Sleep Facts About Venus

Float into the quiet mysteries of Venus, the brilliant neighbor that graces our twilight skies. Host Benjamin Boster shares the planet’s history, atmosphere, and gentle secrets in a slow and steady tone, perfect for winding down. Let your thoughts drift through the clouds of Earth’s sister world.

Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast where I help you drift off one fact at a time.

I'm your host Benjamin Boster and if you enjoy the show please follow so you never miss an episode.

Today's episode is about the planet Venus.

Venus is the second planet from the Sun.

It is often called Earth's twin or sister among the planets of the solar system for its orbiting being the closest to Earth's,

Both being rocky planets and having the most similar and nearly equal size and mass.

Venus though differs significantly by having no liquid water and its atmosphere is far thicker and denser than that of any other rocky body in the solar system.

It is composed of mostly carbon dioxide and has a cloud layer of sulfuric acid that spans the whole planet.

At the mean surface level the atmosphere reaches a temperature of 737 Kelvin.

That's roughly 464 degrees Celsius or 867 degrees Fahrenheit.

And a pressure 92 times greater than Earth's at sea level,

Turning the lowest layer of the atmosphere into a supercritical fluid.

From Earth,

Venus is visible as a star-like point of light,

Appearing brighter than any other natural point of light in Earth's sky,

And is an inferior planet,

Always relatively close to the Sun,

Either as the brightest morning star or evening star.

The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.

6 years.

In the course of this,

Venus comes closer to Earth than any other planet.

While on average,

Mercury stays closer to Earth than any other planet due to its orbit being closer to the Sun.

For interplanetary space flights,

Venus is frequently used as a waypoint for gravity assists,

Because it offers a more economical and faster route.

Venus has no moons and has a very slow retrograde rotation about its axis,

A result of competing forces of solar tidal locking and differential heating of Venus's massive atmosphere.

As a result,

The Venusian day is 116.

75 Earth days long,

About half of a Venusian solar year,

Which is 224.

7 Earth years long.

Venus has a weak magnetosphere,

Lacking an internal dynamo that is induced by the solar wind,

Interacting with the atmosphere.

Internally,

Venus has a core,

Mantle and crust.

Internal heat escapes through active volcanism,

Resulting in resurfacing instead of plate tectonics.

Venus may have had liquid surface water early in its history with a habitable environment,

Before a runaway greenhouse effect evaporated any water and turned Venus into its present state.

Conditions at the cloud layer of Venus have been identified as possibly favorable for life on Venus,

With possible biomarkers having been found in 2020,

Which has spurred new research and mission to Venus.

Humans have observed Venus throughout history across the globe,

Acquiring particular importance in many cultures.

With telescopes,

The phases of Venus became discernible,

And by 1613 were presented as decisive evidence disproving the then-dominant geocentric model and supporting the heliocentric model.

Venus was visited for the first time in 1961 by Venera 1,

Which flew past the planet,

Achieving the first interplanetary spaceflight.

The first data from Venus were returned during the second interplanetary mission,

Mariner 2,

In 1962.

In 1967,

The first interplanetary impactor,

Venera 4,

Reached Venus,

Followed by the lander Venera 7 in 1970.

The data from these missions revealed the strong greenhouse effect of carbon dioxide in its atmosphere,

Which raised concerns about increasing carbon dioxide levels in Earth's atmosphere and their role in driving climate change.

As of 2025,

JUICE and Solar Orbiter are on their way to fly by Venus in 2025 and 2026 respectively.

And the next mission planned to launch to Venus is the Venus Lifefinder scheduled for 2026.

Venus is one of the four terrestrial planets in the solar system,

Meaning that it is a rocky body like Earth.

It is similar to Earth in size and mass,

And is often described as Earth's sister or twin.

Venus is very close to spherical due to its slow rotation.

It has a diameter of 12,

103.

6 km,

Only 638.

4 km less than Earth,

And its mass is 81.

5% of Earth's,

Making it the third smallest planet in the solar system.

Conditions on the surface of Venus differ radically from those on Earth because its dense atmosphere is 96.

5% carbon dioxide,

Causing an intense greenhouse effect,

With most of the remaining 3.

5% being nitrogen.

The surface pressure is 9.

3 MPa,

And the average surface temperature is 737 K,

Above the critical points of both major constituents,

And making the surface atmosphere a supercritical fluid of mainly supercritical carbon dioxide and some supercritical nitrogen.

The Venusian surface was a subject of speculation until some of its secrets were revealed by probes in the 20th century.

