Atmosphere of Venus, Mars and Earth Yoshihide Kozai oa 2009 Asian Science Camp August 3
The Earth from the Moon
Venus
Mars
Jupiter
Orion Nebula Where stars are born Distance 1500light Years 50 light year Wide(3 million AU) Stars are born where Density of interstellar t Matter is high.
Chemical Composition of Atmosphere Chemical composition of atmosphere(%) N 2 O 2 CO 2 H 2 O H 2 He Venus 34 3.4 0.007007 96 0.019019 Earth 78 21 0.037 1~2.8 Mars 2.7 0.13 95 0.03 Jupiter 89 11 Surface pressure Temperature Solar distance Venus 90 atm. 460 C 0.72 AU Earth 1 20 C 100 1.00 Mars 0.006 60 C 1.52
Greenhouse Effect High temperature of Venus is caused by greenhouse effect due to thick atmosphere. When the sky is very clear (without clouds and greenhouse gases), thetemperature temperature comes down because of no blanket against infrared radiation from the surface. Carbon dioxide makes a greenhouse and if its abundance is much lower, the mean temperature of theearthearth should be lower.
Greenhouse effect Infrared radiation is absorbed/scattered in the atmosphere. SUN Cloud CO 2 Infrared Light Cloud CO CO 2 2 H H 2 O 2 O Visible ibl Light Surface
Mars Earth Venus
Comparison of the Atmospheres Venus Thick CO 2 Strong Greenhouse 460 C >> 50 C (no greenhouse) Water unstable Mars Very thin CO 2 Very weak Greenhous 60 C Water frozen Earth N 2 O 2 little CO 2 Moderate Greenhouse 20 C > 5 C (no greenhouse) Water stable = Ocean
Evolution of the atmosphere: How the Earth decreased CO 2? Carbon dioxide (CO 2 ) was first absorbed by huge sea covering the earth. In the sea, several plants were born and by their photosynthesis effect the plants absorbed carbon dioxide do deand made oxygen oyge (O 2 ).
Photosynthesis Organic matters
Stromatolite Modern stromatolites in Shark Bay, Western Australia Stromatolites are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, i especially cyanobacteria (commonly known as blue-green algae). They include some of the most ancient records of life on Earth.
Fossile Stromatolite Microfossils 3.5x10 9 yr before present (Australia) that resemble filamentous cyanobacteria
Increase in oxygen In the sea, chlorophyta produced oxygen by photosynthesis and oxygen amount increased to be 1/100 of the present. Then, multicellular organism appeared on the Earth. It was 800 million years ago that crustacean and mollusk appeared, when oxygen amount was 1/10 of the present. Accordingly ozone (fromthree oxygen atoms) started increasing and the ozone layer in the upper atmosphere stopped solar UV and X ray, which are poisonous for the life. Formation of the ozone layer promote the life on the land.
Chlorophyta multicellular organism crustacean mollusk
Global Warming Organic materials containing carbon produced by photosynthesis were stored underground; oil was produced from organic materials. Coral reefs formation in the ocean capture carbon dioxide. (Limestone is composed of fossils of coral.) In recent 300 years as industrial activity has been very active by using oil and coral. Then much carbon dioxide was again produced. In the recent 50 years or so, global warming has become a serious problem.
Coral Reef Oil Field
Global Warming Increase in carbon dioxide in the atmosphere enhanced the greenhouse effect that delays the escape of energy obtained from solar radiation. That results in the global temperature increase, i.e., global warming. Melting of glaciers by the global warming should raise the sea level, which would be fatal for lowelevation islands. Japan is now in temperature zone. As proceeds the global warming, Japan will enter subtropical zone with hotter and more humid climate.
Light pollution Astronomical observation is strongly affected by light pollution, excessive obtrusive artificial lights. Especially in and around the large city, artificial lights brighten the night sky and prevent star observation. Under the sky glow of artificial lights which affect long exposure photographing, it is very difficult to observe dark stars. From the beginning of 20th century, astronomical observatories moved from cities to remote places with dark sky.
Dark sky Light pollution
Looking down the night earth from the space, we realize too much light have escaped to the sky. This amount is much greater than the least necessary illumination for lands. Light Environment Ordinance (Outdoor Lighting Ordinance) In order to decrease light pollution, Bisei town, Takayama village, Hamamatsu city, Tucson city (US) enacted Light EnvironmentOrdinance. For example, streetlights should be covered not to emit light upward to the sky. This would also decrease the power consumption.
Earth at night from a Satellite
Habitable planet (habitable zone) Liquid id water is stable on the surface of a planet.
Factors controlling habitability Distance from the sun (main star). Atmosphere (Greenhouse effect). Gravity Too small planets do not have atmosphere. Composition (presence of water). Luminosity of the sun (main star).
Mars was habitable. River delta Sedimentary rocks
Why was Mars habitable? Thick CO 2 atmosphere 4.0 billion yr ago. (3 5 atm. P CO2 ) Strong greenhouse effect. Thick atmosphere escaped?