Venus
VENUS
When and where can you see it?
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Visible up to three hours after sunset or before
sunrise.
Often called the “morning” or “evening” star.
Third brightest object in the sky.
10 times brighter than Sirius.
Can be seen in the daytime, if you know where to
look.
On a moonless night, it casts a shadow!
Why is it so bright?
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It is highly reflective! 70% of the light it
received is reflected. (Only 10% of the light
reaching the moon or Mercury is reflected.)
Physical Properties
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At its closest approach to Earth, Venus is
0.72 AU from the sun.
It’s radius is about .95 Earth radii.
It has a mass of 4.9 x 1024kg or 0.82 Earth
mass.
Spacecraft visits
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1975: Soviet’s Venera 9 and 10: landed
on Venus; determined that the surface was
dry and dusty; each only lasted an hour, as
they overheated
1979: Pioneer Venus – took photographs
Temperature
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Averages 730 K (850 ˚F)
Surface Features
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Relatively smooth.
Contains two continent-sized features
(Ishtar Terra and Aphrodite Terra) contain
mountains.
Surface contains much basalt.
Volcanism and Cratering
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Contains many pancake shaped lava
domes.
Contains mostly shield volcanoes.
May still have active volcanoes, evidenced
by fluctuations in the amount of sulfur
gases in the atmosphere.
Atmospheric Features
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Some of its clouds orbit the planet in only 4
Earth days, much faster than the planet
rotates.
Is 90 times more massive than Earth.
Consists mostly of carbon dioxide; also
contains sulfuric acid.
Atmosphere is so thick that it does not
allow small meteors through.
The Greenhouse Effect on Venus
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Its atmosphere is very thick – much thicker
than Earth’s.
It contains a lot of carbon dioxide, a
greenhouse gas.
Rotation Rates
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Rate of rotation: 243 days
Venus experiences retrograde rotation.
That is, the sun rises in the west and sets
in the east.
Why does it rotate backwards?
Early in its formation, it was struck by a
large object.
Rate of revolution: 225 days