Transcript Venus

Venus
The Second Planet
• Earth’s “sister planet”, is slightly smaller and has similar
composition.
• A collision to the early Venus causes it to rotate in the
opposite direction of other planets.
• Tidal friction has slowed Venus to have one Venusian day
almost equal to the year.
Clouds
• Like Earth, Venus is terrestrial with an atmosphere.
• Clouds on Venus block its surface from view.
– High albedo: Venus (0.65), Earth (0.37)
Orbital Craft
• In 1990-94 Magellan
orbited Venus.
– Radar measurement
– Atmosphere measures
during deorbit
• In 2005 Venus Express
was launched.
– ESA mission
– Atmosphere probes
Penetrating the Clouds
• Radar can penetrate
clouds.
– Radio waves
– Earth and orbiters
• Spacecraft can enter the
atmosphere of Venus and
photograph the surface.
– Venera 13 (1981)
Volcanos and Lava
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Volcanos act to cool down the interior of planets.
Venus shows evidence of volcanos and lava flows.
Lava brings minerals from the mantle to the crust.
Gases include carbon dioxide, sulfur dioxide and water.
gases
lava
In the Clouds
• The clouds of Venus are
made of sulfuric acid.
– High winds
– Polar vortex
– Lightning
• Hydrogen is being lost
from water breakup.
Early Atmosphere
Venus
• Start with nitrogen, water,
carbon dioxide.
• The sun evaporated the water.
• Volcanic carbon dioxide and
sulfur dioxide and chlorine
entered the atmosphere.
• Atmospheric pressure increased
to 100 times Earth, temps to
460 ºC (860 ºF).
Earth
• Start with nitrogen, water,
carbon dioxide.
• The atmosphere rained water
into oceans.
• Ocean water absorbed volcanic
gases.
• The greenhouse effect remained
mild on Earth.
Ultraviolet Light
• Astronomers discovered that chlorine in the atmosphere of
Venus causes oxygen to break up so no ozone forms.
• Without ozone in the atmosphere, UV light comes through
and sulfuric acid clouds form on Venus.
• This discovery led to the understanding that CFCs were
causing a hole in the ozone layer on Earth!