Download Venus

Planet Venus
In Roman mythology,
“Venus” was the goddess of love and fertility.
Venus was the equivalent
of the Greek goddess, “Aphrodite”.
Venus
was the consort of Vulcan…
…and Vulcan
was the god of fire.
The word “volcano”
comes from the word “Vulcan”.
Here we see Venus
locked in an embrace with Vulcan.
The Roman people
are believed to descend from them.
For centuries,
she has been called the “goddess of love”.
And in addition to that,
she also goes by 2 other nicknames.
Venus is sometimes referred to
as the morning or evening star.
Under favorable conditions,
Venus is so bright…
…that it can even
cast a shadow on Earth.
After the Moon,
Venus is the brightest object in the sky.
Venus
star
Notice how bright Venus is,
when compared with a nearby star.
Venus also has
a third nickname.
It is often referred to
as “Earth’s sister planet”.
100%
95%
At 95% the diameter of Earth,
the 2 planets are nearly the same size.
100%
95%
Venus also has
82% the mass of the Earth.
A History of Venus
Complicated history; still poorly understood.
Very similar to Earth in mass, size, composition, density,
but no magnetic field  Core solid?
 Solar wind interacts
directly with the
atmosphere, forming a bow
shock and a long ion tail.
CO2 produced during
outgassing remained in
atmosphere (on Earth:
dissolved in water).
Any water present on the
surface rapidly evaporated →
feedback through enhancement
of greenhouse effect
Heat transport from core mainly through magma flows
close to the surface ( coronae, pancake domes, etc.)
Venus is only the second planet
in order of planets away from the Sun.
Most of the time,
Venus is our closest neighbor in space.
1 AU
The average distance
from the Earth to the Sun is 1 AU.
0.72 AU
However, Venus’ average distance
is only 0.72 AUs from the Sun.
1.00
AU
_______
= 1.39 x closer
0.72 AU
0.72 AU
This makes Venus
1.39x closer to the Sun than the Earth.
(1.39)2 = 1.93 x bigger
0.72 AU
In being 1.39x closer to the Sun,
the Sun appears to be 1.93x bigger.
The Sun as seen
from Earth
This is how big the Sun appears
when viewed from Earth.
The Sun as seen
from Earth
The Sun as seen
from Venus
1.93 x bigger
And here’s how big the Sun appears
when viewed from Venus.
When Venus and the Earth
are both on the same side of the Sun…
…then Venus
is the Earth’s closest neighbor in space.
1.00 AUs – 0.72 AUs = 0.28 AUs
0.28 AUs
At this location,
Venus is only 0.28 AUs from Earth.
However, when Venus
is on the opposite side of the Earth…
…then Venus is no longer
the closest planet to the Earth.
At this location,
Venus lies 1.72 AUs from the Earth.
1.00 AUs + 0.72 AUs = 1.72 AUs
0.72 AUs
1.00 AUs
At this location,
Venus lies 1.72 AUs from the Earth.
greatest elongation
(aphelion)
When at its
greatest elongation…
greatest elongation
(aphelion)
47o
Venus is never found
more than 47o away from the Sun.
least elongation
(perihelion)
And when at its
least elongation…
39o
least elongation
(perihelion)
Venus is never found
more than 39o away from the Sun.
No matter where
Venus is found in its orbit…
midnight
…Venus is never visible
when viewed from the Earth at midnight.
noon
Venus is also never visible
when viewed from the Earth at noon.
noon
No planets
are visible in the daytime sky…
noon
…because the Sun’s light
drowns them all out.
So at what time of the day
would Venus be visible from the Earth?
6 AM
6 PM
Only in the mornings
or in the evenings.
6 AM
6 PM
And only when Venus
is in one of these positions.
6 AM
6 PM
This is why Venus
is sometimes referred to…
6 AM
6 PM
…as the morning
or evening star.
This photo tracks Venus
over a 7 month period of time.
Notice its position in the sky
when at its greatest elongation.
greatest
elongation
Notice its position in the sky
when at its greatest elongation.
greatest
elongation
47o
setting Sun
At this location,
Venus is 47o away from the setting Sun.
Space Probes
to Venus
Venus has been visited
by a number of space probes.
On its way to Mercury in 1974,
Venus was visited by “Mariner 10”.
The next probe to visit Venus
was “Pioneer Venus” in 1978.
But the mission of Pioneer Venus
took the exploration of Venus a step further.
While Pioneer Venus itself
remained in orbit around Venus...
…the 5 smaller probes it carried
were dropped to the Venusian surface.
Each of the 5 probes landed
in a different location on Venus.
However,
only one of the probes was operational…
…by the time
they had all reached the ground.
