elements in the Universe (Helium is 2nd). H2O should also be abundant.
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- The 4 rocky planets in our inner Solar System were dry, being intensively radiated by the higher energy earlier Sun. Out near Jupiter the radiation temperature was low enough for water and ice to survive. Earth’s water had to come later from showers of icy asteroids and comets.
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-Today water cover 67% of our surface and makes up 67% or our body weight. The oceans have an average depth of 2.5 miles which would fill a sphere 800 miles in diameter. Yet water is only 0.02% of the mass of the Earth. If our planet were a Boeing 777 all the water would weigh less that a single passenger, 300,000 kilograms. ( or, 186,410 pounds / 180 pounds = 1000 times heavier).
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- 30% of the planet’s mass is the nickel - iron core. Potentially this could hold even more water then the mantle in the form of hydrogen bond with oxygen outside of the immense heat and pressure . The estimate is that the mantle alone contains at least another ocean’s worth of water in hydrated rocks and minerals. Still this only gets us to 0.04% of the planet’s mass.
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- Earth seems to have collided with a Mars-size body 4,500,000 years ago. That is how the Moon got formed. That impact would have flash-boiled any water oceans at that time. Earth’s water had to be delivered later.
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- Planets should not be the only search for life. Saturn’s moon Titan has lakes of liquid methane that could act as a solvent in place of water.
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- Jupiter’s moon Europa is an icy body with a subsurface liquid ocean,
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- Potentially these could be habitable worlds that exist beyond the “habitable zones”?
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- Spotting vegetation covering the land would be a strong suggestion for life. Science would need to able to detect chlorophyll.
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- NASA has recorded more than 4,000 exoplanets. Yet, the field of exoplanet discoveries is so young compared to the field of astronomy.
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- There is a chance that Blackholes switched on habitable planets allowing them to support complex life. High-energy particles from Blackholes and supernovae could play a critical role in life’s evolution.
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- On early Earth at some point the bath of Cosmic Ray flux dropped off enough for life on Earth to flourish
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- Supernovae explosions were more common in the early Universe. The rates of star births were much higher then. Storms of radiating exited from galactic Blackholes as they consumed surrounding matter.
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- In the early Universe everything was close together. It took billions of years of Cosmic expansion to pull things apart and thin out the deadly soup of radiation. Universe expansion is another important aspect for life to exist.
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- In addition, it is the supernovae explosions that produce the heavier elements like oxygen and nitrogen that are in our atmosphere.
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- It is this thick atmosphere that protects us from the radiation power of Cosmic Rays. If a Cosmic Ray dose is high enough it can kill something. But, a lesser amount can cause mutations that allow evolution to produce many different species.
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- Blackholes at the heart of galaxies can swell to 50 billion Solar Mass. Gigantic Blackholes form disks of orbiting gas. A huge amount of radiation is generated as the swirling gas falls in to the Blackhole.
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- 50 billion Solar Mass is about the maximum size a Blackhole can reach through the accretion disk process. However, Blackholes can get bigger by merging with other Blackholes. There would be no life without them.
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- Request these Reviews for more information:
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- #1690 - Discovering Life - It may be plausible that somewhere a sulfur-cycle might replace our carbon-cycle?
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- #1695 - What are the odds you are able to read this?
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- #1191 - Every cell in the body is connected to a tiny blood vessel that provides the nutrients it needs.
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- #1016 - Life coming from space and landing on Earth?
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- #1151 - how did God start life on Earth? Belief that life had a simple beginning and evolved its complexity through natural selection.
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- #844 - Drake’s Equation - calculations for the parameters for life.
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- #813 - Life from comets?
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- #348 - Life - evolution over 4.6 billion years. ( 10 pages )
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----- 707-536-3272 ---------------------- Wednesday, January 13, 2016 -----
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