Venera landers in 1975 and 1982 returned images of a surface covered in sediment and relatively angular rocks.

The surface was mapped and detailed by Magellan in 1990 and 1991.

There is evidence of extensive volcanism,

And variations in the atmospheric sulfur dioxide may indicate that there are active volcanoes.

About 80% of the Venusian surface is covered by smooth volcanic plains,

Consisting of 70% plains with wrinkle ridges and 10% smooth or low-baked plains.

Two highland continents make up the rest of its surface area,

One lying in the planet's northern hemisphere and the other just south of the equator.

The northern continent is called Ishtar Terra after Ishtar,

The Babylonian goddess of love,

And is about the size of Australia.

The Maxwell Montes mountain range lies on Ishtar Terra.

Its peak is the highest point on Venus,

11 km above the Venusian average surface elevation.

The southern continent is called Aphrodite Terra after the Greek mythological goddess of love and is the larger of the two highland regions at roughly the size of South America.

A network of fractures and faults covers much of this area.

There is recent evidence of lava flow on Venus,

2024,

Such as flows on Sif Mons,

A shield volcano,

And on Niobe Planitia,

A flat plain.

There are visible calderas.

The planet has few impact craters.

Demonstrating that the surface is relatively young,

At 300 to 600 million years old.

Venus has some unique surface features in addition to the impact craters,

Mountains,

And valleys commonly found on rocky planets.

Among these are flat-tobbed volcanic features called fara,

Which look somewhat like pancakes and range in size from 20 to 50 km across.

And from 100 to 1000 m high.

Radial star-like fracture systems called novae features with both radial and concentric fractures resembling spider webs known as arachnoids and coronae,

Circular rings of fractures sometimes surrounded by a depression.

These features are volcanic in origin.

Most Venusian surface features are named after historical and mythological women.

Exceptions are Maxwell Montes,

Named after James Clerk Maxwell,

And highland regions Alpha Regio,

Beta Regio,

And Ovda Regio.

The last three features were named before the current system was adopted by the International Astronomical Union,

The body which oversees planetary nomenclature.

The longitude of physical features on Venus is expressed relative to its prime meridian.

The original prime meridian passed through the radar bright spot at the center of the oval feature Eve,

Located south of Alpha Regio.

After the Venera missions were completed,

The prime meridian was redefined to pass through the central peak in the crater Ariadne on Sedna Planitia.

The stratigraphically oldest Tessera terrains have consistently lower thermal emissivity than the surrounding basaltic plains measured by Venus Express and Magellan,

Indicating a different,

Possibly a more felsic mineral assemblage.

The mechanism to generate a large amount of felsic crust usually requires the presence of a water ocean and plate tectonics,

Implying that habitable condition existed on early Venus with large bodies of water at some point.

However,

The nature of Tessera terrains is far from certain.

Studies reported in 2023 suggested for the first time that Venus may have had plate tectonics during ancient times,

And as a result may have had a more habitable environment,

Possibly one capable of sustaining life.

Venus gained interest as a case for research into the development of Earth-like planets and their habitability.

Much of the Venusian surface is mapped by volcanic activity.

Venus has several times as many volcanoes as Earth,

And it has 167 large volcanoes that are over 100 km across.

The only volcanic complex of this size on Earth is the big island of Hawaii.

More than 85,

000 volcanoes on Venus have been identified and mapped.

This is not because Venus is more volcanically active than Earth,

But because its crust is older and is not subject to the erosion processes active on Earth.

Earth's oceanic crust is continually recycled by subduction at the boundaries of tectonic plates and has an average age of about 100 million years,

Which is a record.

Several lines of evidence point to ongoing volcanic activity on Venus.

Sulfur dioxide concentrations in the upper atmosphere dropped by a factor of 10 between 1978 and 1986,

Jumped in 2006,

And again declined tenfold.

This may mean that levels of sulfur dioxide and sulfur dioxide in the upper atmosphere by a factor of 5.

It has been discussed that Venusian lightning could originate from volcanic activity.

In January 2020,

Astronomers reported evidence that levels could be explained by energetic collisions when the planet was young as well as radioactive decay as in the case of the Earth.

Impacts would have had significantly higher velocity than on Earth,

Both because Venus moves faster due to its closer proximity to the Sun than on Earth.

In 2008 and 2009,

The first direct evidence for ongoing volcanism was observed by Venus Express in the form of four transient localized infrared hotspots within the rift zone Gannis Chasma near the shield volcano Maat Mons.