The surviving probe
transmitted information for about an hour.
Eventually it became inoperative
due to the tremendous heat and pressure.
The Magellan space probe
was sent to Venus in 1993.
Of all the probes
sent to Venus…
…it has by far
yielded the best results.
Magellan’s main mission
was to map the surface using radar.
Information was taken in strips
then the data was radioed back to the Earth.
Most of the Venus photos you will see
came from the Magellan mission.
While the United States
concentrated only on orbiting Venus…
The Soviet Union, on the other hand,
concentrated on landing on the surface.
Their Venera 13 spacecraft
took the only photograph of its surface.
Here is the same photo
artificially adjusted for color.
The dried rock and soil
resemble dried streambeds on Earth.
Here is a close-up
of the same photo.
Part of the spacecraft’s footpad
are seen in the photograph.
Phases of
Venus
The orbit of Venus
lies entirely inside the orbit of the Earth.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
When viewed from Earth,
Venus passes through a full cycle of phases.
Since it is only visible
in the daytime sky…
…then the “Full Venus”
can never be seen from Earth.
Full Venus
…then the “Full Venus”
can never be seen from Earth.
It was this discovery…
as well as the phases of Venus…
…which convinced Galileo
that the heliocentric model was correct.
Rotation
VS
Revolution
The Rotation of Venus
• Almost all planets rotate
counterclockwise, i.e. in the
same sense as orbital motion.
• Exceptions: Venus, Uranus
and Pluto
• Venus rotates clockwise,
with period slightly longer
than orbital period.
Possible reasons:
• Off-center collision with
massive protoplanet
• Tidal forces of the sun on molten core
Revolution
Days
000.00
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
014.06
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
028.13
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
042.19
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
056.25
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
070.31
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
084.38
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
098.44
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
112.50
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
126.56
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
140.63
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
154.69
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
168.75
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
182.81
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
196.88
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
210.94
Venus orbits the Sun
with a 225-day period of revolution.
Revolution
Days
225.00
Venus orbits the Sun
with a 225-day period of revolution.
counter-clockwise
Venus revolves around the Sun
in a counter-clockwise direction.
clockwise
However, Venus is the only planet
to rotate in a clockwise direction.
This means that
noon-to-noon on Venus…
Synodic Rotation
Days
000.00
…will occur
in only 116 days.
Synodic Rotation
Days
014.50
…will occur
in only 116 days.
Synodic Rotation
Days
029.00
…will occur
in only 116 days.
Synodic Rotation
Days
043.50
…will occur
in only 116 days.
Synodic Rotation
Days
058.00
…will occur
in only 116 days.
Synodic Rotation
Days
058.00
midnight
…will occur
in only 116 days.
Synodic Rotation
Days
058.00
…will occur
in only 116 days.
Synodic Rotation
Days
072.50
…will occur
in only 116 days.
Synodic Rotation
Days
087.00
…will occur
in only 116 days.
Synodic Rotation
Days
101.50
…will occur
in only 116 days.
Synodic Rotation
Days
116.00
…will occur
in only 116 days.
Synodic Rotation
Days
116.00
noon
…will occur
in only 116 days.
noon
Even though it only takes 116 days
for Venus to experience its second noon…
noon
…it has not yet completed,
even half a rotation on its axis.
Synodic Rotation
Days
000.00
noon
Watch its
synodic rotation again.
Synodic Rotation
Days
000.00
Watch its
synodic rotation again.
Synodic Rotation
Days
014.50
Watch its
synodic rotation again.
Synodic Rotation
Days
029.00
Watch its
synodic rotation again.
Synodic Rotation
Days
043.50
Watch its
synodic rotation again.
Synodic Rotation
Days
058.00
Watch its
synodic rotation again.
Synodic Rotation
Days
058.00
midnight
Watch its
synodic rotation again.
Synodic Rotation
Days
058.00
Watch its
synodic rotation again.
Synodic Rotation
Days
072.50
Watch its
synodic rotation again.
Synodic Rotation
Days
087.00
Watch its
synodic rotation again.
Synodic Rotation
Days
101.50
Watch its
synodic rotation again.
Synodic Rotation
Days
116.00
Watch its
synodic rotation again.
Synodic Rotation
Days
116.00
noon
Watch its
synodic rotation again.
Sidereal Rotation
Days
000.00
pointing
upward
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
000.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
014.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
029.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
043.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
058.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
072.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
087.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
101.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
116.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
130.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
145.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
159.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
174.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
188.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
203.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
217.50
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
232.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
243.00
A sidereal rotation, on the other hand,
requires 243 days to complete.
