Atmosphere of Venus, Mars and Earth - os 2009 Asian Science Camp August 3
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Atmosphere of Venus,
Venus Mars and Earth
Yoshihide
os de Kozai
oa
2009 Asian Science Camp
August 3The 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 D it off iinterstellar Density t t ll Matter is high.
Chemical Composition of Atmosphere
• Ch i l composition
Chemical iti off atmosphere(%)
t h (%)
• N2 O2 CO2 H 2O H2 He
• Venus 3.434 0 007
0.007 96 0 019
0.019
• 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
E th 1 20˚C 1 00
1.00
• Mars 0.006 ‐60˚C 1.52Greenhouse Effect
High temperature of Venus is caused by
ggreenhouse effect due to thick atmosphere.
p
When the sky is very clear (without clouds and
greenhouse gases)
gases), the temperature comes
down because of no blanket against infrared
radiation from
f the
h surface.
f
Carbon dioxide makes a greenhouse and if its
abundance is much lower, the mean
temperature of the earth should be lower
lower.Greenhouse effect
SUN
Infrared radiation is
absorbed/scattered in the atmosphere.
p
Cloud Cloud
l d
CO2 CO2
CO2 H2 O Vi ibl
Visible
H2 O Light
Infrared
Light
g
SurfaceMars Earth Venus
Comparison of the Atmospheres
• Venus Thick CO2 Strong Greenhouse
– 460 ˚C >> 50˚C ((no greenhouse)
g )
– Water unstable
• Mars
M V thi
Very thin CO2 Very
V weakk G
Greenhous
h
– ‐ 60˚C
– Water frozen
• Earth N2‐O2 little CO2 Moderate
Greenhouse
– 20˚C > 5˚C (no greenhouse)
– Water stable = OceanEvolution of the atmosphere:
How the Earth decreased CO2 ?
• Carbon dioxide (CO2) was first absorbed by huge
sea covering the earth
earth.
• In the sea, several plants were born and by their
photosynthesis effect the plants absorbed
carbon
ca bo dioxide
d o de and
a d made
ade oxygen
o yge (O2) .Photosynthesis
Organic mattersStromatolite
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 i especially
i ll cyanobacteria
b t i ((commonly l kknown as bl
blue-green
algae). They include some of the most ancient records of life on Earth.Fossile Stromatolite
Microfossils 3.5x109 yr before present
(Australia) that resemble filamentous
cyanobacteriaIncrease in oxygen
• In the sea
sea, chlorophyta produced oxygen by
photosynthesis and oxygen amount increased to be
1/100 of the present.
present Then,
Then multicellular organism
appeared on the Earth. It was 800 million years ago
that crustacean and mollusk appeared,
appeared when oxygen
amount was 1/10 of the present. Accordingly ozone
(from three oxygen atoms) started increasing and the
ozone layer in the upper atmosphere stopped solar
UV and XX‐ray,
ray which are poisonous for the life.
life
Formation of the ozone layer promote the life on the
land.
landChlorophyta
multicellular organism
crustacean molluskGlobal 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.
pOil Field Coral Reef
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 low‐
elevation islands.
• Japan is now in “temperature” zone. As proceeds
the gglobal warming,g, Japan
p will enter “subtropical”
p
zone with hotter and more humid climate.Light pollution
• Astronomical observation is strongly affected by
g p
“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
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 ggreater than the least
necessary illumination for lands.
• Light Environment Ordinance
(Outdoor Lighting Ordinance)
In order to decrease light
g p pollution,, Bisei‐town,,
Takayama‐village, Hamamatsu‐city, Tucson‐city
(US) enacted “Light
Light Environment Ordinance”.
Ordinance . For
example, streetlights should be covered not to
emit light upward to the sky.
sky This would also
decrease the power consumption.Earth at night from a Satellite
Habitable planet (habitable zone)
Li id water
Liquid t iis stable
t bl on th
the surface
f off a planet.
l tFactors controlling “habitability”
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
habitable.
River delta
Sedimentary rocksWhy was Mars habitable ?
• Thick CO2 atmosphere 4.0 billion yr ago.
• (3
(3‐5
5 atm. PCO2)
• Strong greenhouse effect.
• Thick atmosphere ‐‐ escaped ?You can also read
