Week 6: Venus

Venus

Venus: has a thick atmosphere
- covered in clouds
- Diameter of Venus: 95% of Earth’s diameter
- Density: 5.2 g/cm³
- Mass: 80% the mass of the Earth
- Surface Gravity: 0.9 g (g=gravity)

until 1950, scientist thought Venus might be covered with rain forests
- possibly inhabited by photosynthetic, Alien, human-like forms
  - NOT TRUE
    - Venus is perhaps the most inhospitable place in the Solar System

Average distance from the Sun: 0.7 AU from the sun
- has the lowest eccentric (most circular) of all the planets orbits (0.007)

Venus’s greatest elongation angle: 48 degrees of separation
- bigger orbit than Mercury, so greater maximum elongation angle
Best seen before sunrise or after sunset
- sometimes called the “Evening Star” or “Morning Star”
- about 3 hours before/after, compared to Mercury’s 2 hours
Venus is the brightest planet

Conjunction: when objects are in the same direction (line up)
- Superior Conjunction: when the sun is between you and the other body
- Inferior Conjunction: when other body is between you and the sun
  - but planets that are further away from sun than earth will never be in inferior conjunction but can be in superior conjunction
    - ie: Mars will never be in inferior conjunction but can be in superior conjunction

Period of Rotation (length of Venusian Day): 243 days
- determined using the Doppler’s effect
- slowest rotation rate of any major planet
Rotation is Retrograde
- rotates backwards
axial tilt is confusing…
Period Revolution (Venusian Year): 225 days
- Venus’s day is longer than its Year
Venus has the highest “Albedo” in the Solar System (70%)
- Albedo: amount of light reflected from the body
- most reflective body in the Solar System

Venera 7: first probe to land on Venus and first probe to send back data from another planet
- daytime temperature: 900 degrees F
  - Hottest of all major planets!!
- Nighttime temperature: 850 degrees F
- Surface pressure: 90x greater than the Earth’s surface pressure
  - like being 3,000 ft underwater

Atmosphere contains:
- 95% Carbon dioxide (CO2)
- Sulfuric Acid Clouds
  - rains Sulfuric Acid

Venera 9 took the first photo of Venus
- this is also the first photo of another planet

venera 11 and 12 were sent but lens cap was not off and wasn’t able to take photos
Venera 13 took photos below:
Venera 14 took photos below:
Venera Landers: the only successful landings on Venus… ever

Radar mapped most of Venus’s surface
- no ancient water beds or shorelines
- no signs of water (erosions, etc)
Violent tectonic formations
- 85% of the surface is (cooled) volcanic lava floors
  - rest is mountains

has continents:
1. Ishtar Terra
  - has tallest mountain range on Venus’s surface (called Maxwell Montes)
    - only feature on Venus named after a male
2. Aphrodite Terra
  - half the size of Africa
has Mountains
has Craters (not many craters though)
- named after famous women
- why does Venus not have a lot of craters?
  - because it has an atmosphere and has erosion
  - volcanic activity has “resurfaced” the planet long ago
  - No small craters, only large ones
    - only big craters can get through Venus’s atmosphere
has Volcanos
- other features (such as volcanos) are named after various goddesses
- Corona: when magna builds up under surface
  - similar to a pimple under the skin

the thick CO2 atmosphere traps heat and creates a “Greenhouse effect”
- The Greenhouse effect: the process by which an atmosphere warms a planet
  - mars, Venus, and other celestial bodies with atmospheres (such as Titan) have greenhouse effects
  - without the greenhouse effect, life on Earth could not exist
Venus has a “Runway” greenhouse effect
- long time ago, Venus had an Ocean
  - Venus began to warm up from the sun getting hotter
    - Water from Ocean evaporated
      - water vapor enters the atmosphere and traps CO2
        CO2 in the atmosphere enchances the greenhouse efffect, trapping more heat
        more heat = more water evaporates and more CO2 trapping the heat
        cycle continues = Runway greenhouse effect