Sidereal Rotation
Days
243.00
pointing
upward
A sidereal rotation, on the other hand,
requires 243 days to complete.
pointing
upward
This means that the day on Venus
is longer than Venus’ year.
Let’s watch the sidereal rotation again
and keep a tally of what we observe.
Day Counter
000.00
Sidereal
Revolution
Synodic
0
0
0
pointing
upward
Day Counter
000.00
Sidereal
Revolution
Synodic
0
0
0
Day Counter
014.50
Sidereal
Revolution
Synodic
0
0
0
Day Counter
029.00
Sidereal
Revolution
Synodic
0
0
0
Day Counter
043.50
Sidereal
Revolution
Synodic
0
0
0
Day Counter
058.00
Sidereal
Revolution
Synodic
0
0
0
Day Counter
072.50
Sidereal
Revolution
Synodic
0
0
0
Day Counter
087.00
Sidereal
Revolution
Synodic
0
0
0
Day Counter
101.50
Sidereal
Revolution
Synodic
0
0
0
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
0
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
0
noon
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
0
noon
At 116 days,
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
0
noon
At 116 days,
Venus completes one noon-to-noon.
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
0
noon
At 116 days,
Venus completes one noon-to-noon.
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
1
noon
At 116 days,
Venus completes one noon-to-noon.
Day Counter
116.00
Sidereal
Revolution
Synodic
0
0
1
Day Counter
130.50
Sidereal
Revolution
Synodic
0
0
1
Day Counter
145.00
Sidereal
Revolution
Synodic
0
0
1
Day Counter
159.50
Sidereal
Revolution
Synodic
0
0
1
Day Counter
174.00
Sidereal
Revolution
Synodic
0
0
1
Day Counter
188.50
Sidereal
Revolution
Synodic
0
0
1
Day Counter
203.00
Sidereal
Revolution
Synodic
0
0
1
Day Counter
217.50
Sidereal
Revolution
Synodic
0
0
1
Day Counter
225.00
Sidereal
Revolution
Synodic
0
0
1
Day Counter
225.00
Sidereal
Revolution
Synodic
0
0
1
At 225 days,
Day Counter
225.00
Sidereal
Revolution
Synodic
0
0
1
At 225 days,
Venus competes one revolution.
Day Counter
225.00
Sidereal
Revolution
Synodic
0
0
1
At 225 days,
Venus competes one revolution.
Day Counter
225.00
Sidereal
Revolution
Synodic
0
1
1
At 225 days,
Venus competes one revolution.
Day Counter
225.00
Sidereal
Revolution
Synodic
0
1
1
At 225 days,
Venus competes one revolution.
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
1
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
1
At 232 days,
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
1
At 232 days,
Venus competes its second noon-to-noon.
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
1
noon
At 232 days,
Venus competes its second noon-to-noon.
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
1
noon
At 232 days,
Venus competes its second noon-to-noon.
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
2
noon
At 232 days,
Venus competes its second noon-to-noon.
Day Counter
232.00
Sidereal
Revolution
Synodic
0
1
2
Day Counter
243.00
Sidereal
Revolution
Synodic
0
1
2
Day Counter
243.00
Sidereal
Revolution
Synodic
0
1
2
And finally, at 243 days,
Venus competes its first sidereal day.
Day Counter
243.00
Sidereal
Revolution
Synodic
0
1
2
And finally, at 243 days,
Venus competes its first sidereal day.
Day Counter
243.00
Sidereal
Revolution
Synodic
1
1
2
And finally, at 243 days,
Venus competes its first sidereal day.
Day Counter
243.00
Sidereal
Revolution
Synodic
1
1
2
And finally, at 243 days,
Venus competes its first sidereal day.
The rotational period of Venus
was difficult to establish for 2 reasons.
In the first place,
Venus has a slow rotation rate.
The second reason
has to do with its clouds.
thick cloud cover
The surface of Venus
is enshrouded within a thick cloud clover.
thick cloud cover
In visible light wavelengths,
it’s surface is impossible to view.
But with the help
of cloud-penetrating radar…
But with the help
of cloud-penetrating radar…
…the Venusian surface
is revealed in fine detail.
This photo is a radio image
taken by the Magellan space probe in 1993.
When false color
is added to the image…
When false color
is added to the image…
…then plateaus and lowlands
are brought into view.
North Pole
Venus
equator
rotation: clockwise
radio telescope
(satellite dish)
Just like
with Mercury…
…the Doppler Effect and radar
revealed the rotation rate on Venus.
receding side
red-shifted
approaching side
blue-shifted
red-shifted
blue-shifted
red-shifted
The fact that there was
a red and blue shift…
blue-shifted
red-shifted
…is what determined
that Venus was rotating in the first place.
blue-shifted
red-shifted
It was the amount
of red and blue shift…
blue-shifted
red-shifted
…which determined the rate
at which Venus rotated on its axis.