Three of the spots were observed These spots are thought to represent lava freshly released by volcanic eruptions.

The actual temperatures are not known because the size of the hotspots could not be measured but are likely to have been in the 800-1100 Kelvin range relative to a normal temperature of 740 Kelvin.

These are images of the Maat Mons region taken by the Magellan orbiter.

Using computer simulations,

They determined that the topography had changed during an 8-month interval and concluded that active volcanism was the cause.

There are almost 1,

000 impact craters on Venus,

Evenly distributed across its surface.

Craters show a range of states of degradation.

On the Moon,

Degradation is caused by subsequent impacts,

Whereas on Earth it is caused by wind and rain erosion.

On Venus,

About 85% of the craters are in pristine condition.

The number of craters,

Together with their well-preserved condition,

Increased from 1,

000 to 600 million years ago followed by a decay in volcanism.

Whereas Earth's crust is in continuous motion,

Venus is thought to be unable to sustain such a process.

Without plate tectonics to dissipate heat from its mantle,

Venus instead undergoes a cyclical process in which mantle temperatures rise until they reach a critical level Then,

Over a period of about 100 million years,

Subduction occurs on an enormous scale,

Completely recycling the crust.

Venusian craters range from 3 to 280 km in diameter.

No crater is smaller than 3 km because of the effect of the dense atmosphere on incoming objects.

Atmospheric and kinetic energy are slowed so much by the atmosphere that they do not create an impact crater.

Incoming projectiles less than 50 m in diameter will fragment and burn up in the atmosphere before reaching the ground.

Without data from reflection seismology or knowledge of its moment of inertia,

It is impossible to understand the structure and geochemistry of Venus.

The similarity in size and density between Venus and Earth suggests that they share a similar internal structure,

A core,

Mantle and crust.

Like that of Earth,

The Venusian core is most likely at least partially liquid when cooled out.

The slightly smaller size of Venus means pressures are 24% lower in its deep interior than Earth's.

The predicted values for the moment of inertia based on planetary models suggest a core radius of 2,

900 to 3,

450 km.

There is now an estimate of 3,

500 km from the moment of inertia based on the rate of axial precession,

Measured between 2006 and 2020.

The crust of Venus is estimated to be 40 km thick on average and at most 65 km thick.

The principal difference between the two planets is the lack of evidence for plate tectonics on Venus,

Possibly because its crust is too strong to subduct without water to make it less viscous.

This results in reduced heat loss from the planet,

Preventing it from cooling and providing a likely explanation for its lack of water to make major resurfacing events.

In 1967,

Venera 4 found Venus' magnetic field to be much weaker than that of Earth's.

This magnetic field is induced by an interaction between the ionosphere and the solar wind,

Rather than by an internal dynamo as in the Earth's core.

This causes convection to the atmosphere against solar and cosmic radiation.

The lack of an intrinsic magnetic field on Venus was surprising given that it's similar to Earth in size and was expected to contain a dynamo at its core.

A dynamo requires three things a conducting liquid,

Rotation,

And convection.

On Earth,

Although its rotation is often thought to be too slow,

Simulations show it is adequate to produce a dynamo.

This implies that the dynamo is missing because of a lack of convection in Venus' core.

On Earth,

Convection occurs in the liquid outer layer of the core which may have shut down plate tectonics and led to a reduced heat flux through the crust.

This insulating effect would cause the mantle temperature to increase thereby reducing the heat flux out of the core.

As a result,

No internal geodynamo is available to drive a magnetic field.

Instead,

The heat from the core is transferred to Venus.

One possibility is that Venus has no solid inner core or that its core is not cooling so that the entire liquid part of the core is at approximately the same temperature.

Another possibility is that its core has already been completely solidified.

The state of the core is highly dependent on the concentration of sulfur The possibility is that the absence of a large impact on Venus contra the Earth's moon-forming impact left the core of Venus stratified from the core's incremental formation and without the forces to initiate or sustain convection and thus a geodynamo.

The weak magnetosphere around Venus means that the solar wind interacts Here,

Ions of hydrogen and oxygen are being created by a disassociation of water molecules due to ultraviolet radiation.

The solar wind then supplies energy that gives some of these ions sufficient speed to escape Venus's gravity field.

This erosion process results in a steady loss of low-mass hydrogen,

Helium,

And oxygen ions whereas higher-mass molecules such as carbon dioxide are more likely to be retained.

Atmospheric erosion by the solar wind could have led to the loss of most of Venus's water during the first billion years after it formed.

