Craters on Mars Many craters Closer to asteroid belt No water erosion Older surface Cratering is not uniform More in southern hemisphere

Southern Cratered Terrain Comparable to Lunar Highlands More worn down

Erosion of Craters

Regions on Mars Q. 39: Age of Mars Regions Southern Hemisphere Heavily Cratered Northern Hemisphere Medium Craters Tharsis Region Fewest Craters Q. 39: Age of Mars Regions

The Tharsis Region Elevated region Volcanic outflows Volcanoes nearby Probably extinct So large they can be seen easily from space

Olympus Mons Giant Volcano Largest Mountain in Solar System Top sticks out of atmosphere

Olympus Mons Three times taller than Mt. Everest Bigger than North Carolina

Olympus Mons Q. 40: Mars’s Volcanoes

Mars Volcanoes Smaller planets cool more quickly Mars probably has no active volcanoes now But it did within past billion years or so

Mars Composition Mars has virtually no global magnetic field No protection for life from cosmic rays Internal Structure: Crust, thicker than Earth (?) Mantle, most of the volume Solid core near the center

Valles Marineris Largest Valley in the Solar System As big across as USA Crack caused by weight of Tharsis Bulge

Valles Marineris

Candor Chasma

The Polar Caps on Mars Carbon dioxide (dry ice) layer on top Water ice underneath

The Northern Polar Cap Size of cap changes seasonally Carbon dioxide evaporating and refreezing Causes large change in atmospheric pressure (50%)

Global Dust Storms Atmosphere flow causes huge dust storms Can envelope entire planet

Clouds on Mars

Dust Devils on Mars Mini-tornadoes Leave tracks across surface

Sand Dunes on Mars

Water on Mars Current pressure slightly too low for liquid water to form Mars Phoenix confirmed there is permafrost near poles We also have seen frost on the ground Was there liquid water on the surface in the past?

Past Evidence of Water

Craters and Evidence for Water Some craters look like they were made in mud Teardrop shaped islands look like terrestrial islands in rivers

Dried up Lakes

Water-based Minerals “Blueberries” are hematite Mineral normally only forms in water Strong evidence of past water

Civilization on Mars! Cydonia Region The Face Natural Features

Life on Mars! Mars has water – could it have life? A meteorite found in 1984 is one of several known to have come from Mars This meteorite contained what some thought were fossilized bacteria Scientists divided

Life on Mars? The conditions on Mars are rather different from Earth Mostly colder temperatures No oxygen, low air pressure No liquid water No large form of life on Earth survives these conditions But some bacteria on Earth live in similar conditions! What would life on Mars look like? Bacterial, too small to see without a microscope Probably live well below the surface (cosmic rays) Water-based

Mars Moons Two small moons Phobos Deimos Probably captured asteroids Phobos the size of Winston-Salem

Jupiter and Saturn Images Spectacular ring system Complex striped appearance

Jupiter and Saturn – How we know Pioneer 11 and 12 (flyby ’73-’74) Voyager 1 and 2 (flyby ’79) Galileo (orbiter ’95–’03) Galileo probe (’95) Cassini (flyby, ’00) New Horizons (flyby, ’07) Juno Mission (orbiter since ’16) Telescopes (ongoing) Saturn: Pioneer 11 (flyby ’79) Voyager 1 and 2 (flyby ’80 – ’81) Cassini (orbiter ’04–’17) Huygens (probe ’05) Telescopes (ongoing)

Past Spacecraft at Jupiter Galileo Galileo Probe Galileo spacecraft orbited Jupiter Galileo probe parachuted into Jupiter’s atmosphere New Horizons on way to Pluto New Horizons

Current and Future Missions to Jupiter Juno Juno mission in orbit since 2016 Jupiter Icy Moons Explorer launches in 2022 Europa Clipper in 2025 JUICE Europa Clipper

Spacecraft at Saturn Voyager 1 and 2 Cassini Huygens on Titan Voyagers flew past Cassini in orbit Huygens probe went to surface of Titan Huygens on Titan

Jupiter and Saturn – Size and Mass Size – 11  Earth (Jupiter) and 9  Earth (Saturn) Mass – 318  Earth (Jupiter) and 95  Earth (Saturn) Jupiter significantly less dense than Earth Saturn much less dense than Earth Orbits: 5.2 AU, 9.6 AU 12 years, 29 years