Chapter 24: Section 2Chapter 24: Section 2

The Inner PlanetsThe Inner Planets

II. The Inner PlanetsII. The Inner Planets

A. Called A. Called Terrestrial PlanetsTerrestrial Planets1. First four planets: 1. First four planets: MercuryMercury, , VenusVenus, , EarthEarth, , MarsMars2. All have a solid crust surface2. All have a solid crust surface3. Most have an atmosphere of some kind 3. Most have an atmosphere of some kind 4. Most have at least one moon4. Most have at least one moon

Pgs. 646 - 650

B. MercuryB. Mercury1.1. Closest planet to the SunClosest planet to the Sun

a.a. Revolution time:Revolution time: 88 days88 daysb.b. Rotation time:Rotation time: 59 days59 days

2.2. Third smallest planetThird smallest planet3.3. Probed by Probed by Mariner 10 (1974-1975)Mariner 10 (1974-1975)

a.a. Imaged 45% of surfaceImaged 45% of surfaceb.b. Surface crater riddled (similar to our Moon)Surface crater riddled (similar to our Moon)c.c. Has large cliff lined valleysHas large cliff lined valleysd.d. Has a weak magnetic field (indicates iron core)Has a weak magnetic field (indicates iron core)

B. MercuryB. Mercury3.3. Probed by Probed by Mariner 10 (1974-1975)Mariner 10 (1974-1975)

e.e. Very thin atmosphere: Very thin atmosphere: 1. Hydrogen, Helium, Sodium & Potassium1. Hydrogen, Helium, Sodium & Potassium

f.f. Surface Temperature:Surface Temperature:1. Daytime: 842 1. Daytime: 842 ooFF2. Night: -274 2. Night: -274 ooFF

C. VenusC. Venus1.1. Second planet from the sunSecond planet from the sun

a.a. Revolution: 255 daysRevolution: 255 daysb.b. Rotation: Retrograde = spins backwardsRotation: Retrograde = spins backwardsc.c. Probed by Venera (Russian) in 1970Probed by Venera (Russian) in 1970d.d. Probed by Magellan (US) in 1990 to 1994Probed by Magellan (US) in 1990 to 1994

2.2. ““Earth’s Twin Sister”Earth’s Twin Sister”a.a. Size, Mass, Gravity similar to EarthSize, Mass, Gravity similar to Earth

C.C. VenusVenus33. Atmosphere: Thick & toxic. Atmosphere: Thick & toxic

a.a. Air Pressure = 90 times that of EarthAir Pressure = 90 times that of Earthb.b. Mostly carbon dioxideMostly carbon dioxidec.c. Clouds: Rain sulfuric acidClouds: Rain sulfuric acidd.d. Only allow 2% of sunlight through to surfaceOnly allow 2% of sunlight through to surface

1.1. Solar energy trapped = extreme Greenhouse EffectSolar energy trapped = extreme Greenhouse Effect

Chapter 23: Section 2Chapter 23: Section 2

C. Venus (continued)C. Venus (continued)4.4. Surface temperature = 878 Surface temperature = 878 ooFF

a.a. Surface covered by craters, fault lines, & VolcanoesSurface covered by craters, fault lines, & Volcanoesb.b. Winds = 300 km / hr.Winds = 300 km / hr.

Earth:Earth:D. EarthD. Earth

1.1. ““Third Rock from the Sun”Third Rock from the Sun”2.2. Average distance from the sun = 93,000,000 milesAverage distance from the sun = 93,000,000 miles3.3. Only planet water exists as 3 states of matterOnly planet water exists as 3 states of matter

a.a. Solid, Liquid, & GasSolid, Liquid, & Gas4.4. Atmosphere protects the planetAtmosphere protects the planet

a.a. From meteor strikes (most burn up)From meteor strikes (most burn up)b.b. Intense Solar Radiation (UV, X-Rays, Gamma Rays, etc.)Intense Solar Radiation (UV, X-Rays, Gamma Rays, etc.)

