- concretions of hematite (a mineral that forms in water)- microscopic imager found rippled bedding patterns in rock which are characteristic of rock sediment forming in flowing water-Mars’ south pole-Probe: the Mars Express (ESA and NASA)-News posted: March 2007-Instrument: Mars advanced radar for subsurface and ionospheric sounding-Results:- extensive frozen water at south pole- the polar region contains enough water ice that if melted it would cover the entire planet in liquid 36 feet deep- radar sees through the icy layer to the lower boundary- polar water ice deposit is below frozen carbon dioxide cap- methane in atmosphere-Volcanoes on Mars may still be active-Some meteorites from Mars are only 180 million years old (young) 3. Venus -Has a thick cloudy atmosphere – you cannot visually see the surface -We must image the surface using radar -Smooth plains with few mountain ranges -Few craters -Many volcanoes and domes of lava (corona)
-Atmosphere (pressure) 90 times thicker than Earth’s -Clouds of sulfuric acid -860 o F+ surface -Volcanism & tectonics on Venus - the corona is a tectonic feature - rising plume in mantle pushes crust up - cause circular stretch marks - plume forces magma to the surface - volcanoes are found nearby - impact craters are evenly spread over Venusian surface - implies that the planet’s entire surface is the same age - crater counting suggests an age of 1 billion years old - volcanism “paved over” the surface 1 billion years ago - 2 types of volcanism are observed: shield volcanoes & stratovolcanoes -Lack of erosion on Venus - no erosion features have been found on Venus so far - this means no wind, rain, or ice on the surface - such a lack of weather can be explained: - the surface of Venus is very hot (430 o C)…too hot for liquid or ice to exist - Venus rotates very slowly (P=243 days), so no wind is generated 4. Earth -Most active geology of terrestrial planets -Volcanoes & tectonics - ongoing plate tectonics (only on Earth) -Moderate atmosphere - N 2 , 0 2 , H 2 O -H 2 O exists in liquid state - rampant erosion - few craters -Life V. How do they compare? • Volcanoes on Mars may still be active • Some meteorites from Mars are only 180 million years old • Comparing the geology of the terrestrials -Things that play a role: - size: active or inactive geology? - distance from the sun: atmosphere? Liquid water? Frozen? - rotation: powers winds CHAPTER 10: PLANETARY ATMOSPHERES I. How atmospheres affect planets * Average surface temperatures Day Night Change Mercury 797 o F -283 o F 1080 o F Moon 257 o F -283 o F 540 o F
Mars 68 o F -220 o F 288 o F Venus 860 o F all the time!