Astronomy Space Planet

Venus ♀

• 0.72 AU from the Sun
• Goes through phases like the Moon
  • Discovered by Galileo
  • Helped prove that Venus didn't orbit Earth
• Orbits the sun in 225 days
• Rotational period: 243 days
  • Measured by bouncing radar signals off the planet
  • Day is longer than a year!
• Spins east --> west
  • Backwards compared to most planets in the Solar System
  • Possibly caused by an early collision during the formation of the Solar System
• Gravity is similar to gravity on Earth

Atmosphere

• 96% carbon dioxide
• Covered by clouds
  • Reflect ~70% of the sunlight
  • Makes it harder to study from a distance
• Very dry
  • Absence of water is one important way it differs from Earth
• Huge troposphere
  • Region of convection
  • Extends up to at least 50 km
• About 90x the atmospheric pressure of Earth
  • Like being 1 km underwater

Surface

• Surface is hot --> 730K (over 850˚ F)
  • Thanks to the runaway greenhouse effect
    • Worse than on the Earth
    • Produces more greenhouse gases
    • Since Venus has so much carbon dioxide the effect is almost a million times stronger than on Earth
  • Melting crust
• 75% of the surface consists of lowland lava plains
• Has persistent geological activity
  • Surface age is between 300 and 600 million years
• No plate tectonics
  • Weak mantle convection