27.3 and 27.4 The Planets

The Inner Planets & The Outer Planets

Sections 27.3 & 27.4

Inner Planets· 4 closest to the sun

Mercury, Venus, Earth and Mars· called terrestrial planets because they are similar to Earth· mostly solid rock with metallic cores· covered in craters

bowl-shaped depression where collisions have occurred

Mercury

Venus EarthMars

Mercury· position in relation to sun - closest· orbital rotation - 88 days (very quick)· rotation on axis - 59 days· surface - heavily cratered and long line of cliffs· temp - 427 C to -173 C (due to slow rotation and no atmosphere)· atmosphere - none

Venus - "Evening or Morning Star"· position in relation to sun - 2nd from sun· orbital rotation - 225 days· rotation on axis - 243 days (very slow)· surface -

volcanoes, lava plains, mountains, sand dunes somewhat cratered

· temp - average 464 C (hottest planet)· atmosphere -

atmospheric pressure 90 time Earth's 96% carbon dioxide sulfur dioxide droplets form clouds around Venus

that reflects sun

Earth - "The Water Planet"· position from the sun - 3rd from sun· orbital rotation - 365 1/4 days· rotation on axis - 1 day· surface -

plate tectonics, weathering/erosion continuously change the surface

only planet with liquid water on surface· temp - 57 C to -101 C (temperature moderated by Greenhouse effect)· atmosphere - 78% nitrogen, 21% oxygen, 1% other

Mars - The Red Planet· position in relation to sun - 4th from sun· orbital rotation - 687 days· rotation on axis - 24 hours, 37 minutes· surface -

massive volcanoes, deep canyons

evidence of liquid water on surface in the past

· temp - 20 C to -130 C· atmosphere - low atmospheric pressure

27.3 and 27.4 The Planets

Outer Planets· separated from inner planets by an asteroid belt (ring of debris)· called gas giants because they have a thick, massive atmosphere made mostly of gas· larger and more massive than inner planets· cloud layer prevents scientist from directly observing more than the topmost part of the atmosphere

Jupiter - largest planet· moons/rings - at least 60 moons and several thin rings· position in relation to sun - 5th from sun· orbital rotation - about 12 years· rotation on axis - 9 hours, 50 minutes (fastest)· temp - average -160 C· composition - gas giant

92% hydrogen and helium storms common winds up to 540 km/hr

Saturn - least dense planet· moons/rings - 53, most complex and extensive system of rings· position in relation to sun - 6th from sun· orbital rotation - about 29.5 years· rotation on axis - 10 hours, 30 minutes· temp - average -157 C· composition - gas giant

almost entirely hydrogen bands of colored clouds bulges at equator

Uranus - unusual orientation· moons/rings - 24 moons and 11 thin rings· position in relation to sun - 7th from sun· orbital rotation - 84 years· rotation on axis - about 17 hours· temp - average -214 C (might be higher under its cloud cover)· composition - gas giant

mainly hydrogen and helium lots of methane gives it a blue/green color

Neptune· moons/rings - 13 moons and 9 rings· position in relation to sun - 8th from sun· orbital rotation - 164 years· rotation on axis - 16 hours· temp - average -225 C· composition - gas giant

mainly hydrogen, helium, and methane active weather system strongest winds about 1000 km/hr