The 8 Planets – Part 2: Venus



An inferno fireball on the inside, a smooth yellow marble on the outside. Venus, the two-faced planet known as “heaven and hell.” Beautiful yet dangerous, Venus is rightfully named after the Roman goddess of love and beauty. In modern culture, people associate Venus with beauty products… and Venus Williams, the world champion tennis player.

Shrouded by its thick sulfuric cloud atmosphere, Venus is the second planet from the Sun and the hottest planet on average in the solar system. Also known as the Morning Star or Evening Star, Venus reflects sun light strongly, with a high albedo. Because Venus’ size is similar to Earth’s, Venus is sometimes to referred to as “Earth’s twin” or “Earth’s sister.” Other than size, however, Venus and Earth have nothing in common. Venus’ atmosphere rains sulfuric acid on the dry dessert-like surface! Its thick atmosphere (90 times thicker than Earth’s) composed of mainly CO2 traps carbon dioxide (greenhouse effect) and maintains a searing temperature on Venus. Venus may have harbored water once, but rising temperatures evaporated all liquid water, leaving a volcanically active surface.  Mapped in 1990-1991 by Project Magellan, Venus’ surface comprises of 80% smooth, volcanic plains (70% plains with wrinkled ridges and 10% smooth plains) and 20% two highland “continents” Aphrodite Terra and Ishtar Terra. Venus has little impact craters but various volcanic features such as “novae” (star-like fracture systems) and “arachnoids” (spider-web-like fractures). Scientists know little about Venus’ interior without seismic data, but Venus’ size and density suggest an interior similar to Earth’s. Scientists have attempted to build probes to land on Venus’ surface, but all attempts failed (most only enter Venus’ atmosphere then burn up and crash). Venus’ clouds reflect and scatter 90% of sunlight, so scientists can only map its surface with radar. In fact, Venus’ atmosphere has an ozone layer and its clouds can produce lightning! Unlike any other planet, Venus spins from east to west, in a retrograde motion. Because Venus spins backward, its rotational period is longer than its orbital period; a day on Venus is longer than a year! Unlike Earth, Venus has a negligible magnetic field, unable to divert most solar wind. Like Mercury, Venus undergoes phases as seen from Earth. When Venus is in a crescent phase observers can actually see a mysterious ashen light. In the 17th century, Galileo proved the heliocentric theory with observations of Venus’ phases. Though Venus has no moons, scientists believe the planet had at least one that crashed into its surface. 10 million years after the collision, another impact changed Venus’ spin. Another possibility is that strong solar tides can disturb large satellites. Recently, the Transit of Venus occurred in June, when the planet crossed over the Sun.

MISSIONS: Venera, Sputnik, Mariner, Cosmos, Vega, Pioneer Venus, Magellan, Cassini, MESSENGER, Venus Express

*Many of these missions (Sputnik, Mariner) are series with only some successful and some only fly-bys; Venera is exclusive for Venus


  • Order in Solar System: #2
  • Number of Moons: 0
  • Orbital Period: 225 days
  • Rotational Period: 243 days
  • Mass: 4.8685 x 10^24 kg (0.815 Earths)
  • Volume: 9.28 x 10^11 km³ (0.866 Earths)
  • Radius: 6,052 km (0.9499 Earths)
  • Surface Area: 4.60 x 10^8 km² (0.902 Earths)
  • Density: 5.243 g/cm
  • Surface Pressure: 9.3 MPa
  • Eccentricity of Orbit: 0.2
  • Surface Temperature (Average): 735 K
  • Escape Velocity: 10.36 km/s
  • Apparent Magnitude: -4.9 (crescent) to -3.8 (full)

6 thoughts on “The 8 Planets – Part 2: Venus

  1. It’s fascinating, Tina. Galileo was (still is) a great physicist, Mathematician, and astronomer. His contributions to astronomy were enormous and did it by himself. It’s sobering to think of how he had to deal with the tremendous pressure from Vatican while working on his development…
    Thank you so much for another wonderful post, Tina

    • Amy,
      Great to see you 🙂 I agree. What Galileo accomplished is unparallelled. Despite the Vatican, Galileo revolutionized astronomy and continued to contribute even when the church placed him under house arrest. Galileo is one my personal favorite scientists!

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