Ch 23: Section 2Ch 23: Section 2E. MarsE. Mars

1.1. Fourth Planet from the SunFourth Planet from the Sun2.2. ““The Red PlanetThe Red Planet””3.3. Surface mainly iron oxide dust Surface mainly iron oxide dust

(Rust)(Rust)4.4. Revolution time: 687 daysRevolution time: 687 days5.5. Has polar ice capsHas polar ice caps

a. Northern: frozen Water (Ha. Northern: frozen Water (H22O)O)b.b. Southern: frozen Carbon Southern: frozen Carbon

Dioxide (CODioxide (CO22))

F. F. Discoveries on MarsDiscoveries on Mars1.1. Mariner 9Mariner 9 (1971–1972) (1971–1972)

a.a. Discovered dried riverbedsDiscovered dried riverbedsb.b. Olympus Mons:Olympus Mons: Largest know volcano in the Solar Largest know volcano in the Solar

SystemSystemc.c. Rift Zones: Deep crustal tearsRift Zones: Deep crustal tears

2.2. Viking 1 & 2 (1976)Viking 1 & 2 (1976)a.a. Each consisted of Orbiter & LanderEach consisted of Orbiter & Landerb.b. Photographed entire Martian surface (OrbitersPhotographed entire Martian surface (Orbiters))

F. Discoveries on Mars (continued)F. Discoveries on Mars (continued)3.3. Mars’s AtmosphereMars’s Atmosphere

a.a. Studied meteorological, chemical, & biological aspects Studied meteorological, chemical, & biological aspects 1.1. Discovered barren, rocky, windswept surfaceDiscovered barren, rocky, windswept surface2.2. Atmosphere: very thin; Carbon Dioxide, Nitrogen & Atmosphere: very thin; Carbon Dioxide, Nitrogen &

ArgonArgon3.3. Surface Temperatures: 95Surface Temperatures: 95ooF (day) to -274 F (day) to -274 ooF (night) F (night) 4.4. Temperature changes create intense winds & dust Temperature changes create intense winds & dust

stormsstorms5.5. NO evidence of life (past or present)NO evidence of life (past or present)

G.G. Martian SeasonsMartian Seasons1. Mars’s axis of rotation is tilted 25 degrees, which is close

to Earth’s tilt of 23.5 degrees. 2. Because of this Mars goes through seasons as it orbits the

Sun. a. As one ice cap grows smaller, the other grows larger.

3. The color of the ice caps and other areas of Mars also changes with the seasons.

a. This is caused by the movement of dust and sand during dust storms.

H.H. Martian MoonsMartian Moons1.1. Mars has small, crater riddled moonsMars has small, crater riddled moons

a.a. Phobos:Phobos: 25 km in diameter 25 km in diameter1.1. Slowly spiraling toward MarsSlowly spiraling toward Mars2.2. Expected impact of surface in 50 million yearsExpected impact of surface in 50 million years

b.b. Deimos:Deimos: 13 km in diameter 13 km in diameter2.2. Both are irregularly shapedBoth are irregularly shaped3.3. Both orbit Mars several times a dayBoth orbit Mars several times a day

Mission to Mars ?Mission to Mars ? How should Mars be explored?How should Mars be explored?

– Travel time to Mars is a considerationTravel time to Mars is a consideration Orbits at their closest = 1.5 years travel timeOrbits at their closest = 1.5 years travel time Orbits at their farthest = over 5 years travel timeOrbits at their farthest = over 5 years travel time

– Length of travel time invites great risks to humansLength of travel time invites great risks to humans Should humans explore Mars?Should humans explore Mars?

– Humans do more meticulous & detailed work than probesHumans do more meticulous & detailed work than probes– Zero gravity travel weakens muscles & bonesZero gravity travel weakens muscles & bones– Body fluids move upward (increase kidney function)Body fluids move upward (increase kidney function)– Radiation exposure drastically increasedRadiation exposure drastically increased

Should robots explore Mars?Should robots explore Mars?– Robots aren’t affected by 0 G’s; travel time not a factorRobots aren’t affected by 0 G’s; travel time not a factor– Robots using videotronics can be controlled from EarthRobots using videotronics can be controlled from Earth

Signals can have up to 20 min. delaySignals can have up to 20 min. delay Robots cannot improvise & adapt to changing situations Robots cannot improvise & adapt to changing situations