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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 toas “Earth’s sister planet”.
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.
100% 95%
A History of VenusComplicated history; still poorly understood.
Very similar to Earth in mass, size, composition, density, but no magnetic field Core solid?
Solar wind interacts Solar wind interacts directly with the directly with the atmosphere, forming a bow atmosphere, forming a bow shock and a long ion tail. shock and a long ion tail.
COCO22 produced during produced during
outgassing remained in outgassing remained in atmosphere (on Earth: atmosphere (on Earth: dissolved in water).dissolved in water).
Heat transport from core mainly through magma flows close to the surface ( coronae, pancake domes, etc.)
Any water present on the Any water present on the surface rapidly evaporated surface rapidly evaporated → → feedback through enhancement feedback through enhancement of greenhouse effectof greenhouse effect
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.
The average distance from the Earth to the Sun is 1 AU.
1 AU
0.72 AU
However, Venus’ average distance is only 0.72 AUs from the Sun.
_______1.00 AU
0.72 AU= 1.39 x closer
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.
This is how big the Sun appears when viewed from Earth.
The Sun as seen 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.
At this location, Venus is only 0.28 AUs from Earth.
1.00 AUs – 0.72 AUs = 0.28 AUs
0.28 AUs
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 AUs0.72 AUs
1.00 AUs + 0.72 AUs = 1.72 AUs
At this location, Venus lies 1.72 AUs from the Earth.
When at its greatest elongation…
greatest elongation (aphelion)
47o
Venus is never found more than 47o
away from the Sun.
greatest elongation (aphelion)
least elongation (perihelion)
And when at its least elongation…
Venus is never found more than 39o
away from the Sun.
39o
least elongation (perihelion)
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.
Notice its position in the sky when at its greatest
elongation.
greatest elongation
setting Sun
47o
greatest elongation
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
RevolutionDays
000.00
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
014.06
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
028.13
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
042.19
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
056.25
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
070.31
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
084.38
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
098.44
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
112.50
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
126.56
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
140.63
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
154.69
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
168.75
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
182.81
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
196.88
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
210.94
Venus orbits the Sun with a 225-day period of revolution.
RevolutionDays
225.00
Venus orbits the Sun with a 225-day period of revolution.
Venus revolves around the Sun in a counter-clockwise direction.
counter-clockwise
However, Venus is the only planet to rotate in a clockwise direction.
clockwise
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
…will occur in only 116 days.
midnight
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
…will occur in only 116 days.
noon
Even though it only takes 116 days for Venus to experience its second
noon…
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
116.00noon
Watch its synodic rotation again.
Days
000.00
pointing upward
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
000.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
014.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
029.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
043.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
058.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
072.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
087.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
101.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
116.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
130.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
145.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
159.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
174.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
188.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
203.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
217.50
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
232.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
243.00
Sidereal Rotation
A sidereal rotation, on the other hand, requires 243 days to
complete.
Days
243.00
Sidereal Rotation
pointing upward
A sidereal rotation, on the other hand, requires 243 days to
complete.
This means that the day on Venus is longer than Venus’ year.
pointing upward
Let’s watch the sidereal rotation again and keep a tally of what we observe.
000.00Day Counter
0
00
Sidereal
Revolution
Synodic
pointing upward
000.00Day Counter
0
00
Sidereal
Revolution
Synodic
014.50Day Counter
0
00
Sidereal
Revolution
Synodic
029.00Day Counter
0
00
Sidereal
Revolution
Synodic
043.50Day Counter
0
00
Sidereal
Revolution
Synodic
058.00Day Counter
0
00
Sidereal
Revolution
Synodic
072.50Day Counter
0
00
Sidereal
Revolution
Synodic
087.00Day Counter
0
00
Sidereal
Revolution
Synodic
101.50Day Counter
0
00
Sidereal
Revolution
Synodic
116.00Day Counter
0
00
Sidereal
Revolution
Synodic
116.00Day Counter
0
00
Sidereal
Revolution
Synodic
noon
At 116 days,
116.00Day Counter
0
00
Sidereal
Revolution
Synodic
noon
At 116 days, Venus completes one noon-to-noon.
116.00Day Counter
0
00
Sidereal
Revolution
Synodic
noon
At 116 days, Venus completes one noon-to-noon.
116.00Day Counter
0
00
Sidereal
Revolution
Synodic
noon
At 116 days, Venus completes one noon-to-noon.
116.00Day Counter
1
00
Sidereal
Revolution
Synodic
noon
116.00Day Counter
1
00
Sidereal
Revolution
Synodic
130.50Day Counter
1
00
Sidereal
Revolution
Synodic
145.00Day Counter
1
00
Sidereal
Revolution
Synodic
159.50Day Counter
1
00
Sidereal
Revolution
Synodic
174.00Day Counter
1
00
Sidereal
Revolution
Synodic
188.50Day Counter
1
00
Sidereal
Revolution
Synodic
203.00Day Counter
1
00
Sidereal
Revolution
Synodic
217.50Day Counter
1
00
Sidereal
Revolution
Synodic
225.00Day Counter
1
00
Sidereal
Revolution
Synodic
225.00Day Counter
1
00
Sidereal
Revolution
Synodic
At 225 days,
225.00Day Counter
1
00
Sidereal
Revolution
Synodic
At 225 days, Venus competes one revolution.
