23.2 The Terrestrial Planets

Mercury: The Innermost Planet 2 nd smallest planet Absorbs most of the sunlight that hits it & reflects only 6 % of sunlight back into space Cratered highlands Smooth terrains that resemble maria Dense planet (large iron core) Long scarps (deep slopes) that cut across the plains & craters (from crustal changes as the planet cooled & shrank) Mercury has the greatest temperature extremes of any planet

Venus: The Veiled Planet Named for the goddess of love & beauty Orbits the sun in perfect circle every 255 Earth days Similar to Earth in size, density, mass, & location Covered in thick dark clouds (visible light can’t penetrate) Basaltic volcanism & tectonic activity 80% covered by volcanic flow 8% of surface consists of highlands Surface temp. reaches 475 degrees Celsius Atmosphere is 97% carbon dioxide

Mars: The Red Planet Appears as a reddish ball when looked at with a telescope Dark regions that change intensity during the Martian year White polar caps are very prominent with telescope Martian Atmosphere has 1% the density of Earth’s Made up of mostly CO2 & Water vapor Mariner 9 first spacecraft to orbit another planet (1971) Volcanoes & Canyons

Continued… Some areas of Mars exhibit drainage patterns similar to those created by streams on Earth Groundwater recently migrated to the surface Created gullies Many believe that they were created by the collapse of surface material caused by the slow melting of subsurface ice Many believe that Mars didn’t once have a water cycle like we do on Earth

REVIEW REVIEW REVIEW MARS The Red Planet

REVIEW REVIEW REVIEW Which inner planet is the smallest? How does Venus compare with Earth? What surface features does Mars have that are also common on Earth?