However,

The planet may have retained a dynamo for its first 2-3 billion years so the water loss may have occurred more recently.

The erosion has increased the ratio of higher-mass deuterium to lower-mass hydrogen in the atmosphere 100 times compared to the rest of the solar system.

Unlike any other planet in the solar system the Venus atmosphere rotates much faster than the planet body with a period of 4 days versus 243 days.

This dense atmosphere composed of 96.

5% carbon dioxide 3.

5% nitrogen both exist as supercritical fluids at the planet's surface with a density of 6.

5% that of water and traces of other gases including sulfur dioxide.

The mass of its atmosphere is 92 times that of Earth's because the pressure at its surface is about 93 times that of Earth's a pressure equivalent to that at a depth of nearly 1 km under Earth's ocean surfaces.

The density at the surface is 65 kg per m³ 6.

5% that of water or 50 times as dense as Earth's atmosphere The CO2-rich atmosphere generates the strongest greenhouse effect in the solar system creating surface temperatures of at least 735 Kelvin.

This makes the Venusian surface hotter than Mercury's which has a minimum surface temperature of 53 Kelvin and maximum surface temperature of 3.

5 Kelvin and thus receives only around a quarter of Mercury's solar irradiance double that of Earth's.

Because of its runaway greenhouse effect Venus has been identified by scientists such as Carl Sagan as a warning and research object linked to climate change on Earth.

Therefore Venus has been called Venus's atmosphere is rich in primordial noble gases compared to that of Earth's.

This enrichment indicates an early divergence from Earth's in evolution.

An unusually large comet impact or accretion of a more massive primary atmosphere from the solar nebula have been proposed to explain the volcanic Argon 40 a proxy for mantle degassing suggesting an early shutdown of major magmatism.

Studies have suggested that billions of years ago the atmosphere of Venus may have been much more like the ones surrounding the early Earth and there may have been substantial quantities of liquid water The rising luminosity of the Sun and possibly large volcanic resurfacing caused the evaporation of the original water.

A runaway greenhouse effect was created once a critical level of greenhouse gases,

Including water was reached in the atmosphere.

Although the surface conditions on Venus are no longer hospitable like life that might have formed before this event,

There is speculation that life may exist in the upper cloud layers of Venus,

50 km above the surface where atmospheric conditions are the most Earth-like in the solar system with temperatures ranging between 303 and 353 Kelvin and the pressure and radiation being about the same as at Earth's surface due to carbon dioxide air.

More specifically,

Between heights of 48 and 59 km,

Temperature and radiation conditions are suitable for life.

At lower elevations water would evaporate and at higher elevation UV radiation would be too strong.

The putative detection of an absorption line of phosphine in Venus's atmosphere due to antibiotic production led to speculation in September 2020 that there could be extant life currently present in the atmosphere.

Later research attributed this spectroscopic signal that was interpreted as phosphine to sulfur dioxide or found that,

In fact,

There was no absorption line.

Thermal inertia and the transfer of heat mean that the surface temperature does not vary significantly between the hemispheres facing and not facing the Sun,

Despite Venus's slow rotation.

Winds at the surface are slow moving at a few km per hour but because of the high density of the atmosphere at the surface they exert a significant amount of force against obstructions and transport dust to the surface.

This alone would make it difficult for a human to walk through even without the heat,

Pressure and lack of oxygen.

Above the dense CO2 layer are thick clouds 45-70 km above the surface consisting mainly of sulfuric acid which is formed by a reaction catalyzed by UV radiation from sulfur dioxide and water,

Resulting in sulfuric acid hydrate.

Additionally,

The clouds contain approximately 1% ferric chloride.

Other possible constituents of the cloud particles are ferric sulfate,

Aluminum chloride and phosphoric anhydride.

Clouds at different levels have different compositions and particle size distributions.

These clouds reflect,

Like thick cloud cover on Earth,

About 70% of the sunlight that falls on them back into space.

And since they cover the whole planet they prevent visual observation of the surface.

The permanent cloud cover means that although Venus is closer than Earth to the Sun it receives less sunlight on the ground with only 10% of the received sunlight reaching the surface,

Resulting in average daytime levels of illumination at the surface of 14,

000 lux comparable to that on Earth's in the daytime with overcast clouds.

Strong 300 km per hour winds at the cloud tops go around Venus about every 4-5 Earth days.

Winds on Venus move at up to 60 times the speed of its rotation whereas Earth's fastest winds are only 10-20% rotation speed.

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