The Inner Planets

The Inner Planets

Mercury

• Small • Weak gravitational force • No atmosphere • Many craters

• Caloris Basin - one giant crater (1000 miles in diameter)

• Many cliffs and peaks evidence of tectonic activity

• Mean surface temp 442.5 K, ranges from 100 K to 700 K

http://solarsystem.nasa.gov/multimedia/videos/Keplers_Laws_fullscreen.mov

VenusEarth’s sister planet

• Covered with an opaque layer of highly reflective clouds of sulfuric acid

• Surface temperatures high enough to melt lead.

After the Moon, it is the brightest natural object in the night sky

• Orbits every 224.7 Earth days• Rotation is slow and retrograde, 243-day

period

• Time from one sunrise to the next is 117 Earth days

http://en.wikipedia.org/wiki/File:VenusAnimation.ogg

• Radius is 95% of Earth's, and the density similar to Earth's, 80%

• Liquid metal core similar to the Earth's

Atmosphere• Thick, high pressure (90 atm) • Density 50 times greater than on Earth! • Made of CO2, N, with sulfuric acid clouds• Strong greenhouse effect

Surface

• 450°C (850°F) hot!! everywhere, always, including night time

• Dry, dusty rocks, no water • May have had water in the past• Orange light, (atmosphere reflects mostly blue

light)

Phases of Venus

http://www.youtube.com/watch?v=ukPGqz4e_TY&feature=related

Mars

• most ``earthlike'' • 1/2 size of Earth • 24h 37m day • thin atmosphere of 95% CO2 • much colder than Earth -- 187o K to 244o K (-

123o F to -20o F ) • atmospheric pressure 0.7% of Earth's

(equivalent to 100,000 ft altitude on Earth)

• tilted 25o ---> seasons • dust storms originally thought to be bands of

vegetation ad irrigation canals built by Martians!

• http://www.disclose.tv/action/viewvideo/16067/Orson_Welles__War_Of_The_Worlds_Pt_2_7/

• clouds, sediment layers, canyons, landslides, sand dunes, enormous young volcanos as tall as 78,000 ft (flyby 1 and flyby 2)

• dry riverbeds (in older regions), evidence that liquid water once flowed

• no water in liquid state now, all water frozen in ice caps/permafrost

• The "Red Planet” iron oxide• Two moons, Phobos

Deimos

Surface features similar to Earth and the Moon

Atmosphere• Carbon dioxide 95.32%• Nitrogen 2.7% • Argon 1.6% • Oxygen 0.13%

Ice caps

First fly-by

• Mariner 3 (1965)

• http://www.hulu.com/watch/63307/cosmos-blues-for-a-red-planet