Chapter 28
Venus
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Venus – not so twinlike after all!
Roman: Goddess of love and our
twin sister
This is the second planet from
the Sun
Mostly known as our
twin sister
But only in Size,
Density, escape velocity
& surface gravity only.
Venus – not so twinlike after all!
Roman: Goddess of love and our
twin sister
Brightest of all the
planets in the night
sky from earth.
Venus is often
termed the
“Morning Star” and
the “Evening Star.”
8000 miles
Venus – not so twinlike after all!
7950 miles
• Venus is only slightly
smaller than the Earth
(about 0.95%), but
Venus is only slightly smaller than
the Earth (about 0.95%),
Venus – not so twinlike after all!
• Venus is only slightly
smaller than the Earth
(about 0.95%), but that is
where the resemblance
stops!
– Thick clouds
completely
obscure the
surface
Venus – not so twinlike after all!
– The surface is
tremendously hot!
– ~896º Fahrenheit
– ~480º Celsius
– ~718 Kelvin
Rotation of Venus
• Of all the planets,
Venus spins about its
axis the slowest
– 243 days to
complete one
rotation
Rotation of Venus
• Of all the planets, Venus spins
about its axis the slowest
– 243 days to complete
one rotation
– Slow rotation creates
almost no magnetic
field!
https://www.youtube.com/watch?v=AgnbAcT4iMk
Rotation of Venus
• This retrograde
rotation cannot
be produced by
tidal braking
– Perhaps a
collision early
in its history
tipped its axis
Rotation of Venus
• Venus
Revolution is
224.70 days
(225 days)
– MEANS: a year
is shorter than
a day
The Venusian Atmosphere
• The atmosphere of Venus is very
different from Earth’s:
– 100 times more thicker
– Surface pressure is 90
atmospheres!
– 96.5% carbon dioxide
The Venusian Atmosphere
• The atmosphere of Venus is very
different from Earth’s:
– Thick clouds of sulfuric acid (H2SO4)
– Trace amounts of water vapor & N2
The Venusian Atmosphere
• The planet probably
underwent a runaway
greenhouse effect
• The planet has a
yellowish sky.
The Venusian Atmosphere
The Venusian Atmosphere
• Lightning storms have been spotted on Venus
• Scientist estimate that there is 100,000,000 volts of electricity
in a lightning bolt on Venus
– THEY never touch the ground!!!!
Interesting features of the surface of
Venus
•Venus has enormous
upside-down vortices
spinning over both poles of
the planet.
•Unlike Earth-based
tornadoes and hurricanes,
which suck upward, these
vortices recycle the
atmosphere downward.
•Furthermore, the north
pole of Venus has not one
but two of these vortices!
Images from Venus
• The Russian Venera spacecraft have visited the surface of
Venus
– Surface temperatures of ~718K, hot enough to melt lead!
– Discovered volcanic rocks
Images from Venus
• The spacecraft only lasted about an hour due to the
extreme temperatures and pressure
• More recent spacecraft have mapped the surface of
Venus from orbit
The Surface of Venus
• Venus has both highlands and lowlands
The Surface of Venus
• Surface features are named for prominent women in history and
mythology
The Surface of Venus
• Venus is less mountainous than Earth, with more rolling plains
The Surface of Venus
• Volcanic peaks are present in the highlands
The Surface of Venus
• Volcanic peaks are present in the highlands
Recent radar map of Venus
• The surface of Venus
seems to be relatively
young
• Not sure is volcanic
activity resurfaces the
planet rapidly or not.
• No Volcano has been
actually detected
erupting but,,,
Recent radar map of Venus
• Evidence in 2010 did
show in the clouds a
“white” spot” which
is believed to be
caused by a volcano
erupting.
• There are a few
impact craters, due
both to the thick
atmosphere and
perhaps volcanic
activity.
Interesting features of the surface of
Venus
Recent radar map of Venus
• Diameter
– 7,530 miles; 12048
Km
– 0.95 than earth
• Composition:
– Solid Fe, Ni core
like earth’s
– Magnetic field does
not exist due to
retrograde rotation.
– Mantle may contain
hotspots but not sure
Recent radar map of Venus
• Tilt of 3 degree
• Incline plane of 3.4
degrees
• Average Distance
from Sun
– .723 AU (.7 AU)
– 67,000,000 miles
67,239,000
Venus