225.00Day Counter
1
00
Sidereal
Revolution
Synodic
At 225 days, Venus competes one revolution.
225.00Day Counter
1
01
Sidereal
Revolution
Synodic
At 225 days, Venus competes one revolution.
225.00Day Counter
1
01
Sidereal
Revolution
Synodic
At 225 days, Venus competes one revolution.
232.00Day Counter
1
01
Sidereal
Revolution
Synodic
232.00Day Counter
1
01
Sidereal
Revolution
Synodic
At 232 days,
232.00Day Counter
1
01
Sidereal
Revolution
Synodic
At 232 days, Venus competes its second noon-to-noon.
232.00Day Counter
1
01
Sidereal
Revolution
Synodic
At 232 days, Venus competes its second noon-to-noon.
noon
232.00Day Counter
1
01
Sidereal
Revolution
Synodic
noon
At 232 days, Venus competes its second noon-to-noon.
232.00Day Counter
2
01
Sidereal
Revolution
Synodic
noon
At 232 days, Venus competes its second noon-to-noon.
232.00Day Counter
2
01
Sidereal
Revolution
Synodic
243.00Day Counter
2
01
Sidereal
Revolution
Synodic
243.00Day Counter
2
01
Sidereal
Revolution
Synodic
And finally, at 243 days, Venus competes its first sidereal
day.
243.00Day Counter
2
01
Sidereal
Revolution
Synodic
And finally, at 243 days, Venus competes its first sidereal
day.
243.00Day Counter
2
11
Sidereal
Revolution
Synodic
And finally, at 243 days, Venus competes its first sidereal
day.
243.00Day Counter
2
11
Sidereal
Revolution
Synodic
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.
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.
thick cloud cover
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
equator
Venus
rotation: clockwise
radio telescope(satellite dish)
Just like with Mercury…
…the Doppler Effect and radar revealed the rotation rate on Venus.
red-shifted
receding side
red-shifted
blue-shifted
approaching side
red-shifted
blue-shifted
The fact that there was a red and blue shift…
red-shifted
blue-shifted
…is what determined that Venus was rotating in the first place.
red-shifted
blue-shifted
It was the amount of red and blue shift…
red-shifted
blue-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.
Venus, however, is only tilted by 3o on its axis.
3o
Because it is nearly vertical, Venus does not experience
seasons.
3o
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)
2 lava-filled calderas~ 400 km (250 miles)
Lava flows
Volcanic Features on Venus
Baltis Vallis: 6800 km long lava flow channel (longest
in the solar system!) Coronae: Circular bulges formed by volcanic activity
Aine Corona
Pancake Domes:
Associated with volcanic
activity forming coronae
Some lava flows collapsed after molten lava drained away
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 appears to lack the necessary ingredients to generate a magnetic
field
(no liquid core?)
Venus has a very weak magnetic field.
(About 25,000 times weaker than Earth’s)
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 Fall 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…
1500 lbs. / in2
…then the atmospheric pressure on Venus is about 1500 lbs/in2.
15 lbs. / in2
Composition of Venus’ Atmosphere
The atmosphere of Venus is composed largely of just 2 gases.
carbon dioxidenitrogen 3.5 %
96.5 %==
____________________________
Composition of Venus’ Atmosphere
With an atmosphere consisting mostly carbon dioxide…
carbon dioxidenitrogen 3.5 %
96.5 %==
____________________________
Composition of Venus’ Atmosphere
…Venus experiences a runaway
greenhouse effect.
carbon dioxide
nitrogen 3.5 %
96.5 %=
=
____________________________
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
This kind of light does not cast shadows.
diffuse visible light
70% reflected back into space
Upon reaching the ground the visible light is absorbed by the surface.
diffuse visible light
70% reflected back into space
The waves are then re-emitted at the longer wavelength of infrared.
diffuse visible light
infrared
70% reflected back into space
trapped by CO2,
Like a greenhouse, the heat is trapped and cannot escape.
H2O vapor, and clouds
infrared
diffuse visible light
70% reflected back into space
trapped by CO2,
Venus is not receiving, however, more energy than it emits back
into space.
H2O vapor, and clouds
infrared
diffuse visible light
70% reflected back into space
trapped by CO2,
Some energy
H2O vapor, and clouds
must escape back into space.
infrared
diffuse visible light
escaping energy
70% reflected back into space
trapped by CO2,
The amount of energy coming in from the Sun…
H2O vapor, and clouds
infrared
diffuse visible light
escaping energy
70% reflected back into space
trapped by CO2, H2O vapor, and clouds
energy in = energy out
…must equal the amount of energy that escapes back into
space.
diffuse visible light
infrared
escaping energy
70% reflected back into space
trapped by CO2, H2O vapor, and clouds
energy in = energy out
If this were not the case, then Venus would explode.
infrared
diffuse visible light
escaping energy
70% reflected back into space
trapped by CO2, H2O vapor, and clouds
energy in = energy out
Every single day, its temperature would have climbed higher.
infrared
diffuse visible light
escaping energy
70% reflected back into space
trapped by CO2, H2O vapor, and clouds
energy in = energy out
After 4 billions of years of this, its temperature would be in the trillionso F.
infrared
diffuse visible light
escaping energy
VenusVenus Statistics
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.