Planet Venus
Tilt on the Axis
23.5o
The Earth is tilted
by 23.5o on its axis.
3o
Venus, however,
is only tilted by 3o on its axis.
3o
Because it is nearly vertical,
Venus does not experience seasons.
The Surface
of Venus
Once radar from Magellan
had penetrated the thick clouds on Venus…
…its surface
was revealed in fine detail.
Magellan mapped the surface of Venus
in long strips called “noodles”.
The black lines seen in this photo
represent places where data is missing.
Approximately 90% of the Venusian surface
is relatively flat terrain (lowlands).
The remaining 10% of the surface
is elevated plateaus (highlands).
The 2 largest highlands
are Aphrodite Terra and Ishtar Terra.
Aphrodite Terra
is the larger of the two.
It stretches
halfway around the equator.
Ishtar Terra
is found in the North.
It contains
the Maxwell Mountain Range.
Lakshmi Planum and Maxwell Mountains
Radar image
Wrinkled mountain formations indicate compression
and wrinkling, though there is no evidence of plate
tectonics on Venus.
The surface of Venus
contains thousands of active volcanoes.
Shield Volcanoes
Found above
hot spots:
Fluid magma
chamber, from
which lava erupts
repeatedly through
surface layers
above.
All volcanoes on Venus and Mars are shield volcanoes
Shield Volcanoes (2)
Tectonic plates moving over hot spots producing
shield volcanoes  Chains of volcanoes
Example: The
Hawaiian Islands
At 8 km in elevation
Maat Mons is the highest in elevation.
Gula Mons
is about 3 km in elevation.
The 3-D perspective shown here
was vertically exaggerated by computers.
Shown in this photo
are the “pancake dome” volcanoes.
They are characterized
by flat tops and steep sides.
The lava forming their sides
was highly viscous and slow-flowing.
The lava hardened
before it had a chance to spread out.
Evidence of lava flows
can be seen everywhere on Venus.
The lava from this volcano
flowed for hundreds of kilometers.
Also notice the large impact crater
shown in the center of the photo.
Volcanism on Venus
Sapas Mons (radar image)
~ 400 km (250 miles)
2 lava-filled calderas
Lava flows
Volcanic Features on Venus
Baltis Vallis: 6800 km long
lava flow channel (longest
in the solar system!)
Some lava flows collapsed
after molten lava drained away
Aine
Corona
Coronae: Circular bulges formed by
volcanic activity
Pancake
Domes:
Associated
with volcanic
activity forming
coronae
Venus only has 10-20%
as many impact craters as the lunar maria.
This suggests a surface age
of less than 1 billion years old.
Many of the smaller meteorites
burn up in the thick atmosphere.
The circles shown on this map
plot the locations of impact craters.
Since the craters
are evenly distributed…
…then the surface of Venus
must all be the same age.
While there is no evidence
of plate tectonics on Venus…
…this photo shows a feature
known as “Rift Valley”.
The Interior
of Venus
There is much debate and disagreement
about the internal structure of Venus.
rocky
crust
metallic
core
viscous
mantle
But just like the other planets,
Venus certainly has the same 3 layers.
Venus
Venus has a very weak magnetic field.
(About 25,000 times weaker than Earth’s)
Venus appears to lack the necessary
ingredients to generate a magnetic
field
(no liquid core?)
rocky
crust
metallic
core
viscous
mantle
With no detectable magnetic field
the core is believed to be solid.
Surface
Temperature
The surface temperature on Venus
is a smoldering 800o F.
This means that Venus is 800o F
all day, all night, all year long.
One place on Venus
is as hot as any other place on Venus.
If oceans had ever existed
in the distant past…
…they have long since boiled away
in all of this unimaginable heat.
With virtually no tilt
on its axis…
…all 4 seasons
share the exact same climate.
Like ceramic pottery
baking in a hot kiln oven…
…the surface rocks on Venus
slowly cook in the searing heat.
At only 90o F, however,
the clouds of Venus are quite a bit cooler.
Sulfur and water vapor
combine to form clouds of sulfuric acid.
Sulfuric acid is also the type of acid
found in car batteries.
The clouds are continually re-supplied
with sulfur from active volcanoes.
But even though sulfuric acid
rains down from the clouds on Venus...
…those raindrops evaporate
before ever reaching the ground.
Even more inhospitable
are the electrical storms on Venus.
Both day and night alike,
electricity rains down from its skies.
