-Similar to Mercury because neither has a moon

                -But extremely similar to Earth; share the same mass, diameter, and average density

-But 30% closer to the sun—makes it inhabitable

-twice distance from sun as Mercury, so it is easier to see

Can see it high over the horizon after sunset “evening star” and before sunrise “morning star”

                -Brightest planet in sky (besides moon and sun)

                -Sometimes mistaken as UFO because when it is close to the Earth’s horizon, its bright light is refracted by Earth’s atmosphere, making it appear to change color and position

Pressure is 90 atm

                 Venus thick atmosphere 96% carbon dioxide, 4% other, mainly nitrogen (gases vented out from active volcanoes and other openings)

Levels of sulfur in Venus’ atmosphere varies (perhaps due to volcano activity)

Clouds are 20 km thick layer located 48 to 60 km above planet and appear yellow (due to sulfur dust in upper atmosphere; there is sulfur dioxide and hydrogen sulfide at lower elevations)

Above and below clouds is a 20 km thick haze

                Below the haze it is clear

Bright because it is surrounded by light-colored, highly reflective clouds

                Surface temperature is 750 K

No liquid oceans 

Pressure and temperature decrease smoothly with increasing altitude 

Why is Venus so much warmer than Mercury when it is farther from the sun?

                Carbon dioxide which is transparent to light, absorbs infared radiation that makes it through the atmosphere of Venus

                This warms the surface of the planet, which in turns releases infared radiation which cannot escape through the carbon-dioxide atmosphere (trapping heat inside)

                Thick atmosphere keeps both day and night side the same temperature

                High heats prevent liquid water from existing on Venus (too hot, would evaporate and leave planet)    

                Venus’ regoliath was covered by thin layer of lava that contracted when it cooled, creating rounded shapes

                Venus is very flat compared to Earth, more than 80% of it is volcanic plains and gently rolling hills (from the lava)

                Two continents on Venus

                Ishtar Terra in the northern hemisphere same size as Australia and dominated by high plateau of mountains (highest mountain is Maxwell Montes—11km above surface)

                Aphrodite Terra vast belt of highlands just south of the equator (half the size of Africa)

                1600 major volcanoes on Venus

                Fewer than 1000 impact craters

                Thick atmosphere and heat would keep most craters out

                (probably a period shortly after Venus formed where craters could get in)

Thought that entire surface of the planet melts due to the thickness of the crust that traps enormous amounts of heat within the core

                -believed that every 700 million years the crust melts and reforms (erasing crater evidence)

Has a retrograde rotation; Venus’ orbit around sun (counter clockwise) is opposite the direction of its rotation (clockwise)

                Means sun rises in the West

                Tilt is 177 degrees, close to being perpendicular to the orbit around the sun –hence no seasons

Mass, size and density (5340 kg/m3) similar to Earth

Composition and internal structure likely similar

No magnetic field

Due to slow rotation?

Pspin= 243 days

Large up-welling of mantle

Volcanoes in and around coronae

Unique to Venus

No long ridges or faults indicating plate tectonics

Many local deformations of surface, but not due to plate tectonics

Why No Plate Tectonics?

1.Thin lithosphere –could not support large scale tectonics so only local deformations created.

2.Thick lithosphere –