Venus Planet

Physical Properties of Terrestrial Planets

  • Similar densities & sizes, but variations in:

    • Rotation periods

    • Surface temperatures

    • Atmospheric pressures

Terrestrial Planets Comparison

  • Mass Compared to Earth

    • Mercury: 3.3x10^23 kg (0.055 Earth)

    • Venus: 4.9x10^24 kg (0.82 Earth)

    • Earth: 6.0x10^24 kg (1.0 Earth)

    • Mars: 6.4x10^23 kg (0.11 Earth)

  • Size Compared to Earth

    • Mercury: 2400 km (0.38 Earth)

    • Venus: 6100 km (0.95 Earth)

    • Earth: 6400 km (1.0 Earth)

    • Mars: 3400 km (0.53 Earth)

  • Average Density (kg/m3)

    • Mercury: 5400

    • Venus: 5300

    • Earth: 5500

    • Mars: 3900

  • Atmospheric Pressure (Earth=1)

    • Mercury: 100-700

    • Venus: 730

    • Earth: 290

    • Mars: 0.007

Venus – “Earth’s Twin”

  • Closest planet to Earth at ~27 million miles

  • Shares similarities with Earth:

    • Diameter: 12102 km vs. 12756 km

    • Mass: 82% that of Earth

    • Density: 5.3 g/cm3

    • Gravitational field strength: 0.91 G

Venus’s Rotation

  • Surface features obscured by thick cloud cover

  • Rotation period of 243 days

  • Retrograde rotation (clockwise), opposite to orbit (counterclockwise)

    • Likely caused by a historical collision with another planet

Venus’s Atmosphere

  • Extremely hot: Surface temperatures at 730 K

  • Very thick and dense, with pressure 90 times that of Earth's sea level

  • Composition:

    • Carbon Dioxide: 96.5%

    • Nitrogen: 3.5%

  • Very dry atmosphere

  • Clouds consist of sulfuric acid

Atmospheric Features

  • UV & IR imagery:

    • 50-70 km: fast-moving clouds at 400 km/h

    • 30-50 km: haze

    • Clear below 30 km

  • Polar vortex discovered over the south pole

Venus’s Atmosphere Evolution

  • Initially similar to Earth’s atmosphere

  • Factors influencing current conditions:

    • Closer proximity to the Sun

    • Higher natural evaporation rates

    • Less CO2 retention in warmer waters and rocks

    • Enhanced greenhouse effect leading to high CO2 levels

Greenhouse Effect on Earth and Venus

  • Basic Process:

    1. Sunlight enters atmosphere

    2. Heats the ground

    3. Ground emits IR radiation

    4. Carbon dioxide traps the outgoing IR radiation

  • Venus Specifics:

    • 99% of outgoing infrared radiation trapped

    • Results in elevated surface temperature of 730 K

Surface of Venus

  • Mapped using radar imaging

  • Surface elevation features:

    • White areas indicate high elevations, blue represents lower areas

  • Characteristics:

    • Smooth surface with rolling plains, highlands, and lowlands

    • Continental features cover 8% of the surface

    • Includes Ishtar Terra and Aphrodite Terra with mountains comparable to Earth's height

Volcanoes on Venus

  • Major surface features that drastically alter the landscape every few hundred million years

  • Features include:

    • Lava domes: up to 25 km across

    • Common shield volcanoes, akin to those in Hawaii

    • Hot spots where lava emerges through the crust

Shield Volcanoes on Venus

  • Caldera: crater formed when lava withdraws, leading to surface collapse

  • Example: Gula Mons as a large shield volcano

Volcanic Structures on Venus

  • Coronae:

    • Largest volcanic structures

    • Circular formations caused by upwelling in the mantle

    • Surrounded by volcanoes and cracks

    • Example: Aine as one coronae

    • Evidence of volcanic activity includes sulfur dioxide observations above clouds and lightning phenomena

Impact Craters

  • Visible impact craters with varied shapes:

    • Some irregular; others are regular shapes

  • Largest impact crater: Mead

Venus’ Interior

  • Lacks a magnetic field

  • Composition resembles that of Earth:

    • Structure likely consists of crust, mantle, and core

    • Possesses a liquid iron core

  • Slow rotation contributes to the absence of a magnetic field

Venus’ Geology

  • Surface suggests it resembles Earth’s long-ago geology

  • Characteristics include:

    • Thin crust with limited tectonic activity

    • High surface temperature affects geological evolution

    • Slowed cooling rates; soft crust hampers plate motion

    • Increased volcanism keeps energy loss to a minimum, impacting geological dynamics.