Venus has few craters young surface Dominated by volcanism Also has tec tonics

What are the major geological features of Venus? Venus has few craters - young surface Dominated by volcanism Also has tec ‣ ‣ ‣ ‣ ‣ - tonics but little or no erosion What are the major geological features of Mars? Differences in cratering across surface Giant shield volcanoes Evidence of tectonic activity What geological evidence tells us that water ‣ ‣ ‣ ‣ once flowed on Mars? Features that look like dry riverbeds Some craters appear to be eroded Rovers have found rocks that appear to have formed in water ‣ ‣ ‣ Which terrestrial planets have significant atmospheres? Venus, Earth, and Mars have significant atmospheres What features of Earth’s atmosphere are important for life? Atmospheric oxy ‣ ‣ ‣ - gen - from photosynthesis Radiation protection Moderate greenhouse effect Moderate atmospheric temperature and pressure make surface liquid water possible ‣ ‣ ‣ What is Venus like today? Venus has an extremely thick CO2 atmosphere Hottest planetary surface in the solar system How did Venus get so hot? Thick CO2 atmosphere leads to a ‣ ‣ ‣ ‣ huge greenhouse effect Why did Earth’s atmosphere end up so different? Temperatures just right for oceans of water Oceans keep most CO2 out of atmosphere ‣ ‣ ‣ ‣ What are jovian planets like? Thick hydrogen, helium atmospheres Layered interiors with very high pressure and cores made of rock, metals, and hydrogen compounds Very high pres ‣ ‣ ‣ - sure in Jupiter and Saturn can produce metallic hydrogen All have strong storms and winds What kinds of moons orbit jovian planets? Moons of many sizes Many major moons show ‣ ‣ ‣ ‣ signs of geological activity Tidal heating drives activity Titan is the only moon with a thick atmosphere ‣ ‣ ‣ What are Saturn’s rings like? Made up of countless individual ice particles Extremely thin with many gaps How do other jovian ring systems compare to Saturn’s? Much fainter ring ‣ ‣ ‣ ‣ systems with smaller, darker, less numerous particles Why do the jovian planets have rings? Ring particles are probably debris from moons ‣ ‣ What are asteroids like? Rocky leftovers from the era of planet formation Generally irregular in shape Some are “rubble piles” The majority are found in the asteroid belt, between the ‣ ‣