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Our Unique Planet * With notes provided by David McDonald-Christa McAuliffe Planetarium. http://www.d21c.com/AAALynx/CB/pl/earth.jpg. What is the most unique characteristic of the Earth?. The presence and diversity of life. What factors allow this diversity?.
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Our Unique Planet* With notes provided by David McDonald-Christa McAuliffe Planetarium http://www.d21c.com/AAALynx/CB/pl/earth.jpg
What is the most unique characteristic of the Earth? • The presence and diversity of life What factors allow this diversity?
I. Star/ Solar System Characteristics http://www.mallorcaweb.net/masm/Planetas/nuevosplanetas.jpg
a. Star/Solar System Birth Date • Very long ago planets would not contain enough heavy elements. • We need to have elements past the first generation star level for living things. (need supernova for fusion of elements heavier than iron) http://www.atomicarchive.com/Fusion/Images/fusion.jpg
b. Age of our Sun • The Sun needs to be in a stable burning phase (main sequence) for constant radiation and luminosity (heat and energy source). http://helios.augustana.edu/~lc/sunxray.gif http://www.highwaygirl.com/hwg/images/star.jpg http://www.pd.astro.it/education/PlanetV/planetarium/icons/EQUI.GIF
II.Earth Characteristics http://www.d21c.com/AAALynx/CB/pl/earth.jpg
a. The Earth lies within the habitable zone of the Sun. Habitable Zone (HZ): The distance from the star where the average temperature of the planet allows liquid water to exist. http://www.mallorcaweb.net/masm/Planetas/nuevosplanetas.jpg
Right Distance From Parent Star • Too great= too cool for stable water cycle • Too close= too hot for stable water cycle • This is the main aspect of Habitable Zone • Also, most life needs 0-100 Degrees Celsius http://ag.arizona.edu/extension/riparian/images/ch3_hydro-cycle.jpg
b. Right Mass/Gravity of the Planet.- Without the right mass/gravity, the atmosphere which surrounds us would move into space as well as us or we wouldn’t be able to breathe. - This also allowed the Iron Catastrophe to occur which allowed the earths’ inner layers to form. http://static.howstuffworks.com/gif/hot-air-balloon-atmosphere.jpg http://teachertech.rice.edu/Participants/louviere/Images/profile.gif
c. Right Carbon Dioxide and Water Vapor Levels in the Atmosphere • If greater amounts= runaway greenhouse effect (warming of the earth). • If lesser amounts= insufficient greenhouse effect (cooling of the earth). http://www.n-ergise.net/cnt/txt/40/1/greenhouse_effect.gif
d. Right Ozone Level in Atmosphere • If greater amounts of ozone= surface temperatures too low. • If less amounts of ozone= surface temperatures too high and too much UV radiation at surface. http://www.epcc.pref.osaka.jp/apec/eng/earth/ozone_layer_depletion/image/zu_g01.gif
e. Right Thickness of Crust • If Thicker= More oxygen in crust. • If Thinner= More volcanic and tectonic plate activity. http://www.pacificislandtravel.com/nature_gallery/volcanoes2.gif http://geography.sierra.cc.ca.us/Booth/Physical/chp13_earth/crust_composition.gif
Seismic Activity • Greater= destruction of life forms • Less= nutrients on ocean floors (from river runoff) would not be recycled by tectonic uplift. http://rst.gsfc.nasa.gov/Sect2/platespread.jpg
f. Right Internal Earth Layers – Convection currents in the outer core produce the “Magnetic Field” surrounding the earth. This provides protection from hard stellar radiation (ex. Solar Wind ) for us as well as keeping the atmosphere from being swept away. http://www.instituteforinquiry.org/inquiries/graphics/electrostorm.jpg
g. Right Rotation Period • If days (rotation period) were longer the diurnal temperature differences would be too great (temperature between night and day). • If days were shorter, atmospheric wind speed would be too great. (due to pressure differences caused by different temperature air masses) http://www.physicalgeography.net/fundamentals/images/heatingwind.GIF http://old.grotte-de-han.be/expo/effetserre.jpg
h. Right Gravitational Interaction with the Moon Affects climate and weather patterns due to influencing the earth’s spin as well as reduces the wobbling motion of the Earth. http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/Tidal%20power%20files/image002.jpg
i. Right Axial Tilt • If too much greater - the surface temperature differences would be too great. Ice and water vapor would travel to the poles, no water anywhere else. • If much less - the habitable zone would shrink in size (think narrow band around equator) • The tilt also allows the seasons to occur. http://www.learner.org/jnorth/images/imageshtml/earth-tilt.gif
Think About This…… • In 1999 Hubble space telescope indicated 125 billion galaxies. • Times that by a factor of 8 =1 trillion (1012) galaxies • There are approximately 100 billion stars per galaxy (1011) • (1011) stars x (1012) galaxies = 1023 stars in the universe
Probability • If we consider (on average) a 1% chance of each of the previously mentioned factors occurring favorable to life, that is…. • One chance in 1040 • Compared to “only” 1022 stars in the Universe • Therefore… we have a pretty unique home