Imagine the dangers
of trying to land a spacecraft on Venus.
If the heat and electricity
didn’t kill the crew…
…then they would be crushed to death
by the thick atmospheric pressure.
…then they would be crushed to death
by the thick atmospheric pressure.
The atmospheric pressure on Venus
is 100X thicker than the Earth’s.
15 lbs. / in2
Since the atmospheric pressure on Earth
is about 15 lbs/in2 at sea level…
15 lbs. / in2
1500 lbs. / in2
…then the atmospheric pressure on Venus
is about 1500 lbs/in2.
Composition
of Venus’ Atmosphere
____________________________
carbon dioxide = 96.5 %
nitrogen = 3.5 %
The atmosphere of Venus
is composed largely of just 2 gases.
Composition
of Venus’ Atmosphere
____________________________
carbon dioxide = 96.5 %
nitrogen = 3.5 %
With an atmosphere
consisting mostly carbon dioxide…
Composition
of Venus’ Atmosphere
____________________________
carbon dioxide = 96.5 %
nitrogen =
3.5 %
…Venus experiences
a runaway greenhouse effect.
The Runaway
Greenhouse Effect
The main reason
why Venus is so bright…
70% reflected
back into space
…is because its white clouds
reflect 70% of the sunlight striking them.
70% reflected
back into space
Venus’ albedo = 0.7
albedo – the reflectivity of a surface.
This makes
for a very bright planet.
70% reflected
back into space
Below the clouds,
the air is clear.
70% reflected
back into space
The remaining sunlight
trickles through the thick cloud cover.
70% reflected
back into space
Sunlight cannot shine directly
onto the Venusian surface…
70% reflected
back into space
diffuse
visible light
…because the clouds serve as a filter,
making the light “diffuse”.
70% reflected
back into space
diffuse
visible light
This kind of light
does not cast shadows.
70% reflected
back into space
diffuse
visible light
Upon reaching the ground
the visible light is absorbed by the surface.
70% reflected
back into space
diffuse
visible light
infrared
The waves are then re-emitted
at the longer wavelength of infrared.
70% reflected
back into space
diffuse
visible light
trapped by CO2,
H2O vapor, and clouds
infrared
Like a greenhouse,
the heat is trapped and cannot escape.
70% reflected
back into space
diffuse
visible light
trapped by CO2,
H2O vapor, and clouds
infrared
Venus is not receiving, however,
more energy than it emits back into space.
70% reflected
back into space
diffuse
visible light
escaping
energy
trapped by CO2,
H2O vapor, and clouds
infrared
Some energy
must escape back into space.
70% reflected
back into space
diffuse
visible light
trapped by CO2,
H2O vapor, and clouds
infrared
The amount of energy
coming in from the Sun…
escaping
energy
70% reflected
back into space
diffuse
visible light
energy in = energy out
escaping
energy
trapped by CO2,
H2O vapor, and clouds
infrared
…must equal the amount of energy
that escapes back into space.
70% reflected
back into space
diffuse
visible light
energy in = energy out
trapped by CO2,
H2O vapor, and clouds
infrared
If this were not the case,
then Venus would explode.
escaping
energy
70% reflected
back into space
diffuse
visible light
energy in = energy out
escaping
energy
trapped by CO2,
H2O vapor, and clouds
infrared
Every single day,
its temperature would have climbed higher.
70% reflected
back into space
diffuse
visible light
energy in = energy out
escaping
energy
trapped by CO2,
H2O vapor, and clouds
infrared
After 4 billions of years of this,
its temperature would be in the trillionso F.
Venus Statistics
Venus
Mass (kg) 4.869e+24
Mass (Earth = 1) .81476
Equatorial radius (km) 6,051.8
Equatorial radius (Earth = 1) .94886
Mean density (gm/cm^3) 5.25
Mean distance from the Sun (km) 108,200,000
Mean distance from the Sun (Earth = 1) 0.7233
Rotational period (days) -243.0187
Orbital period (days) 224.701
Mean orbital velocity (km/sec) 35.02
Orbital eccentricity 0.0068
Tilt of axis (degrees) 177.36
Orbital inclination (degrees) 3.394
Equatorial surface gravity (m/sec^2) 8.87
Equatorial escape velocity (km/sec) 10.36
Visual geometric albedo 0.65
Magnitude (Vo) -4.4
Mean surface temperature 482°C
Atmospheric pressure (bars) 92
Atmospheric composition
Carbon dioxide 96%
Nitrogen 3+%
Trace amounts of: Sulfur dioxide, water vapor,
carbon monoxide, argon, helium, neon,
hydrogen chloride, and hydrogen fluoride.